Silurian and Devonian in Vietnam—Stratigraphy and facies

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Journal of Geodynamics

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ilurian and Devonian in Vietnam—Stratigraphy and facies

ong-Dzuy Thanha,∗, Ta Hoa Phuonga, Janvier Philippeb, Nguyen Huu Hungc,guyen Thi Thu Cuca, Nguyen Thuy Duonga

Laboratory of Historical Geology, Vietnam National University, 334 Nguyen Trai Str., Thanh Xuan District, Hanoi, Viet NamUMR7207 du CNRS, Muséum National d’Histoire Naturelle, 8 rue Buffon, 75005 Paris, FranceInstitute of Geosciences and Mineral Resources, Thanh Xuan District, Hanoi, Viet Nam

r t i c l e i n f o

rticle history:eceived 6 August 2010ccepted 10 October 2011vailable online xxx

eywords:ilurianevoniantratigraphyaciesiet Nam

a b s t r a c t

Silurian and Devonian deposits in Viet Nam are present in several zones and regions, including QuangNinh, East Bac Bo, and West Bac Bo Zones of the Bac Bo Region, the Dien Bien-Nghe An and Binh Tri ThienZones of the Viet-Lao Region, and the South Trung Bo, and Western Nam Bo Zones of the South Viet NamRegion (Fig. 1). The main lithological features and faunal composition of the Silurian and Devonian Unitsin all these zones are briefly described.

The Silurian consists of deep-water deposits of the upper parts of the Co To and Tan Mai Formations inthe Quang Ninh Zone, the upper parts of the Phu Ngu Formation in the East Bac Bo Zone and the upperparts of the Long Dai and Song Ca Formations in the Viet-Lao Region. Shallow water facies Silurian unitscontaining benthic faunas are more widely distributed, including the upper part of the Sinh Vinh and BoHieng Formations in the West Bac Bo Zone, the Kien An Formation in the Quang Ninh Zone, and, in theViet-Lao Region, the Dai Giang Formation and the upper part of the Tay Trang Formation.

No Lower and Middle Devonian deposits indicate deep water facies, but they are characterized bydifferent shallow water facies. Continental to near shore, deltaic facies characterize the Lower DevonianSong Cau Group in the East Bac Bo Zone, the Van Canh Formation in the Quang Ninh Zone, and the A ChocFormation in the Binh Tri Thien Zone. Similar facies also occur in the Givetian Do Son Formation of theQuang Ninh Zone, and the Tan Lap Formation in the East Bac Bo Zone, and consist of coarse terrigenousdeposits—cross-bedded conglomerates, sandstone, etc. Most Devonian units are characterized by shallowmarine shelf facies. Carbonate and terrigenous-carbonate facies dominate, and terrigenous facies occurin the Lower and Middle Devonian sections in some areas only.

The deep-water-like facies is characteriztic for some Upper Devonian formations in the Bac Bo (BangCa and Toc Tat Formations) and Viet-Lao Regions (Thien Nhan and Xom Nha Formations). These for-mations contain cherty shale or siliceous limestone, and fossils consist of conodonts, but there are alsobrachiopods and other benthos. They were possibly deposited in a deep water environment on the slopeof the continental shelf.

Most Devonian units distributed in the North and the Central Viet Nam consist of self shallow watersediments, and apparently they were deposited in a passive marginal marine environment. The coarseclastic continental or subcontinental deposits are distributed only in some areas of the East Bac Bo andof the Quang Ninh zones of the Bac Bo Region, and in the south of the Binh Tri Thien Zone. This situationsuggests the influence of the Caledonian movement at the end of the Silurian period that called the

uth C
Guangxi movement in So
. Introduction

The Silurian and Devonian deposits of Viet Nam were first

Please cite this article in press as: Tong-Dzuy T., et al., Silurian and

doi:10.1016/j.jog.2011.10.001

iscovered and described by French geologists of the Geologicalurvey of Indochina (Saurin, 1956). Later, they have been system-tically studied by Dovjikov et al. (1965), Tong-Dzuy Thanh (1993),

∗ Corresponding author. Tel.: +84 1696456546; fax: +84 438583061.E-mail address: [email protected] (Tong-Dzuy T.).

264-3707/$ – see front matter © 2011 Elsevier Ltd. All rights reserved.oi:10.1016/j.jog.2011.10.001

hina.© 2011 Elsevier Ltd. All rights reserved.

Tong-Dzuy Thanh et al. (1988), Vu Khuc and Bui Phu My (1990),and Tong-Dzuy Thanh and Vu Khuc (2006). Major contributions inthe description of Silurian and Devonian units have been made bygeologists from the Geological Mapping Division, during the lastdecades of the 20th century (1:200,000 geological maps). Strati-graphic units have been well established and their correlations are

Devonian in Vietnam—Stratigraphy and facies. J. Geodyn. (2011),

based on abundant faunas. Their study shows that Silurian andDevonian deposits are widespread in the North and the Centralparts of the country, whereas in the South there are only terrige-nous deposits of suspected Devonian age. New data on the Silurian

dx.doi.org/10.1016/j.jog.2011.10.001

dx.doi.org/10.1016/j.jog.2011.10.001

http://www.sciencedirect.com/science/journal/02643707

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mailto:[email protected]

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F Bo ReR gion:C Ky-P

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ig. 1. Zonal distribution of the Silurian and Devonian deposits of Viet Nam. 1. Bac

egion: 2a. Dien Bien-Nghe An Zone; 2b. Binh Tri Thien Zone. 3. South Viet Nam Rehay Fault; II. Dien Bien-Lai Chau Fault; III. Song Ma Fault; IV. Rao Nay Fault; V. Tam

nd Devonian stratigraphy have also been obtained recently, andontribute to processing the sequence of some sections and com-leting their distribution areas based on new discoveries.

The Silurian is characterized by marine deposits only, with deepater facies in some regions and areas and shallow-water facies in

thers. In contrast, the Devonian mainly comprises continental andhallow-water marine deposits, and deep-water like facies of thepper Devonian in some areas. The difference between the various

edimentary components and facies of the deposits depends on theistribution areas that reflect the paleoenvironment conditions ofheir sedimentary deposition processes. On the basis of the litho-ogical components and facies, the distribution of the Silurian andevonian deposits can be differentiated into regions and zones as

ollows (Fig. 1):

. The Bac Bo Region (Northern Region) extends over almost all theNorthern part of the country (the Tonkin of older publications).It is limited in the West by the Song Ma and Dien Bien-Lai Chaufaults and includes three zones:1a. The Quang Ninh Zone includes the northeast coastal area of

Bac Bo, including the islands of the Ha Long Bay;1b. The Eastern Bac Bo Zone extends eastward from the Song


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Chay fault and is limited by the Quang Ninh Zone in the East;1c. The Western Bac Bo Zone is located between the Song Chay

Fault in the East, the Dien Bien-Lai Chau Fault in the West,and Song Ma Fault in the Southwest.

gion: 1a. Quang Ninh Zone; 1b. East Bac Bo Zone; 1c. West Bac Bo Zone. 2. Viet-Lao 3a. Trung Bo Zone; 3b. West Nam Bo Zone. Regional and zonal boundaries: I. Songhuoc Son Fault.

2. The Viet-Lao Region, which is located between the Song Ma andDien Bien – Lai Chau Fault in the Northwest and the Tam Ky –Phuoc Son Fault in the South, is divided into two zones – the DienBien – Nghe An and Binh Tri Thien zones, respectively.2a. The Dien Bien-Nghe An Zone extends from the Dien Bien-Lai

Chau and Song Ma Faults in the Northern and Eastern sidesand the Rao Nay Fault in the South.

2b. The Binh Tri Thien Zone is located between the Rao Nay Faultin the North and the Tam Ky-Phuoc Son one in the South.

3. The South Viet Nam Region, which extends southward from theTam Ky-Phuoc. Son Fault, includes two zones that are separatedby a presumed boundary.3a. The South Trung Bo Zone (Southern part of the Central Viet

Nam) extends from the Tam Ky-Phuoc Son Fault to the EastNam Bo area.

3b. The Western Nam Bo Zone includes the territory of KienGiang Province and the Vietnamese part of the Gulf ofThailand.

The stratigraphic units will be presented below for each regionand its respective zone.

2. Stratigraphic units


2.1. Silurian

See (Fig. 2).

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Fig. 2. The distribution in regions and zone

.1.1. Bac Bo region

.1.1.1. Quang Ninh Zone. In the Quang Ninh Zone, the mostmportant Silurian deposits are distinguished by deep-water faciesontaining graptolite faunas and form the upper part of therdovician-Silurian formations in the northeastern coastal area and

n the Co To archipelago. The shallow-water deposits containingenthic fauna are exposed in a small area of the Kien An District, inhe vicinity of Hai Phong City.

The Tan Mai Formation (O-S tm) is characterized by rhythmicnd banded structures, including terrigenous sediments. It is about

km broad an extends discontinuously for hundreds of kilome-ers along the southeast side of the NE-SW trending Yen Tu–Tienen–Tan Mai Fault, and crops out in the Cai Chien and Vinh Thuc

slands.The stratotype of the formation extends along the road from

ong Cai Town through Tan Mai to Than Pun villages. It has beenubdivided into two parts: the lower one is 1000–1200 m thick andomprises grey, greenish-grey, fine- to medium-grained quartziticicaceous sandstone with flattened pebbles interbedded withicaschist, micaceous siltstone, and phyllite. The latter gradually

ncreases upwards in the section. In the upper part (about 1000 mhick) occur green-grey mica schist, micaceous phyllite withome interbeds of micaceous sandstone. Graptolites (Bohemograp-us tenuis, Lobograptus cf. crinitus, Neoculograptus inexpectatus,ristiograptus pseudodubius) occur in the siltstone of the upper partlong with sporomorphs (Acanthotriletes sp., Lophozonotriletes sp.,imozonotriletes sp., Stenozonotriletes sp., and Punctatisporites sp.),otably in the Nam Ha–Truong Thu section. Silurian fossils havelso been found in the upper part of the formation. Yet the Ordovi-ian age of this part is only inferred from the thickness of beds


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hat underlie the Silurian fossiliferous layers (Nguyen Cong Luong,001a,b).

The Co To Formation (O-S ct) is mainly characterized by polymic-ic, cross-bedded sandstone bearing fragments of felsic effusives,

e Silurian and Devonian Units of Viet Nam.

claystone with banded and rhythmic structure, and tuffaceousinterbeds and gritstone. It is therefore readily distinguished fromthe Tan Mai and Phu Ngu formations of the same age. The totalthickness of the Co To Formation reaches over 1000 m (Fig. 3).

The Co To Formation occurs on over 40 islands and islets of Co ToArchipelago, situated in the extreme northeast of Bac Bo (Tonkin)Gulf. It extends along a NE–SW trend, from Lo Chuc San, throughThanh Lan to Co To Islands.

The 710 m thick Thanh Lan Section is composed of two parts:the lower part is composed of mixed deep marine sediments inter-calated with shallow marine facies, and the upper part, made up byfine-grained, banded sediments that indicate deep marine facies.Early Silurian graptolites (Streptograptus exiguus, Monograptus pri-odon) have been collected from the silty claystone of the uppermostlevels of the lower part. Apart from these species, other graptoliteswere also reported from Co To Island (Spirograptus cf. minor, S. cf.turriculatus, S. cf. regularis, Oktavites aff. O. planus, Campograptuscommunis, Demirastites sp., Climacograptus sp., Monograptus ex gr.pandus, Streptograptus sp. (Tran Van Tri et al., 1972, 1975, 1977).Con Ngua Island also yielded Pristiograptus cyphus, Pristiograptussp., Pseudoclimacograptus sp. (in Nui Nhon Islet), and Demirastritestriangularis (Nguyen Huy Mac and Pham The Hien, 1972), and LoChuc San Island yielded Streptograptus exiguous and Monoclimacislinarsoni. All these graptolites indicate an Early Silurian age andare located in the lower beds of the upper part of the formation.The unfossiliferous lower part is rather thick, consisting of deepmarine sediments and possibly corresponds to a relatively longperiod; therefore, the Co To Formation is approximately consid-ered as Ordovician–Early Silurian in age (Tong-Dzuy Thanh and VuKhuc (2006).


The Kien An Formation (S4 kn) crops out in several hills in the KienAn District, near Hai Phong City (Fig. 4). According to Tong-DzuyThanh et al. (2001) the tripartite sequence of the Kien An Forma-tion consist of a 120 m thick lower part of blue-grey marl, mudstone

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https://www.researchgate.net/publication/256714888_Late_Silurian_marine_shelly_fauna_of_Central_and_Northern_Vietnam?el=1_x_8&enrichId=rgreq-e809e99f168b313b450cad79320e6be1-XXX&enrichSource=Y292ZXJQYWdlOzI1OTEyMjkyODtBUzoyODg3OTUzMDQ5NzIyOTFAMTQ0NTg2NTU3NTA0Mw==

https://www.researchgate.net/publication/292752355_Mot_so_van_de_dia_chat_o_quan_dao_Co_To_va_lan_can_trong_vinh_Bac_Bo_Some_geological_problems_of_Co_To_Archipelago_and_adjacent_islands_in_the_Bac_Bo_Gulf?el=1_x_8&enrichId=rgreq-e809e99f168b313b450cad79320e6be1-XXX&enrichSource=Y292ZXJQYWdlOzI1OTEyMjkyODtBUzoyODg3OTUzMDQ5NzIyOTFAMTQ0NTg2NTU3NTA0Mw==




F e: 1–31 t) (The

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ig. 3. Correlation of the Silurian deposits in the Bac Bo Region. (A) West Bac Bo Zon–5. Phu Ngu Formation (O-S pn); (C) Quang Ninh Zone: 1–4. Co To Formation (O-S c

nd yellowish-grey sandstone containing Nikiforovaena cf. ferga-ensis and indeterminate rugosans, and a 320 m. thick middle partomposed of grey, quartzitic sandstone with dark purplish-redudstone interbeds which yields Retziella weberi, Nikiforovaena

erganensis and Howellella sp. The upper part of the section, onhe north slope of Xuan Son Mountain, consists of about 100 m ofhick-bedded dark grey limestone with shale and marl interbedsn the uppermost layers, which yield an abundant Retziella weberissemblage. At the same level, but on the north slope of Tien Hoiountain, the brachiopods Retziella weberi, Nikiforovaena ferganen-

is, Howellella bragensis, Howellella sp. (Vu Khuc and Bui Phu My,990) were recorded, along with abundant corals, notably Favositesdmirabilis, Xiphelasma sp., Nipponophyllum sp., and Mesofavositesp.

No lower boundary of the Kien An Formation has ever beenbserved, and its relations with the Co To and Tan Mai Formationre unknown. It possibly unconformably underlies the Lower Devo-ian Van Canh Formation. The Kien An Formation is referred to theate Silurian, (Late Ludlow or Pridolian) (Tong-Dzuy Thanh et al.,001).

.1.1.2. Eastern Bac Bo Zone. In Eastern Bac Bo Zone, the Silurianeposits are represented by deep-water facies containing graptolite


doi:10.1016/j.jog.2011.10.001

aunas which occur in the central area of the zone. They make uphe upper part of the Ordovician-Silurian Phu Ngu Formation.

The Phu Ngu Formation (O-S pn) is characterized by banded,ainly fine-grained rhythmic terrigenous sediments interbedded

. Sinh Vinh Formation (O3-S sv); 4. Bo Hieng Formation (S4 bh); (B) East Bac Bo Zone: legends in this figure are for Fig. 6 and Fig. 9 also).

with effusives of mafic to felsic and alkaline composition (Fig. 3).The Formation occurs in two bands, the first of which extends fromDai Tu (Thai Nguyen Province) to Cho Ra (Bac Can Province). Thesecond band extends from Luong Mt through Ngoi Nac, Vinh Tuyto Huong Son areas (Ha Giang Province).

With a thickness of 2300–2400 m, the Phu Ngu stratotype iscomposed of two distinct parts. The 1100 m thick lower partincludes argillaceous shale, cherty-argillaceous shale rhythmicallyinterbedded with silty sandstone, locally with lenses of lime-stone and mafic effusives. The 1200 m thick upper part comprisessilty sandstone interbedded with argillaceous shale and cherty-argillaceous shale, locally with lenses of limestone and felsiceffusives. Graptolites (e.g., Climacograptus sp., Glyptograptus sp.,Monoclimacis sp.) have been collected from the uppermost lev-els of the lower part, along with poorly preserved trilobites andbrachiopods (Fig. 3).

In Na Ri area (Bac Can Province), the formation occurs in smallexposures with a thickness of about 250 m, including grey siltysandstone, greenish-grey marl, black, thin-banded argillaceousshale containing the graptolites Diplograptus sp., Climacograptuslatus, Climacograptus cf. C. scolaris, Ptilograptus sp., Glyptograptussp., the trilobites Agnostus perrugatus, Remopleurides aff. R. salteri,and the bryozoan Fenestella sp.


All these fossils are of Ordovician to Early Silurian age, but occurin a fairly low position in the sections, but the part the section thatoverlies the fossil-bearing beds is rather thick and characterizedby deep marine facies, therefore the formation can reasonably be

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Tong-Dzuy T. et al. / Journal of Geodynamics xxx (2011) xxx– xxx 5

er Sil

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Fig. 4. Distributed area (A) and stratigraphic sequence (B) of the Upp

ated as Ordovician-Silurian (Pham Dinh Long, 2001; Nguyen Kinhuoc, 2001; Tong-Dzuy Thanh and Vu Khuc, 2006).

.1.1.3. Western Bac Bo Zone. In the Western Bac Bo Zone the Sil-rian deposits include the upper parts of the Ordovician-Silurianinh Vinh Formation, and the Upper Silurian Bo Hieng Formations.hey mainly consist of shallow-water facies deposits, and deep-ater deposits are limited to the west of Son La Province (Ket Hay

ormation).The Sinh Vinh Formation (O3—S sv) (Fig. 3) is mainly character-

zed by light grey, thickly bedded dolomitic limestone, exposedn the lower section of the Song Da River in discontinuous nar-ow bands. In the Sinh Vinh Section, along the Song Da River, theormation is clearly distinguished by the three following parts:1) The 40 m thick lower part, made up by conglomerate, whoseuartzite pebbles are derived from the underlying Ben Khe For-ation; (2) The 400 m thick middle part, made up by calcareous

andstone and mudstone, dolomite, sandy limestone and marlearing the corals Reuschia sp., Plasmoporella kiaeri, Favositella alve-lata; (3) The 350 m thick upper part, which consists of light grey,hickly bedded dolomitic limestone and calcareous shale interbedsearing the corals Favosites sp., F. aff. F. forsbesi, F. ex gr. F. goth-


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andica, F. cf. F. hisingeri, F. cf. F. coreaniformis, Mesofavosites sp.,quameofavosites sp., and Parastriatopora sp. The total thickness ofhis section is 800 m, but in other sections its thickness reaches000–1200 m.

urian Kien An Formation (S4 kn) in Kien An District (Hai Phong City).

Apart from the above mentioned fauna, some other fossils havebeen collected, such as the corals Reuschia sp., Favositella alveolata,and Favosites sp., F. aff. F. forbesi var. similis, F. ex gr. F. gothlandicus,F. cf. F. hisingeri, F. cf. F. coreaniformis, Squameofavosites sp., Meso-favosites sp., Parastriatopora sp., Multisolenia ex gr. M. tortuosa, andthe crinoid Bistrowicrinus quinquelobatus.

The Bo Hieng Formation (S4 bh) is distributed in the limited areaof the lower section of the Song Da River basin, and it conformablyrests upon the Sinh Vinh Formation and under the Lower DevonianSong Mua Formation (Fig. 3).

The 400 m thick Bo Hieng Formation, mainly consists ofdark green marly shale interbedded with black-grey limestoneand, in its lower part, some banded argillaceous shale contain-ing brachiopods (Retziella weberi, Orbiculoidea tonkinensis), andbivalves (Modiomorpha brevis, M. sp., Cymatonota cf. C. yunnanen-sis, Dysodonta sp., Actinopteria sp.). The upper part is composed ofblack, thin- to medium-bedded limestone and marl in the upperpart, containing Retziella weberi, Tadschikia xuanbaoi, Howellellasp., Scoliopora sp., and Favosites kunjakensis (Ta Hoa Phuong andLe Van Manh, 1996).

In the Nui Tau Mt Section (Yen Lap, Phu Tho Province), theblack-grey limestone interbedded with argillaceous shale yielded


corals (Palaeofavosites aff. balticus, Favosites kernihoensis, Aphyl-lum aff. sociale) and brachiopods (Retziella weberi, Ferganella aff.Turkestanica) (Nguyen Huu Hung et al., 1988), which indicate a LateSilurian age of the formation (Tong-Dzuy Thanh et al., 2001). The

dx.doi.org/10.1016/j.jog.2011.10.001


https://www.researchgate.net/publication/292751309_Tai_lieu_moi_ve_tram_tich_Silur_thuong_va_Eifel-Givet_trong_to_Thanh_Son-Thanh_Thuy_New_data_on_Upper_Silurian_and_Eifelian-Givetian_sediments_in_Thanh_Son_-_Thanh_Thuy_sheet?el=1_x_8&enrichId=rgreq-e809e99f168b313b450cad79320e6be1-XXX&enrichSource=Y292ZXJQYWdlOzI1OTEyMjkyODtBUzoyODg3OTUzMDQ5NzIyOTFAMTQ0NTg2NTU3NTA0Mw==

https://www.researchgate.net/publication/292753638_Nhung_tai_lieu_moi_ve_mat_cat_chuan_cua_he_tang_Bo_Hieng_New_data_on_the_stratotype_of_Bo_Hieng_Formation?el=1_x_8&enrichId=rgreq-e809e99f168b313b450cad79320e6be1-XXX&enrichSource=Y292ZXJQYWdlOzI1OTEyMjkyODtBUzoyODg3OTUzMDQ5NzIyOTFAMTQ0NTg2NTU3NTA0Mw==




f the

lt

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Fig. 5. Distributed area and stratigraphic sequence o

ithology and fauna of the Bo Hieng Formation is similar to that ofhe Kien An Formation described above.

The Ket Hay Formation (S1-2 kh) occurs in a narrow band in theouthwestern area of Son La Province and discontinuous exposuresorthwestward from Son La to Tuan Giao, all of them being proba-ly in close relation to the Song Ca Formation (see below—Viet-Laoegion). The 230 m thick Ket Hay Formation consists of thin-edded siliceous shale, interbedded with siliceous siltstone, shale,ericite-chlorite schist, and calcareous-siliceous schist. Most of theraptolites it has yielded (Demirastrites triangulates, Hedrograptusf. H. rectangulatus, Diplograptus cf. D. modestus) are Early Siluriann age (Le Thanh Huu and Vu Xuan Luc, 2005; Tran Van Tri and Vuhuc, 2009).

.1.2. Viet-Lao Region


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The Silurian deposits in the Viet-Lao region include the upperart of the Ordovician-Silurian Song Ca Formation, and the Tayrang Formation of Late Silurian-Early Devonian age in the Dienien-Nghe An Zone. In the Binh Tri Thien Zone, they are composed

Silurian Dai Giang Formation in Quang Tri Province.

of the upper part of the Ordovician-Silurian Long Dai Formation,and the Upper Silurian Dai Giang Formation.

2.1.2.1. Dien Bien-Nghe An Zone. The Song Ca Formation (O3-S2 sc)crops out along two main strips, the first of which extends fromMuong Xen and Tuong Duong to Quy Chau, Nghe An Province,south of the Song Ca River. The second strip extends from theVietnam-Laos border through Nghe An to Ky Anh, Ha Tinh Province.The formation is about 2100–2300 m thick and mainly consistsof argillaceous shale, sandstone, and some beds of black, andbedded limestone. The graptolites Monoclimacis vomerinus andPristiograptus kweichihensis occur in the argillaceous shale of itsupper part, and indicate an Early Silurian age. Besides, some Sil-urian spores also occur in this formation, such as Zonosphaeridiumsp. and Leiotrichoides sp. Since the Early Silurian graptolites occurin the upper part of the formation, its lower part may therefore


tentitavely be referred to the Upper Ordovician (Tong-Dzuy Thanhand Vu Khuc, 2006).

The Tay Trang Formation (S3-D2e tt) is distributed in Lai Chau andDien Bien areas, Northwest Bac Bo, extending to the West of Nghe

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n Province (North Trung Bo), so it includes all the componentsf the Tay Trang Formation introduced by Dovjikov et al. (1965)nd the Huoi Nhi Formation erected by Nguyen Van Hoanh (Leuy Bach and Nguyen Van Hoanh, 1995); therefore, the Tay Trangame has priority.

The 800 m thick Tay Trang Formation consists of: (1) 540 m thickrey, fine- to middle-grained sandstone, interbedded with ash greyo dark grey, thin-bedded siltstone, and dark grey clay shale; (2)60 m thick, dark grey, thin bedded clay shale, dark grey siltstoneith some dark grey, and fine-grained, thin bedded sandstone. The

ormation yields fossils that indicate an age ranging from the Lud-ow (Silurian) to the Eifelian (Middle Devonian). They include, inhe West of Nghe An Province, graptolites (Bohemograptus bohemi-us, Monograptus thomasi, M. yukonensis, M. uniformis) (Nguyen Vanhuc, 1998), and dacryoconarids (Nowakia cancellata, N. holynensis,omoctenus sp.), and, in the Tay Trang area (Dien Bien Province,estern Bac Bo Zone), cephalopods (Erbenoceras sp., Anetoceras

p.), the dacryoconarid Nowakia sp. (cf. N. acuaria), and the bra-hiopod Chonetes ex gr. tenuicostata. The Tay Trang Formation (=uoi Nhi Fm.) rests unconformably upon the Song Ca Formation

O-S sc) and conformably under the Huoi Loi Formation (D1-2 hl)Tong-Dzuy Thanh and Vu Khuc, 2006).

.1.2.2. Binh Tri Thien Zone. The Long Dai Formation (O2-S2 ld) com-rises terrigenous sediments of rhythmic structure, interbeddedith acidic to intermediate effusive, exposed in the south of the Raoay Fault. In the Ban Ho–Vit Thu Lu stratotype, the formation is up

o 1250 m thick, and its lower part (about 1000 m thick) consistsf rhythmic intercalation of sandstone, siltstone and argillaceoushale, clay-cherty shale with some interbeds of andesite, whichield the Late Ordovician trilobites Cyclopyge sp., Microparia (?)agaviaformis, Ogygiocaris sp., Nileus sp., and the graptolite Diplo-raptus sp. Its upper part is composed of black argillaceous shale,lay-chlorite shale with some interbeds of sandstone and gritstoneontaining the Late Silurian graptolites Neodiversograptus nilssoni,onograptus sp., and Pristiograptus sp. The Le Ky section, which

eaches 1930 m in thickness, displays the same lithological com-onents, but begins with 90 m thick conglomerate beds, and isistinguished by the tuffaceous sandstone in its middle part, andhe lack of andesite interbeds. Llandovery graptolites (Demirastritesonvolutus, Monograptus halli, Oktavites spiralis) have been collectedrom the middle part of the section, whereas its upper part yieldsohemograptus bohemicus, Monoclimacis sp. (Nguyen Xuan Duong,996; Tong-Dzuy Thanh and Vu Khuc, 2006).

The Dai Giang Formation (S3-4 dg) is exposed in the Quanginh and Quang Tri Provinces, with thickness of about 1100 mFig. 5), and its sequence begins with gritstone and coarse-grainedandstone, unconformably overlying the Long Dai Formation. Theormation consists essentially of sandstone, siltstone and calcare-us sandstone, with limestone and marl beds in its upper part.

benthic fauna has been collected mainly from the middle andhe upper parts of the formation, and includes trilobites (Cro-us beaumonti, Metacalymene sp., Praedechenella aff. vietnamica,

ncrinurus cf. sinicus), brachiopods (Retziella weberi, R. altaica,ikiforovaena vietnamica, “Howellella” cf. lynxoides), corals (Multi-

olenia cf. formosa, Nipponophyllum anmaense), bivalves (Schizodus?yducensis, Sphenotus antecedens, Modiomorpha paracrypta, Gonio-

hora dianensi), and fish remains referred to the placodermyducosteus anmaensis and an indeterminate acanthodian (Nguyenuan Duong, 1996; Tong-Dzuy Thanh and Vu Khuc, 2006).

.2. Devonian


doi:10.1016/j.jog.2011.10.001

See (Fig. 2; Fig. 6).Devonian deposits are widespread in Viet Nam, but their lithol-

gy and sequences, especially in the Lower Devonian, are different

PRESSynamics xxx (2011) xxx– xxx 7

in the Bac Bo, Viet-Lao, and South Viet Nam regions. The most com-plete Devonian sections are observed in the Bac Bo region, whereasseparate, discontinuous sections are met with only in some areas ofthe South Viet Nam region (Tong-Dzuy Thanh and Vu Khuc, 2006).

In the Bac Bo region, the resemblances between the Devoniansections is conspicuous and well characterized, both lithologicallyand faunally, thereby indicating that they were formed in a single,large basin. In the Quang Ninh, Eastern Bac Bo and Western BacBo zones, the Devonian sections are composed of two conspicuousparts, the lower one mainly consisting of terrigenous sediments,and the upper one of carbonate. However, detailed differencesbetween these sections can be noticed. Notably, in the Eastern theBac Bo Zone, the Lower Devonian is characterized by Red Beds thatunconformably overly the Lower Paleozoic, while in the WesternBac Bo there is a conformity between the Upper Silurian Bo HiengFormation and the Lower Devonian Song Mua Formation (Fig. 6).

2.2.1. Bac Bo Region2.2.1.1. Quang Ninh Zone. In the Quang Ninh Zone, the Devoniandeposits consist of the Van Canh, Duong Dong, Do Son, and TrangKenh Formations, successively. The uppermost of the Devoniansequences in this zone displays the lowermost part of the UpperDevonian-Lower Carboniferous Con Voi and Pho Han formations.

The Van Canh Formation (D1 vc) is the lowermost formation ofthe Devonian sequence in the Quang Ninh Zone, and crops out inthe Van Canh islet, Tra Ban, Ngoc Vung, and other islands in the BaiTu Long (Fai Si Lung) Bay, and on the Do Son Peninsula (Nguyen HuuHung et al., 2007). In the Van Canh type section, the formation con-sists of a 200 m thick series of alternating sandstone and mudstonebeds, which contains plant remains (Tainiocrada? sp. cf. T. decheni-ana, and Psilophytites? sp.). In this section, the Van Canh Formationconformably underlies the Duong Dong Formation, which yieldsthe brachiopod Tulynetes nonpoensis.

On the Do Son Peninsula, the Van Canh Formation uncon-formably underlies the Do Son Formation. In previous works,the Ngoc Xuyen mudstone and sandstone that has yielded theeurypterids Rhinocarcinosoma dosonensis and Hughmilleria sp., iso-lated placoderm fish plates (referred to a primitive antiarch and a“Wangolepis”-like placoderm) (Brady et al., 2002), and Lower Devo-nian sporomorphs, were considered as the lower part of the DoSon Formation (Tong-Dzuy Thanh and Vu Khuc, 2006). They arenow referred to the Van Canh Formation (Nguyen Huu Hung et al.,2007), but their eurypterid and vertebrate fauna seems more sug-gestive of the Uppermost Silurian (Brady et al., 2002; Janvier et al.,2003).

The Duong Dong Formation (D1–D2 e dd) is exposed in Kinh Mon(Hai Duong Province), Duong Dong (Trang Kenh, Hai Phong City)and Dong Trieu (Quang Ninh Province), and in Chau Dop, Tra Ban,and Ngoc Vung islands (Ha Long Bay).

The new data provided by Nguyen Huu Hung et al. (2007) showthat the crossbedded quartzitic sandstone, siltstone and shale of theupper part of the Duong Dong Formation described in the previousworks (Tong-Dzuy Thanh and Vu Khuc, 2006) should be referredto the overlying Do Son Formation, and that the brachiopod- andcoral-bearing limestone lenses of its uppermost beds belong infact to the Trang Kenh Formation. This accords with the origi-nal description of the formation by Nguyen Quang Hap (1967).According to Nguyen Huu Hung et al. (2007), the Duong Dong For-mation in the Lo Son area consists of: (1). 50 m thick clay shaleand mudstone containing brachiopods; (2) 70 m thick fine-grainedsandstone and interbeds of shale containing brachiopods, and (3)80 m thick fine-grained sandstone, mudstone interbeds contain-


ing poorly preserved brachiopods. The fossils from the DuongDong Formation are mainly brachiopods, and have been collectedfrom many localities, such as the Lo Son, Duong Dong and HiepSon (Kinh Mon) areas, and on Ngoc Vung and Van Canh islands

dx.doi.org/10.1016/j.jog.2011.10.001

https://www.researchgate.net/publication/222493984_Devonian_fish_Placodermi_Antiarcha_from_Tra_Ban_Island_Bai_Tu_Long_Bay_Quang_Ninh_Province_Vietnam_and_the_question_of_the_age_of_the_Do_Son_Formation?el=1_x_8&enrichId=rgreq-e809e99f168b313b450cad79320e6be1-XXX&enrichSource=Y292ZXJQYWdlOzI1OTEyMjkyODtBUzoyODg3OTUzMDQ5NzIyOTFAMTQ0NTg2NTU3NTA0Mw==


https://www.researchgate.net/publication/230214047_A_New_Carcinosomatid_Eurypterid_From_The_Upper_Silurian_Of_Northern_Vietnam?el=1_x_8&enrichId=rgreq-e809e99f168b313b450cad79320e6be1-XXX&enrichSource=Y292ZXJQYWdlOzI1OTEyMjkyODtBUzoyODg3OTUzMDQ5NzIyOTFAMTQ0NTg2NTU3NTA0Mw==





Fig. 6. Correlation of the Devonian deposits in the Bac Bo Region. (A) West Bac Bo Region: 1. Upper Silurian Bo Hieng Formation (S4 bh); 2. Song Mua Formation (D1 sm); 3.Ban Nguon Formation (D1 bn); 4. Ban Pap Formation (D1p-D3fr bp); 5. Bang Ca Formation (D2gv-D3fr bc); 6. Toc Tat Formation (D3fm-C1t tt). (B) East Bac Bo Zone: 1. OrdovicianLutxia Formation unconformably is underlying the Si Ka Formation; 2. Si Ka Formation (D1 sk)—Red beds containing vertebrate remains; 3. Bac Bun Formation (D1 bb); 4. MiaLe Formation (D ml) containing abundant Pragian benthos of the Euryspirifer tonkinensis assemblage; 5. Ban Pap Formation (D p-D fr bp); 6. Bang Ca Formation (D gv-D frb n Form4

(tSrvPDmr

PtDptbd2isri

-

1

c); 7. Toc Tat Formation (D3fm-C1t tt). (C) Quang Ninh Zone: 1. Upper Silurian Kien A. Do Son Formation (D2gv-?D3fr ds); 5. Trang Kenh Formation (D2gv-D3 tk.

Bai Tu Long Bay). The brachiopods are referred to Euryspirifer cf.onkinensis, Indospirifer kwangsiensis, Schellwienella cf. S. lantenoisi,tropheodonta cf. S. interstrialis, Athyris concentric, Atrypa ex gr.eticularis, Bacbochonetes sp., Retichonetes sp., Bacbochonetes jan-ieri, Perichonetes mutabilis, and occur along with the bivalvesterinopecten sp. Carinatina cf. C. arimaspa, Desquamatia sp. Theuong Dong Formation conformably overlies the Van Canh For-ation, and unconformably underlies the Do Son Formation. It is

eferred to the Lower Devonian—Eifelian.The Do Son Formation (D2gv-?D3fr ds) crops out in the Do Son

eninsula and some islands of Bai Tu Long Bay. On the mainland ofhe Quang Ninh Zone, it is usually exposed along with the Duongong Formation and has sometimes been incorrectly referred toart of the latter. It was first described by Lantenois (1907) ashe “Do Son Sandstone” (Grès de Do-Son), which occurs along theeaches of Do Son Peninsula (Hai Phong City). Later, it has beenescribed as a tripartite formation (Tong-Dzuy Thanh and Vu Khuc,006). Our new investigations show that the Do Son Formation

ncludes two parts which correspond to Lantenois’s “Do Son Sand-tone”, and a lower part of the “tripartite formation”, which is noweferred to the Van Canh Formation. The sequence of the formations thus as follows:

150–200 m thick, thick-bedded, locally cross-bedded quartzgravelstone at the base, overlain by quartzitic sandstone, coarse-grained sandstone, sometimes with interbeds of chocolate-coloured siltstone. This member is most clearly exposed at theback of the Do Son Market and along the road towards Beach


doi:10.1016/j.jog.2011.10.001

2, particularly around the Van Huong Quay. Some bivalves, suchas: Schizodus (?) sp., Ptychopteria (Actinopteria) hunanensis andGoniophora sp. were collected on the mountain slope situated inthe back of the hamlet lying between the Do Son Market and the

1 3 2 3

ation (S4 kn); 2. Van Canh Formation (D1 vc); 3. Duong Dong Formation (D1-D2e dd);

main office of the Do Son Townlet. Vertebrate remains (Vietna-maspis trii, Briagalepis sp., Bothriolepis cf. B. gigantea) have beenfound along with the lycophyte Bergeria or Knorria (cf. Lepidoden-dropsis sp.) on the shore of the Van Huong Quay area (Janvier andTong-Dzuy Thanh, 1998; Long et al., 1990; Tong-Dzuy Thanh andCai Chong-yang, 1995).

- 200 m thick, brown, medium-bedded, locally cross-bedded sand-stone, dark chocolate-coloured siltstone interbedded with grey,greenish-grey, yellow-brown weathering clay shale,. This barrenmember is clearly visible on the road towards the Casino build-ing, from near the “Bao Dai Villa” to the southernmost end of thepeninsula.

The sedimentology and fossils of the Do Son Formation indicatea deltaic to coastal facies. However, the outcrops of this formationare scattered over a large area and display a great diversity of faciesthat is characteriztic for deltaic environments. Therefore it deservesinvestigation.

The unconformity between the Do Son Formation and theunderlying Duong Dong Formation is only suggested by the pres-ence of gravelstone beds at the base of the former formation, but isconformably underlying the carbonate Trang Kenh Formation.

The Trang Kenh Formation (D2gv-D3 tk) is largely distributed inthe Quang Ninh Zone, including islands of Ha Long Bay, and con-sists of limestone containing abundant corals, stromatoporoids andsome brachiopods. In previous works, the Trang Kenh Formationwas described as a tripartite unit, which is composed of two lime-stone parts, and a middle cherty part. Its total thickness varies


from 250 m to 300 m. The new study by Nguyen Huu Hung et al.(2007) shows that this formation only consists of limestone, thecherty part belonging in fact to the Pho Han Formation of UpperDevonian-Lower Carboniferous age. The Trang Kenh Formation

dx.doi.org/10.1016/j.jog.2011.10.001

https://www.researchgate.net/publication/233087357_A_new_bothriolepid_antiarch_Pisces_Placodermi_from_the_Devonian_of_Do_Son_Peninsula_northern_Vietnam?el=1_x_8&enrichId=rgreq-e809e99f168b313b450cad79320e6be1-XXX&enrichSource=Y292ZXJQYWdlOzI1OTEyMjkyODtBUzoyODg3OTUzMDQ5NzIyOTFAMTQ0NTg2NTU3NTA0Mw==

IN PRESSG Model

G

f Geodynamics xxx (2011) xxx– xxx 9

ydcHactshFHbV

sNHswgFfcmcmtmbKtaV

2Sm

fwo(ifilaetXSrp“abtnPAdivsfyD



ields Amphipora ramosa, A. rudis, Crassialveolites crassus, Scolioporaenticulata, Caliapora battersbyi, Alveolites admirabilis, and the bra-hiopod Stringocephalus burtini, which all suggest a Givetian age.owever, the upper part of the formation yields stromatoporoidsnd corals (Amphipora laxeperforata, A. pervesiculata, Stachyodesostulata, S. fasciculate, which indicate a Givetian-Frasnian age. Inhe Phuc Son–Nui Han area, Famennian conodonts (Palmatolepisubperlobata, P. triangularis, P. glabra glabra, P. subrecta, P. perlobata)ave been recorded from the uppermost beds of the Trang Kenhormation (Tong-Dzuy Thanh and Vu Khuc, 2006; Nguyen Huuung et al., 2004). The Trang Kenh Formation conformably restsetween the underlying Do Son Formation, and the overlying Conoi and Pho Han Formations, which are described below.

The Con Voi Formation (D3fm-C1 cv) mainly consists of lime-tone and some thin beds of siliceous limestone that occur in the Mtui Con Voi Kien An and An Lao Districts, Hai Phong City. The Phoan Formation (D3fm-C1 ph) includes limestone, siliceous lime-

tone and chert in Cat Ba Island (Ha Long Bay), and is the coevalith the Con Voi Formation. These two formations are thus distin-

uished by siliceous components: some thin beds in the Kien Anormation, and more diffuse ones in the Pho Han Formation. Theauna of the Con Voi Formation mainly consists of brachiopods,orals, and some foraminifera, whereas that of the Pho Han For-ation includes many conodonts and a rich benthic fauna, such as

orals (Fuchungopora sp., Syrigopora distans, Tetraporinus sp.) andany brachiopods in the lower beds of the formation. Both forma-

ions were dated as Upper Famennian-Lower Carboniferous, butost of them are Lower Carboniferous in age, their Famennian part

eing negligible in the sections and may be referred to the Trangenh Formation. It is possible that the Con Voi and Pho Han Forma-

ions represent different sections of a single formation that displays variable number of siliceous components (Tong-Dzuy Thanh andu Khuc, 2006).

.2.1.2. Eastern Bac Bo Zone. The Song Cau Group (D1 sc) includes thei Ka Formation (red, subcontinental facies) and the Bac Bun For-ation (deltaic facies grading upwards into shallow marine facies).The Si Ka Formation (D1 sk) is exposed in the Viet Nam–China

rontier areas of Ha Giang Province and in Lang Son Province,hereas in the Cao Bang and Thai Nguyen Provinces, it is composed

f part of the sequences of the Song Cau Group. In its stratotypeFig. 3), the Si Ka Formation consists of greenish-grey siltstonenterbedded with clay shale, greenish marly shale, thin-bedded,ne-grained limestone, and grey siltstone with interbeds of vio-

et chocolate marly shale. The total thickness of the formation isbout 650 m. According to Hoang Xuan Tinh, the basal conglom-rate beds are locally up to 5–10 m and met with in the frame ofhe Geological Map (1:200,000) of the Bao Lac Map sheet (Hoanguan Tinh, 2001). Its sections are also observed in Dong Mo (Langon Province) and Trang Xa (Thai Nguyen Province), where theed sandstone is an important component in the sequence. Earlyublications on this formation briefly mentioned (e.g., the fishesAsterolepis” sp., “Homosteus” sp., and the plant “Bythotrephis aff.ntiquate” (Saurin, 1956). During the last two decades the verte-rates from the Si Ka Formation have been shown to belong tohe two major fish groups that also populate the Lower Davo-ian of southern China, namely the Galeaspida and the antiarchanlacodermi, to which can be added various Sarcopterygii. Neithersterolepis, nor Homosteus have been confirmed in the fauna. Toate, the upper beds of the Si Ka Formation consisting of sandstone

n Thai Nguyen Province has yielded the galeaspid Bannhuanaspisukhuci and fragmentary remains of various Polybranchiaspis-like


doi:10.1016/j.jog.2011.10.001

pecies, along with various yunnanolepiform and procondylolepi-orm antiarchs (Procondylolepis sp., Yunnanolepis spinulosa), andoungolepidid sarcopterygian remains (Janvier et al., 1993; Tong-zuy Thanh et al., 1994; Janvier and Ta Hoa Phuong, 1999). The Si Ka

Fig. 7. Lower Devonian Si Ka Formation unconformably rests upon the OrdovicianLutxia Formation (Left cliff on the road Dong Van-Lung Cu (Photo: Ta Hoa Phuong).

Formation unconformably rests upon different levels of the LowerPaleozoic deposits (Fig. 7) and conformably underlies the Bac BunFormation.

The Bac Bun Formation (D1 bb) (Fig. 4) consists of grey, chocolate,variegated weathered clay shale and marly shale, siltstone con-taining vertebrates in the stratotype (Dong Van District, Ha GiangProvince). West of Dong Mo (Lang Son Province), it comprises amember of grey carbonate phosphate containing well-preservedvertebrates, and the overlying clay shale and siltstone member con-tains abundant brachiopods. In Trang Xa (Thai Nguyen Province), itconsists of grey limestone and marly shale containing corals, bra-chiopods and vertebrates. The thickness of the formation variesfrom some tens to 500 metres. The distribution areas of this for-mation are much the same as for the Si Ka Formation, i.e. in the HaGiang, Cao Bang, Lang Son, and Thai Nguyen Provinces.

Vertebrate-bearing faunas of the lower member of theBac Bun Formation include, in the stratotype, the galeaspidsPolybranchiaspis sp. cf. P. liaojaoshanensis, numerous antiarchs(Yunnanolepis deprati, Y. bacboensis, Chuchinolepis dongmoensis,Vanchienolepis langsonensis), the petalichthyid Tongdzuylepis viet-namensis and the sarcopterygian Youngolepis cf. Y. praecursor. TheDong Mo section yields much the same vertebrate fauna with,in addition, a still indetermined lungfish (Tong-Dzuy Thanh andJanvier, 1990, 1994; Tong-Dzuy Thanh and Vu Khuc, 2006). Theupper member of the formation yields brachiopods (Howittiawangi, Cyrtochonetes indosinensis, Parachonetes zeili) (Racheboeufand Tong-Dzuy Thanh, 2000). The lithology and faunal composi-tion of the Bac Bun Formation indicate a littoral to deltaic faciesgrading upwards into a shallow marine facies.

The Mia Le Formation (D1 ml) is widespread in the Eastern zoneof Bac Bo region and consists of greenish-grey siltstone interbeddedwith clay shale and marl, with some thin interbeds of argillaceouslimestone, and grey limestone in its uppermost part (Figs. 6 and 8).The thickness of the formation in the Lung Co–Mia Le stratotype(Dong Van District, Ha Giang Province) reaches 500 m, but in othersections, it can decrease to a few hundred metres, as in the Ha Langarea (Cao Bang Province), where it is only about 200 m. This for-mation is the most fossiliferous unit in the Paleozoic of Viet Nam,containing hundreds of species of corals, brachiopods, trilobites,crinoids, and other groups, all indicating a Pragian age. They arecomponents of the well-known Euryspirifer tonkinensis Assemblage(Tong-Dzuy Thanh and Ta Hoa Phuong, 1994), which is domi-


nated by brachiopods (e.g., Euryspirifer tonkinensis, Undispirifer aff.pseudoaculiatus, Elymospirifer kwangsiensis, Dicoelostrophia anna-mitica, Atrypa aff. reticularis, Schellwienella douvillei, S. lantenoisi,Athyris? tiaomachiensis, Parachonetes zeili) and corals (e.g., Favosites

dx.doi.org/10.1016/j.jog.2011.10.001

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https://www.researchgate.net/publication/291839355_A_new_early_Devonian_galeaspid_from_Bac_Thai_Province_Vietnam?el=1_x_8&enrichId=rgreq-e809e99f168b313b450cad79320e6be1-XXX&enrichSource=Y292ZXJQYWdlOzI1OTEyMjkyODtBUzoyODg3OTUzMDQ5NzIyOTFAMTQ0NTg2NTU3NTA0Mw==

https://www.researchgate.net/publication/291866689_Les_vertebres_Placodermi_Galeaspida_du_Devonien_inferieur_de_la_coupe_de_Lung_Co-Mia_Le_province_de_Ha_Giang_Viet_Nam_avec_des_donnees_complementaires_sur_les_gisements_a_vertebres_du_Devonian_du_Bac_?el=1_x_8&enrichId=rgreq-e809e99f168b313b450cad79320e6be1-XXX&enrichSource=Y292ZXJQYWdlOzI1OTEyMjkyODtBUzoyODg3OTUzMDQ5NzIyOTFAMTQ0NTg2NTU3NTA0Mw==




ng Cu

gclbPm(

bWyiiA((tc1oSscH

Fig. 8. Stratigraphic sequence of the Lower Devonian Lu

oldfussi, F. styriacus, F. pencolei, F. preplacenta, Squameofavositesechicus, Sqf. giganteus, Sqf. sokolovi, Sqf. delicatus, Emmonsia yen-acensis, Squameopora vukhuci, Echyropora grandiporosa, Coenitesulvankerae, Heliolites praeporosus), but also includes the trilobiteroetus sp. and bivalves (e.g., Pterinea mieleensis). The Mia Le For-ation lies conformably between the Bac Bun (D1 bb) and Ban Pap

D1-2 bp) formations (Tong-Dzuy Thanh and Vu Khuc, 2006).The Khao Loc Formation (D1-2 kl) is characterized by its car-

onate composition and is limited to the Khao Loc Structureestward to Ha Giang Province. It consists of 15 m thick dark grey,

ellow-grey, red-brown weathering marl and clay shale contain-ng abundant vertebrates, and 800 m thick, black-grey limestonenterbedded with argillaceous limestone that yield corals andmphipora sp. The vertebrate fauna notably includes galeaspidsPolybranchiaspis liaojaoshanensis, Laxaspis yulongsus), antiarchsYunnanolepis sp., Minicrania lissa, Heteroyunnanolepis qujingensis),he acanthothoracid placoderm Hagiangella goujeti, and the sar-opterygian Youngolepis praecursor (Janvier and Ta Hoa Phuong,999; Racheboeuf et al., 2005). The lowermost limestone bedsf the formation yield corals (e.g., Favosites stellaris, F. vilvaensis,


doi:10.1016/j.jog.2011.10.001

quameofavosites enormis, S. vanchieni, S. baolacensis, S. spongio-us, Thamnopora beliakovi, Cladopora cf. C. yavorskyi, Parastriatoporahampungensis, Caliapora cf. C. primitive) and the brachiopodsowittia wangi and Howellella ex gr. crispa. The middle part of the

-Ma Le section (Dong Van District, Ha Giang Province).

section yields Striatopora sp., Thamnopora kolodaensis, T. cf. T. siavis,Alveolitella cf. A. polenowi, Coenites sp., and Corolites haoi (Tong-Dzuy Thanh et al., 1988; Tong-Dzuy Thanh and Vu Khuc, 2006).

The corals, brachiopods, and vertebrates from the base of theformation are to be correlated with the Bac Bun and Mia Le forma-tions (Lower Devonian), whereas the corals from its middle partindicate a Middle Devonian age.

The Ban Pap Formation (D1p-D3fr bp) is characterized mainly bygrey, thin to medium bedded limestone, widely extending in bothEastern and Western Bac Bo Zones, and will be presented here-inafter for all Bac Bo Region. The total thickness of the formationreaches 1200 m, but in certain sections, it may only be 300–400 mthick.

The lower part of the Ban Pap Formation mainly consists ofdark grey, thin- to medium-bedded, bituminous limestone contain-ing Emsian stromatoporoids and corals, such as Amphipora acerbaalaiskiensis, A. agreste vojachia, Favosites styriacus, F. stellaris, F. reg-ularissimus, Emmonsia yenlacensis, Cladopora yavorskyi.

The middle part of the Ban Pap Formation includes dark grey,medium-bedded, fine-grained limestone, and its upper part grey


to light grey, thick-bedded to massive fine-grained limestone.Although the boundary between the lower and the upper parts isdifficult to identify on the basis of the lithology, their respective fau-nas are readily distinguished. Its middle part yields characteriztic

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ING Model

G

f Geod

Eif

ltroCueAS

PalrsFGctdtt

aGaftD

t3scitlulbV

baLaiGcaTsmZ

(sittti



ifelian fossils, such as the dacryoconarids Nowakia sp., Viriatellinarregularis, V. dalejensis, and the corals Favosites robustus, Squameo-avosites cf. S.kulkovi, and Thamnopora cf. T. micropora.

The upper part of the Ban Pap Formation consists of grey toight grey, thick-bedded to massive fine-grained limestone, con-aining a Givetian fauna, such as the stromatoporoids Amphiporaamose and Actinostroma clatratum, the corals Thamnopora polyg-nalis, T. nicholsoni, Trachypora dubatolovi, Caliapora battersbyi,rassialveolites crassiformis, Coenites quydatensis, Scoliopora dentic-lata, Dendrostella trigemme, Grypophyllum cf. G.carinatum, Macgeax gr. multizonata, and the brachiopods Stringocephalus burtini andtrypa (Desquamatia) sp. Moreover, Early Frasnian species of thetachyodes costulata Assemblage occur in some sections.

It is worth noting that in small areas of Dong Van (Ha Giangrovince) there are limestone, clayish limestone, marl, black shalend chert interbeds, containing numerous pelagic fossils. In theower beds are Lower Devonian fossils (Nowakia acuaria, N. bar-andei, conodonts from the Polygnathus excavatus-Pandorinellinateinhornensis, P. nothoperbonus zones, and there are still the coralsavosites regularissimus and Heliolites sp. In upper beds occurivetian species, such as Palmatolepis varcus and others. Thesearbonate deposits containing pelagic fauna can correlate withhe lower and middle parts of the Ban Pap Formation, and wereescribed as the Si Phai Formation by Dang Tran Huyen (1979), buthey can reasonably be considered as components of a member –he Si Phai Member – within the Ban Pap Formation.

The Ban Pap Formation conformably rests between the Mia Lend Toc Tat Formations. Most of the fauna indicate an Emsian-ivetian age, but in the top part of Dong Van (Ha Giang Province)nd Chi Lang (Lang Son Province) sections, there are Early Frasnianossils; so, the upper boundary of the formation is diachronic, andhe formation should be referred to the Emsian-Frasnian (Tong-zuy Thanh and Vu Khuc, 2006).

Tan Lap Formation (D2gv-D3fr tl) extends over some areas ofhe Chi Lang District, Lang Son Province, and is composed of5–80 m thick conglomerate, arkosic gritstone, and arkosic sand-tone interbedded with black siltstone. In the sandstone wereollected plant remains that resemble Bergeria or Knorria (i.e. “Lep-dodendropsis” sp.), and are similar to those also recorded fromhe Do Son Formation. The Tan Lap Formation is an insert in theimestone of the Ban Pap Formation; its basal conglomerate restsnconformably upon Givetian limestone, and conformably on its

imestone containing an Early Frasnian Stachyodes costulata Assem-lage (Fig. 2) (Nguyen Huu Hung et al., 1991; Tong-Dzuy Thanh andu Khuc, 2006).

The Bang Ca Formation (D2 gv-D3 fr bc) is characterized mainlyy cherty shale, calcareous cherty shale and clay shale, and reaches

thickness of about 200–250 m. This formation occurs in the Haang area, West of the Cao Bang Province, and in the Dong Vannd Yen Minh areas of the Ha Giang Province, it is also exposedn the Van Yen area, Son La Province, in the West of Bac Bo. Theivetian age of the formation is based on the brachiopod Stringo-ephalus burtini, and by conodonts (Polygnathus xylus xylus, P. varcusnd P. linguiformis) collected in the Ban Cai area (West Bac Bo).he Frasnian age is based on foraminifera (Eonodosaria evlanen-is, Eogeinitziana aff. E. rara, Nanicella aff. N. uralica, and Tikhinellaultiformis) and conodonts of the Palmatolepis hassi and P. rhenana

ones (Pham Dinh Long, 2001; Ta Hoa Phuong, 1998).The Toc Tat Formation (D3fm-C1t tt) mainly consists of variegated

red-violet, brown-red, greenish-grey) limestone, cherty-clayhale and marl and argillaceous limestone. Calcareous cherty shalenterbeds are also frequent in the formation, especially on the


doi:10.1016/j.jog.2011.10.001

op of the sections. It is usually exposed in narrow bands, likehe uppermost part of the section in all the distribution areas ofhe Devonian. In the East of Bac Bo, the Toc Tat Formation occursn the Trung Khanh District (Cao Bang Province), where its shale


contains manganese ore, and in some areas there are importanteconomic seams. In the Dong Van Plateau (Ha Giang Province),and the West of Bac Bo, in the Van Yen area (Son La Province). Thetotal thickness of the formation varies from 260–280 m to 350 m.The fossils collected in the Toc Tat Formation comprise bivalves,brachiopods, foraminifera, and conodonts, most of them, especiallythe conodonts (Palmatolepis minuta, P. glabra, P. marginifera, P.gracilis, P. sigmoidalis), indicating a Famennian age. However, in theuppermost part of the formation occurs a Tournaisian fauna, withsuch conodonts as Siphonodella sinensis, S. duplicate, S. isosticha,and such foraminifera as Chernyshinella glomifomis, C. triangularis,C. uralica (Pham Dinh Long, 2001; Ta Hoa Phuong, 1998).

The Toc Tat Formation conformably rests upon the Bang Ca For-mation, and is covered unconformably by the Lower CarboniferousLung Nam Formation.

2.2.1.3. Western Bac Bo Zone. Except for the lower part of the LowerDevonian, the Western Bac Bo Zone shows Devonian units that aresimilar to those of Eastern Bac Bo Zone. In other words, from theupper part of the Lower Devonian, the lithology of the synchronousdeposits in two zones of the Bac Bo Region resembles each other.Actually, as described hereinbefore, the Ban Pap, Bang Ca, and TocTat Formations extend in both Eastern and Western zones of theBac Bo Region. Therefore, in this section about the Western Bac BoZone we only describe the Devonian Song Mua, Ban Nguon, andNam Pia Formations.

The Song Mua Formation (D1 sm) is distributed in the lower sec-tion of the Song Da River and is characteriztically very thick (from1500 m to 2300 m, depending on the areas), it mainly includes blackclay shale, and is thus clearly distinguished from other Devonianunits of Viet Nam (Nguyen Vinh, 1978; Tong-Dzuy Thanh and VuKhuc, 2006).

Based on its lithology and fauna, the Song Mua Formationcan be subdivided into three parts. The 600–1500 m thick lowerpart consists of black, black-grey, thin-bedded calcareous clayshale containing poorly preserved fossils. The 500 m thick middlepart is composed of grey to black marly shale containing bra-chiopods (Mesodouvillina aff. M. subinterstrialis, Iridistrophia aff. I.praeumbracula, Howellella sp., Schellwienella sp., Camarotoechia sp.,Platyorthis sp.) and bivalves (Pteria sp., Sphenotus? sp., Posidoniasp.). The 600 m thick upper part of the formation includes black,black-grey clay shale, and quartzitic sandstone containing numer-ous Howittia cf. wangi, Pugnacina sp., Lingula sp., Sphenotus? cf. S.spatulata, Mytilarca? sp., Pteria (Actinopteria) sp.). The Song MuaFormation rests conformably upon the Bo Hieng Formation, andconformably underlies the Ban Nguon Formation.

The Ban Nguon Formation (D1 bn) occurs in the lower section ofSong Da River basin, where it is exposed side by side with the under-lying Song Mua Formation. It is mainly composed of argillaceousshale, quartzitic sandstone, and limestone.

In its stratotype, the formation consists of argillaceous shale andquartzitic sandstone, and marly shale containing abundant bra-chiopods and bivalves. In the Hoa Binh-Tu Ly section, its thicknessreaches 750 m, and its carbonate components include corals andstromatoporoids. The fauna of the formation belongs to the PragianEuryspirifer tonkinensis Assemblage. Its characteriztic species arecorals (Favosites goldfussi, Squameofavosites attenuatus, Caliaporamacroporosa, Heliolites vulgaris, H. barrandei, Pseudozonophyllumaff. P. zmeinogorskiensis), stromatoporoids (Stromatoporella rara,Tienodictyon sp., Trupetostroma sp., Salairella sp., Clathrocoilona sp.)and brachiopods (Dicoelostrophia annamitica, Euryspirifer tonkinen-sis, Nervostrophia rzonsnickajae, etc.). The Ban Nguon Formation


rests conformably upon the Song Mua and beneath the Ban Papformation. By its stratigraphic relations and faunal composition,the Ban Nguon Fm. can be regarded as synchronous with the MiaLe Fm. of the Eastern Bac Bo Zone, but differs from the latter by

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ts lithological components (Nguyen Xuan Bao, 1978; Tong-Dzuyhanh and Vu Khuc, 2006).

The Nam Pia Formation (D1 np) is widespread in West Bac Bo,rom the upper course of the Da River (Lai Chau Province), followinghe eastern margin of the Song Ma Structure to the West and Eastf Thanh Hoa Province.

With a thickness of about 350 m, the Nam Pia Formation consistsf two parts. The lower part includes puddingstone, conglomeratend gritstone, and coarse-grained quartzite, with some interbedsf clay shale in the top. The upper part is composed of black-greylay shale interbedded with marl and quartzite, marl and lime-tone lenses in the top. Their faunas are distinguished by twossemblages corresponding to the two levels, respectively. Theormer one includes brachiopods belonging to the Iridistrophiaraeumbracula Assemblage of the lowermost level of the Devo-ian. The latter one contains corals and brachiopods belonging tohe Pragian Euryspirifer tonkinensis Assemblage. The most char-cteriztic of them are the corals Favosites brusnitzini, F. stellaris,. alpina, F. sublatus, F. ottiliae, Squameofavosites cechicus, S. bao-acensis, Emmonsia yenlacensis, Cladopora rectilineata, Lecomptiaamose, and the brachiopods Euryspirifer tonkinensis, Schellwienellaantenoisi, Dicoelostrophia annamitica, Nervostrophia rzonsniskajae,tc. The Nam Pia Formation rests in “pseudo-conformity” uponandstone of the Dong Son Formation (O1 ds) and conformablynderlies the Ban Pap Formation (Bui Phu My, 1978; Tong-Dzuyhanh and Vu Khuc, 2006).

The Ta Khoa Formation (D1 tk) is composed of two parts. Theower part consists of grey, thin-bedded sandstone and quartzitic


doi:10.1016/j.jog.2011.10.001

andstone intercalated with grey sericite schist and sericite-biotitechist, and the upper part consists of sericitized black schist. Bra-hiopods (Stropheodonta annamitica, Spirifer sp., Atrypa reticularis,rthis sp., Leptaena sp. indet., Chonetes sp. indet.) (Le Thac Xinh and

ig. 9. Correlation of the Devonian deposits in the Viet-Lao Region. (A) South of Binh Tri

c)—Red beds containing inarticulate brachiopods; 3. Tan Lam Formation (D2gv-C1 tl); 4.ormation (D1 rc); 2. Ban Giang Formation (D1-D2e bg); 3. Muc Bai Formation (D2gv mb); 4ormation (D3 xn). (C) Dien Bien-Nghe An Zone: 1. Ordovician-Silurian Song Ca Formation (an Formation (D2 gv-D3 nc).

PRESSynamics xxx (2011) xxx– xxx

Hoang Tri Nghi, 1964) and phacopid trilobites have been collectedat Ban Mong Village in dark schist belonging to the upper part of theformation (Phan Cu Tien et al., 1977). In addition, Nguyen Huu Hung(in Tong-Dzuy Thanh and Vu Khuc, 2006) has reported Howellellacf. H. crispa, Levenea cf. L. depressa, Fasculiptera sp., Howellella cf.H. crispa, Howellella sp., Dicoelostrophia sp., Atrypa sp., the bivalvesModiomorpha oblonga and Modiolopsis cf. M. wuxuanensis, the trilo-bites Ancanthopyge cf. A. yiminensis, the crinoids Hexacrinites (?)trangxaensis, Hexacrinites sp., and the bryozoan Fenestella sp.

The thickness of the Ta Khoa Formation is variously assessed:more than 3000 m, according to some geologists, or less than2000 m according to others. The contact of the Ta Khoa with theunderlying formation has never been observed, and its relation tothe overlying formation is either conformable according to somegeologists, or uncomformable to others. The fauna that has beencollected from the upper part of the Ta Khoa Formation correspondsto the Euryspirifer tonkinensis Assemblage, and can thus be corre-lated with the level of the Mia Le and Ban Nguon formations, ofPragian age.

2.2.2. Viet-Lao Region (Fig. 9)See Fig. 9.

2.2.2.1. Dien Bien-Nghe An Zone. The Huoi Loi Formation (D1-2 hl) isdistributed in some areas of the West of Nghe An Province, notablyin the Muong Xen area and as a slender wedge form in Cua Rao, andit can be divided into two parts.

The lower part is about 300 m thick and composed of light grey,


medium bedded sandstone, and upwards in the sequence are red-dish brown thin interbeds of sandstone and argillaceous shale.The latter yields Howellella sp., Stropheodonta sp., Hexacrinites?Humilicarinatus, Lissocrinus sp. The upper part consists of 200 m

Thien Zone: 1. Upper Silurian Dai Giang Formation (S3-4 dg); 2. A Choc Formation (D1

Phong Son Formation (D3-C1 ps). (B) North of the Binh Tri Thien Zone: 1. Rao Chan. Dong Tho Formation (D2 gv-D3 fr dt); 5. Thien Nhan Formation (D3 tn); 6. Xom NhaO3-S2 sc); 2. Tay Trang Formation (S3-D2e tt); 3. Huoi Loi Formation (D1-2 hl); 4. Nam

dx.doi.org/10.1016/j.jog.2011.10.001

https://www.researchgate.net/publication/292751527_Cau_tao_dia_chat_vung_Ta_Khoa_Geological_structure_of_the_Ta_Khoa_area?el=1_x_8&enrichId=rgreq-e809e99f168b313b450cad79320e6be1-XXX&enrichSource=Y292ZXJQYWdlOzI1OTEyMjkyODtBUzoyODg3OTUzMDQ5NzIyOTFAMTQ0NTg2NTU3NTA0Mw==

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hick sandstone interbedded with limestone lenses, and containsivalves (Glossites sp., Sphenotus sp., Archaeocardium sp.), stromato-oroids (Stromatopora concentrica, Amphipora ramose) and coralsThamnopora cf. T. polygonalis, Crassialveolites crassus, Temnophyl-um sp.).

The relation of the Huoi Loi Formation to the underlying for-ation is not observed, and it conformably underlies the Nam Can

ormation. The fauna from its lower part indicates a Late Emsiange, and that from its upper part suggests an Eifelian to Give-ian age. In sum, the Huoi Loi Formation can be referred to themsian–Givetian (Nguyen Van Hoanh, 1995).

The Thien Nhan Formation (D3 tn) occurs in a narrow NW-SErending band, extending from the northeast of Huong Son, theouthwest of Thanh Chuong, Nam Dan (Nghe An Province), Ducho to Ky Anh districts (Ha Tinh Province). With the thickness ofbout 800 m, it consists of dark grey siliceous shale and interbeds ofrgillaceous-siliceous shale, fine-grained sandstone, and siltstone.

Fossils are rare and poorly preserved, consisting of the con-donts Ozarkodina (Spathognathodus) sp. and Palmatolepis sp., ofate Devonian age, and entactiniid and albaillellid radiolarians thatndicate a Middle-Late Paleozoic age.

Similar deposits occur in the Tuyen Hoa and Minh Hoa Districts,Quang Binh Province), where black argillaceous shale, chert andiltstone, siliceous siltstone, and thin manganese interbeds, aresed to describe the Ngoc Lam Formation. Here were found theonodont Palmatolepis subrecta and the brachiopod Calvinaria cf.egistanu.

The lower and upper boundaries of the Thien Nhan Formationave not been observed, but the “Ngoc Lam Formation” con-

ormably rests between the underlying sandstone of the Dong Thoormation (D2 gv-D3fr dt), and the overlying banded limestone andhert of the Xom Nha Formation (D3 xn) (Tong-Dzuy Thanh and Vuhuc, 2006).

The Nam Can Formation (D2 gv-D3 nc) is restricted to the westerny Son District (Nghe An Province) in a narrow, 20 km long band,nd possibly extends into the Xieng Khoang Province of Laos. Itshickness reaches 600 m.

The Nam Can Formation comprises two parts. The lower part con-ists of grey, bedded limestone, siliceous limestone, thin interbedsr lenses of chert, containing Amphipora sp., Trachypora sp., Stachy-des radiata, Amphipora ramosa minor, and the corals Thamnoporaolyforata and Thamnophyllum sp. The upper part includes mainlyark grey limestone with many calcite veins, and interbedsf argillaceous shale, containing Stachyodes radiata, Amphiporaamosa minor, the corals Thamnopora polyforata and Thamnophyl-um sp., late Frasnian conodonts (Palmatolepis gigas, P. foliacea,. cf. P.triangularis, Ancyrognathus triangularis, Polygnathus xylus,pathognathodus sp.), and Famennian conodonts (Nothognathellap., Palmatolepis glabra glabra, P. perlobata schindewolfi, P. tra-hytera) (Le Duy Bach and Nguyen Van Hoanh, 1995).

The Nam Can Formation has conformable relations to the under-ying Huoi Loi Formation. Its upper boundary usually shows aectonic contact, but seems to be conformable with the overlyingower Carboniferous chert.

.2.2.2. Binh Tri Thien Zone. The A Choc Formation (D1 ac) shows aestricted distribution in Quang Tri Province, crops out from A Choco Ta Puong villages (Huong Hoa District), and in Tan Lam area it isxposed along the Road № 9. It was termed Tan Lam Formation inormer Vietnamese publications (Dang Tran Huyen et al., 1980), buthe name Tan Lam was used earlier by Tran Thi Chi Thuan and H.ontaine (1968) for the Devonian Tan Lam Limestone (Calcaire de


doi:10.1016/j.jog.2011.10.001

an Lam) distributed in the same Tan Lam area (Quang Tri Province).he formation is composed of sandstone and siltstone interbeddedith some argillaceous shale of chocolate colour, and its thick-ess does not exceed 100 m. The lowest beds consist of sandstone,


conglomerate and pebble-bearing sandstone, with 3–5 cm large,more or less rounded pebbles made of quartz, quartzite, sand-stone, siltstone, chert and sericite schist. The Early Devonian ageof the formation is suggested by inarticulate brachiopods Lingulaaff. L. loulaensis, L. cf. muongthensis, L. cf. L. cornea, L. aff. L. hawkei,Lingula sp. The A Choc Formation rests unconformably upon the Sil-urian Dai Giang Formation, but its upper boundary is still unknown(Tong-Dzuy Thanh and Vu Khuc, 2006).

The Rao Chan Formation (D1 rc) is characterized by black shale,calcareous shale and sandstone, and limestone lenses, which arewidespread in the West of Quang Binh and Ha Tinh Provinces. Thethickness of the formation reaches more than 2000 m.

The corals that have been collected in the limestone of the lowerpart of the formation include Pachyfavosites cf. P. delicatus, Alve-olites sp., Coenites cf. simakovi, Heliolites cf. H. insolens, Chaetetesninae. Desmidopora? sp., Dohmophyllum sp. The upper part of theformation yields brachiopods (Desquamatia vijaica, Levenea aff. L.transversa) and the crinoid Lissocrinus curtus. The Rao Chan For-mation is referred to the Lower Devonian; it pseudoconformablyoverlies the Dai Giang Formation (S3-4 dg), and conformably under-lies the Ban Giang Formation (D1-D2e bg) (Tran Tinh, 1996).

The Ban Giang Formation (D1-D2e bg) is about 700 m thick andcrops out in the West of Quang Binh and Ha Tinh Provinces. It con-sists of sandstone, quartzitic sandstone, siltstone interbeds, andsome calcareous argillaceous shale, limestone lenses in its upperpart.

The fauna it yields comprises species ranging from the LowerDevonian (Emsian) to the Middle Devonian. Emsian species fromthe lower part of the formation include corals (Calceola sandalina,Stringophyllum sp.), crinoids Hexacrinites biconcavus, H. humilicari-natus), brachiopods (Atrypa auriculata, Chonetes sp.), and trilobitesDechenella (Basidechenella?) sp. The limestone of the upper partof the formation yields Middle Devonian species, such as corals(Gephuropora vietnamica, Thamnopora nicholsoni, Cladopora gracilis,Crassialveolites cf. C. multiperforatus, Thamnophyllum khelopense,Pseudogrypophyllum stenotabulatum, Heliolites pororus, Parahelio-lites cf. P. hanusi) and strmatoporoids (e.g., Stromatopora hupschii).The Ban Giang Formation conformably rests between the under-lying Rao Chan Formation (D1 rc) and the overlying Muc BaiFormation (D2gv mb) (Tong-Dzuy Thanh and Vu Khuc, 2006).

The Muc Bai Formation (D2gv mb) occurs mainly in NW–SE bandsin the west of Ha Tinh and Quang Binh Provinces and consistsof terrigenous-carbonate deposits containing an abundant benthicfauna. With the thickness of about 800 m, the sequence of this for-mation is characterized by the intercalation of marly limestone,calcareous shale, sandstone, siltstone, argillaceous shale, in whichthe fauna is usually met with in calcareous host rocks. The con-formable relation of the Muc Bai Formation with the underlyingBan Giang Formation and the overlying Dong Tho Formation is wellobserved.

Among the abundant fossils from the Muc Bai Formation,the most characteriztic ones indicate a Givetian age, such asthe brachiopods (e.g., Stringocephalus burtini, Bornhardtina sp.,Schizophoria striatula, Gypidula biplicata, Emanuella takwanensis)and the corals (Thamnopora nicholsoni, Caliapora battersbyi, Scol-iopora denticulata, Iowaphyllum chucaense, Dendrostella trigemme).In addition, the formation yields numerous stromatoporoids (e.g.,Amphipora ramosa minor, Amphipora minima, Hermatoporella poro-sum, Flexiostroma flexiosum, Stachyodes concent, Clathrostromaactinostromoides) (Tran Tinh, 1996; Tong-Dzuy Thanh and Vu Khuc,2006).

The Dong Tho Formation (D2 gv-D3 fr dt) is characterized by


coarse sediments with a thickness of about 400 m and clearlydivided into two parts (Dovjikov et al., 1965). The lower part (150 mthick) consists of dark grey argillaceous shale, sometimes withinterbeds of marly shale and sandstone, and the upper part (250 m

dx.doi.org/10.1016/j.jog.2011.10.001

https://www.researchgate.net/publication/292755694_Note_sur_la_province_de_Quang_Tri_et_description_de_quelques_brachiopodes?el=1_x_8&enrichId=rgreq-e809e99f168b313b450cad79320e6be1-XXX&enrichSource=Y292ZXJQYWdlOzI1OTEyMjkyODtBUzoyODg3OTUzMDQ5NzIyOTFAMTQ0NTg2NTU3NTA0Mw==




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hick) is composed of light grey, yellowish grey sandstone, some-imes with shale interbeds. The Dong Tho Formation conformablyverlies the Muc Bai Formation (D2gv mb), and conformably under-ies the “Ngoc Lam Formation”, the latter being an equivalent ofhe Thien Nhan Formation (D3 tn) (Tong-Dzuy Thanh and Vu Khuc,006).

The Dong Tho Formation yields brachiopods (Atrypa reticu-aris, Spinulicosta spinulicosta, Stropheodonta sp., Megachonetes sp.,chizophoria cf. S. ivanovi, Adolfia sp.) and bryozoans Fenestella sp.)n the Hoi Da Stream, near Minh Le Village, an abundant flora haseen found in the siltstone and shale. The macrofossils have beeneferred to Lepidodendropsis sp. and Protolepidodendron sp., andhe sporomorphs to e.g., Apiculatisporites sp., Gymbosporites mag-ifica, Costazonotriletes latidentatus, Archaezonotriletes variabilis,


doi:10.1016/j.jog.2011.10.001

holisporites densus, Aneurospora goensis, Ancyrospora involucra,nd A. tenicaulis. From the sandstone of the Ly Hoa Pass there areertebrates Lyhoalepis duckhoai, and Vukhuclepis lyhoaensis (Tong-zuy Thanh et al., 1994, 1997).

per Devonian Xom Nha Formation.

The Xom Nha Formation (D3 xn) is about 200 m thick, and char-acterized by dark grey, light grey stylolitic limestone containingabundant corals, stromatoporoids and conodonts, and it crops outin the West of Quang Binh Province, as well as in the Chuc A area,Ha Tinh Province (Fig. 10).

The lower part of the formation contains Frasnian fossils, suchas stromatoporoids (Stachyodes costulata, S. angulata, S. parallelo-poroides; corals Scoliopora denticulata, Thamnopora polyforata,Temnophyllum isetense) and the conodont Palmatolepis gigas.Fossils from the upper part include Famennian conodonts of thePalmatolepis triangularis, P. marginifera and P. crepida Zones. TheXom Nha Formation conformably rests upon the cherty shale andcarbonaceous shale of the “Ngoc Lam Formation” (= Thien NhanFormation-D3 tn), and shows an unconformity with the overlying


Lower Carboniferous La Khe Formation (Nguyen Huu Hung et al.,1995).

The Tan Lam Formation (D2gv-C1 tl) was termed Cu Bai For-mation in former Vietnamese publications (Nguyen Xuan Duong,

dx.doi.org/10.1016/j.jog.2011.10.001

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996), but the name Tan Lam Limestone was used earlier by Tranhi Chi Thuan and H. Fontaine (1968) for this limestone. The forma-ion consists mainly of black-grey limestone, light-grey dolomiticimestone occurring sporadically in the West of Quang Tri Province,nd in the Le Thuy, Phong Nha areas of Quang Binh Province.he fauna collected from the Tan Lam, Cu Bai, and A Choc sec-ions (Quang Tri Province) suggests for this formation has an agehat ranges from the Givetian to the Famennian. In the lowerart of the formation, it includes Givetian stromatoporoids (e.g.,mphipora ramosa, A. pinguis) and corals (Dendrostella trigemme,rgutastrea lavali, Disphyllum sp.). The middle part of the formationields Frasnian foraminifera (Tournayella jubra, Eonodosaria sp.),tromatoporoids (Stachyodes costulata, Amphipora laxeperforata),nd brachiopods (Uchtospirifer nalivkini). Famennian brachiopodsTenticospirifrer minor, Cyrtospirifer postarchiaci, Cyrtiopsis graciosa,chtospirifer nalivkini, Yunnanellina sp.) occur in the upper part of

he formation (Tong-Dzuy Thanh and Vu Khuc, 2006).The Le Thuy and Phong Nha areas (Quang Binh Province)

imestone, possibly belonging to the uppermost Tan Lam For-ation, contains Famennian-Lower Carboniferous fossils, such

s foraminifera (e.g., Eoendothyra communis, Quasiendothyraobeitusana, Tournayella jubra, Parathurammina suleimanovi, Sep-atournayella pseudocamerata), the coral Pseudouralinia aff. P.angpakonensis and the brachiopod Crurithyris urii.

The thickness of the formation in Tan Lam area is about 150 m,nd the limestone corresponding to its uppermost part in Le Thuynd Phong Nha areas reaches about 170–300 m, so the total thick-ess of the Tan Lam Formation reaches 500 m and more. Thean Lam Formation rests unconformably upon the Dai Giang For-ation (S3-4 dg), the upper boundary of the formation is not

lear.The Phong Son Formation (D3-C1 ps) occurs only in Thua Thien

Hue Province), with few natural exposures, but drilling informa-ion shows that it extends in NW-SE trending bands from the southf Hue City. The formation consists of ash and dark grey limestoneegularly intercalated with black clay shale containing fossils ofamennian age in its lower part and Lower Carboniferous onesn its upper part. Famennian fossils from the lower part compriserachiopods (e.g., Yunnanella hsikwangshaensis, Yunnanellina cf. Y.anburyi, Uchtospirifer sp., Athyris concentrica, Tenticospirifer tentic-lum). The upper part yields a Late Famennian–Early Carboniferousauna, with such foraminifera as Septabrunsiina cf. minuta, S. cf. S.auserae, Septabrunsiina cf. S. kazakhtanica, Septatournayella cf. S.egmentata, or Chernyshnella sp., and the corals Syringopora sp. andseudouralinia sp. (Tong-Dzuy Thanh and Vu Khuc, 2006).

.2.3. South Viet Nam Region

.2.3.1. South Trung Bo Zone (southern part of Viet Nam Central).he Cu Brei Formation (D1 cb) consists of 400 m thick terrigenous-arbonate sediments, distributed only in a narrow (6 km long, 3 kmide) strip in the Cu Brei Mountain area (Yaly Commune, Sa Thayistrict of Kon Tum Province), i.e. in the western margin of the Konum Block.

The formation is divided into two parts: the lower part con-ists of conglomerate, gritstone and sandstone, argillaceous shale,ome argillaceous schist interbeds, the upper—green grey talc schist,imestone, dolomitised limestone, marly shale containing the coralquameofavosites aff. S. spongiosus, stromatoporoids (Syringostromaf. S. densum, Amphipora cf. A. raris, A. cf. A. raritalis, Simplexo-ictyon cf. S. artyschtence, Stromatopora cf. S. boriarchinovi), andther undeterminable algae and crinoids. The Cu Brei Formation


doi:10.1016/j.jog.2011.10.001

ests unconformably on the biotite-hornblende granitoid Dien Binh384 ± 17; 418 ± 12 Ma by K/Ar method), and the mentioned coral,tromatoporoid assemblage indicates the Early Devonian age of theormation (Tong-Dzuy Thanh et al., 2007).


2.2.3.2. Western Nam Bo Zone. The Hon Heo Formation (D? hh)mainly consists of sandstone, clay shale, occurring scatteredly inthe Kien Giang Province, in coastal areas and in some islands of theGulf of Thailand, such as Hon Trem, Hon Chong, Hon Heo, Bai Ot,Hon Mot, Ba Lua Islands, etc. Fossils are rare and represented bypooly preserved plant remains referred to, e.g., Taeniocrada? sp.,Psilophyton sp. (Tong-Dzuy Thanh and Vu Khuc, 2006).

Since the formation is scattered over the islands, its stratigraphicrelations to the adjacent formations are unknown. The Hon HeoFormation is supposedly referred to the Devonian on the basis ofthe mentioned plant remains, but the study of Paleozoic spores inViet Nam is inadequate, so the age of this formation is still a matterof controversy.

3. Facies distribution

3.1. Facies of the Silurian deposits

Silurian deposits in Viet Nam are differentiated into deep-waterfacies containing graptolites and shallow water shelf facies. Thedeep-water facies are characterized for the upper parts of theOrdovician-Silurian formations, for instance, Co To and Tan Maiformations in the Quang Ninh Zone, Phu Ngu Formation in the EastBac Bo Zone, and Long Dai Formation in the Binh Tri Thien Zone,Song Ca Formation, and the lower part of the Tay Trang Formationin the Viet-Lao Region. The shallow water shelf facies is widespreadfor most Silurian formations, such as the Kien An Formation in theQuang Ninh Zone, the Sinh Vinh and Bo Hieng Formations in theWest Bac Bo Zone, and the Dai Giang Formation in the Binh TriThien Zone.

3.1.1. Deep water facies of Lower Silurian deposits in the Bac BoRegion (Fig. 11)

In the Quang Ninh Zone, both the Co To and Tan Mai Forma-tions have been dated as Ordovician-Silurian, but fossils collectedin their upper parts indicate the Early Silurian only. The deep-waterfacies of these formations have been proved by their fine-grainedcomponents, rhythmic structure in its sequence, and by graptolitesassemblages, such as Streptograptus exiguus, Monograptus priodon,Spirograptus cf. minor, Oktavites aff. O. planus, Campograptus com-munis, Demirastrites sp., Climacograptus sp., Monograptus ex gr.pandus, Pristiograptus cyphus, Pseudoclimacograptus sp., Demiras-trites triangularis, and Monoclimacis linarsoni (Nguyen Cong Luong,2001a,b).

In the Co To Formation, the sections are turbidite-like andbelong to a dissected island arc environment (Pham Thanh Binhand Nguyen Cong Luong, 1999). The studies by Nguyen Xuan Khien(2000) have shown that the clastic components of the Co To Forma-tion were deposited in a forearc sedimentary basin, and originatedfrom a regenerated orogenic process. The Tan Mai Formation, alsoshows tuffaceous materials and rhythmic structure in its sequence,but these are different from those observed in the Co To Formation,the fragments of felsic effusive being absent in the componentsof sediments, and fine-grained rocks being less abundant than inthe Co To Formation. Thus, perhaps the Tan Mai formation wasattributed to the back-arc marine basin situated near an old con-tinental margin (Nguyen Xuan Khien, 2000; Tong-Dzuy Thanh andVu Khuc, 2006).

In the East Bac Bo Zone, the Phu Ngu Formation reachesa thickness of more than 2000 m, consisting of argillaceousshale, cherty-argillaceous shale rhythmically interbedded withsilty sandstone, and felsic effusive. The formation was dated


as Ordovician-Silurian, but fossils from the sections indicate anOrdovician-Early Silurian age. Most of these fossils are graptolitessuch as Climacograptus sp., Glyptograptus sp., Monoclimacis sp., andDiplograptus sp., Climacograptus latus, Climacograptus cf. C. scolaris,

dx.doi.org/10.1016/j.jog.2011.10.001




vonia

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tilograptus sp., Glyptograptus sp., and the trilobite Agnostus per-ugatus. All these lithological and faunal characteriztics indicate aeep-water facies of the deposits in an island arc environment inhe sedimentary process of the Phu Ngu Formation (Pham Dinhong, 2002; Tong-Dzuy Thanh and Vu Khuc, 2006).

.1.2. Deep water facies of Silurian deposits the Viet-Lao RegionFig. 12)

In the Dien Bien-Nghe An Zone, the deep-water facies of theilurian deposits are expressed in the the upper part of therdovician-Silurian Song Ca Formation and perhaps in the lowerart of the Upper Silurian-Eifelian Tay Trang Formation.

The deep-water facies of the Song Ca Formation are evidencedy its fine-grained deposits reaching more than 2000 m in thick-ess, and containing Early Silurian graptolites in the upper part,uch as Monoclimacis vomerinus and Pristiograptus kweichihensis.he deep-water facies are also characterized for the lower part ofhe Silurian-Eifelian Tay Trang Formation, which consists of thin-edded siltstone, dark grey clay shale, and fine -grained sandstoneontaining the graptolites Bohemograptus bohemicus, M. thomasi,nd M. yukonensis. Thus, in the Dien Bien-Nghe An Zone the deep-ater facies characterizing all Silurian deposits includes the Lower

ilurian of the upper part of the Song Ca Formation and the Upperilurian in the lower part of the Tay Trang Formation.


doi:10.1016/j.jog.2011.10.001

Incidentally, it is worth noting that the Lower Silurian Ketay Formation (Le Thanh Huu and Vu Xuan Luc, 2005), dis-

ributed along the northeast side of the Song Ma structure of theresent limits of the West Bac Bo Zone, is also characterized by

n deposits of the Bac Bo Region in the present situation.

deep-water facies. Originally, this formation was a Silurian com-ponent of the Song Ca Formation in the Dien Bien-Nghe An Zone,but was displaced to the northeast edge of the Song Ma structureand wedged into the bodies of the Neoproterozoic Nam Co For-mation by an imbricate fault (personal communication from Prof.Tran Van Tri).

In the Binh Tri Thien Zone, the deep-water facies is composedof the upper part of the Ordovician-Lower Silurian Long Dai For-mation, which consists of black argillaceous shale, clay-chloriteshale with some interbeds of tuffaceous sandstone, and gritstonecontaining Silurian graptolites Neodiversograptus nilssoni, Pris-tiograptus sp., Demirastrites convolutus, Monograptus halli, Oktavitesspiralis, Bohemograptus bohemicus, and Monoclimacis sp. (NguyenXuan Duong, 1996).

In summary, the deep-water facies is observed in Lower Silurianin the Quang Ninh and East Bac Bo Zones, where some tuffaceoussediments or effusive beds are interbedded in the sequences andpossibly indicate the arc basin of the sedimentary environment. Inthe Viet-Lao Region, the deep-water facies is characteriztic for allSilurian deposits of the Dien Bien-Nghe An Zone, and the LowerSilurian only in the Binh Tri Thien Zone. In the West Bac Bo Zonethere is no Silurian deep-water facies, all Silurian deposits in thiszone are characterized by shallow water facies.


3.1.3. Shallow water facies of the Silurian deposits in the Bac BoRegion (Fig. 11)

In the Quang Ninh Zone, the shallow water facies of the UpperSilurian includes the Kien An Formation, which occurs in a small

dx.doi.org/10.1016/j.jog.2011.10.001

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rea near Hai Phong City. Silty sandstone, marly shale, and lime-tone containing abundant benthos fauna of the formation suchs corals and brachiopods indicate the shallow water facies of theeposits. Among the recorded fossils the brachiopods of the Ret-iella weberi Assemblage play an important role; its components,specially the index species, are widespread in Upper Silurian ofsia and Australia (Tong-Dzuy Thanh et al., 2001).

In the West Bac Bo Zone, all Silurian deposits (upper part of theinh Vinh Formation, and the Bo Hieng Formation) are composedf carbonate deposits containing an abundant benthic fauna. Thepper part of the Sinh Vinh Formation consists of dolomitic lime-tone and limestone containing Late Silurian corals, e.g. Favositesp., F. aff. F. forsbesi, F. ex gr. gothlandica, F. cf. F. hisinger, F. cf. F.oreaniformis, Mesofavosites sp., Squameofavosites sp., and Parastri-topora sp. The Upper Silurian Bo Hieng Formation consists of marlyhale, limestone and some banded argillaceous shale containingorals, brachiopods, and bivalves. Among the corals there are alsoabulates, such as Palaeofavosites aff. P. balticus, Favosites kernihoen-is, and the rugosan Aphyllum aff. A. sociale. Remarkable fossils inhis formation are representatives of the Retziella weberi Assem-lage, and bivalves Modiomorpha brevis, M. sp., Cymatonota sp. (aff.. yunnanensis), Dysodonta sp., and Actinopteria sp. (Ta Hoa Phuongnd Le Van Manh, 1996; Tong-Dzuy Thanh and Vu Khuc, 2006).hus, carbonate sediments and abundant benthic fauna clearlyndicate the shallow water shelf facies of the Silurian deposits inhe West Bac Bo Zone.

In the East Bac Bo Zone, the Upper Silurian is either lacking orailed to be identified in the sections, and the Lower Devonian Rededs unconformably overly the older Silurian deposits.

.1.4. Shallow water facies of Silurian deposits in the the Viet-Laoegion (Fig. 12)

In the Viet-Lao Region, the shallow water facies is characterizticor Upper Silurian deposits in the Binh Tri Thien Zone (Dai Giangormation), but this facies is lacking in the Silurian of the Dien Bien-ghe An Zone (Fig. 12).

The Dai Giang Formation (S3-4 dg) consists of gritstone andoarse-grained sandstone at its base, which unconformably over-ies the Long Dai Formation. The main composition of the formationonsists of terrigenous deposits, such as sandstone, and lime-tone, marl beds in its upper part. Its benthic fauna includerilobites (Cromus beaumonti, Metacalymene sp., Praedechenella aff.. vietnamica, Encrinurus cf. E. sinicus), brachiopods of the Retziellaeberi Assemblage, and bivalves (Schizodus? myducensis, Sphenotus

ntecedens, Modiomorpha paracrypta, Goniophora dianensi) (Nguyenuan Duong, 1996). In addition the Dai Giang Formation yieldedlacoderm (Myducosteus anmaensis) and acanthodian fish remainsTong-Dzuy Thanh et al., 1997; Janvier and Tong-Dzuy Thanh,998). The composition of the sediments and the benthic fauna

ndicates that the Dai Giang Formation corresponds to a shallowater facies deposited in a littoral environment.

.2. Facies of the Devonian deposits

Deep-water facies in the Devonian deposits of Viet Nam arearely observed, and most Devonian units belong to different kindsf shallow water facies.

.2.1. Lower DevonianThe lowermost Devonian sections are distributed into two kinds.

he first one is represented by the sections that are continuous sincehe Upper Silurian, and the second one by the Devonian sections


doi:10.1016/j.jog.2011.10.001

hat are separated from older deposits by an unconformity.In the areas where the sections are continuous since the Upper Sil-

rian, there is no sudden vertical change in the facies of deposition.n the west Bac Bo Zone, the Lower Devonian Song Mua Formation


conformably overlies the Upper Silurian Bo Hieng Formation. Boththe Bo Hieng and Song Mua formations belong to the shallow waterfacies, although their sedimentary components differ. The formerconsists of carbonate-terrigenous deposits that yield a benthicfauna and belongs to the shallow water shelf facies. The latter, thethick Song Mua Formation, includes shale and sandstone bearingbrachiopods in the upper part, and showing possible shallow waterfacies of offshore environment. Other Silurian-Devonian continu-ous sections have been recorded in the Tay Trang Formation in theDien Bien-Nghe An Zone of the Viet-Lao Region. The lower partof this formation consists of thin-bedded siltstone, clay shale, andfine- to middle-grained sandstone containing deep-water UpperSilurian fossils, such as graptolites (Bohemograptus bohemicus, M.thomasi, M. yukonensis), and the dacryoconarids Nowakia cancel-lata and N. holynensis. The upper part of the formation mainlyconsists of siltstone, and sandstone containing Lower Devonianbrachiopods and cephalopods that indicate a shallow waterfacies.

Lower Devonian “Red Beds”: The lowermost part of the LowerDevonian in the East Bac Bo Zone of the Bac Bo Region and in theBinh Tri Thien Zone of the Viet-Lao Region begins by “Red Beds”,which unconformably overly the older sediments.

In the Western areas of the East Bac Bo Zone (Fig. 11), the Si KaFormation consists of conglomerate, greenish siltstone, clay shale,and marly shale, and chocolate marly shale containing vertebrateremains (Hoang Xuan Tinh, 2001). Upwards, the lower part of theBac Bun Formation consists of grey, chocolate, variegated weath-ering clay shale and marly shale, siltstone containing abundantremains of vertebrates (see above, in the description of the Si Kaand Bac Bun Formations). The upper part of the Bac Bun Formationconsists of shale, marly shale and limestone containing abundantshallow water benthos of the Howittia wangi Assemblage, suchas Howittia wangi, Cyrtochonetes indosinensis, Parachonetes zeili(Racheboeuf and Tong-Dzuy Thanh, 2000). The lithological com-position and fauna of the Si Ka and Bac Bun Formations (Song CauGroup) show that they probably belong to a transitional environ-ment, ranging from lagoonal, coastal and deltaic facies to onshoreshallow marine facies.

It is noteworthy that in a small area, northwestward of the EastBac Bo Zone, where the Khao Loc Formation (D1-2 kl) extended,the lower Devonian is distinguished from sections of the Song CauFormation described above. There, the “Red Beds” are absent, andthe lower parts of the Khao Loc Formation include marl and marlyshale containing vertebrates that can be correlated with thoseof the lowermost beds of the Devonian of Yunnan (China), suchas Youngolepis praecursor, Polybranchiaspis liaojaoshanensis, Mini-crania lissa, Laxaspis yulongsus, and Heteroyunnanolepis qujingensis(Tong-Dzuy Thanh et al., 1995; Janvier and Ta Hoa Phuong, 1999).

Lower Devonian “Red Beds” are also present in the south of theBinh Tri Thien Zone (Viet-Lao Region), which unconformably overlythe Upper Silurian Dai Giang Formation. Here, the A Choc Forma-tion consists of gritstone, conglomerate and sandstone, siltstone ofchocolate colour containing brachiopods (Lingula aff. L. loulaensis,L. cf. L. muongthensis, L. cf. L. cornea, L. aff. L. hawkei, Lingula sp). Thelithology and faunal composition suggests that the A Choc Forma-tion was deposited in a continental or brackish water environment(Tong-Dzuy Thanh and Vu Khuc, 2006).

3.2.2. Lower Devonian-Eifelian shallow water marine faciesFrom the upper Lower Devonian to the Eifelian most of Viet Nam


zones, such as the Red River uplift and the Kontum Block. Terrige-nous deposits extend on the territory of the Quang Ninh and BinhTri Thien Zones, whereas terrigenous-carbonates and carbonatesoccur in the other zones (Fig. 11).

dx.doi.org/10.1016/j.jog.2011.10.001






onian

3QetAraartabcac

3wbBc

etafAs

Fig. 12. Sketch of the facial profile of the Silurian and Dev

.2.2.1. Terrigenous deposits of shallow water marine facies.. In theuang Ninh Zone (Fig. 11), the Duong Dong Formation (D1-D2

dd) includes mudstone, fine-grained quarzitic sandstone con-aining, e.g., brachiopods, bivalves of the Euryspirifer tonkinensisssemblage. In the Binh Tri Thien Zone, both the Rao Chan (D1c) and Ban Giang (D1-D2e bg) formations mainly consist of shalend sandstone, carbonate components present in thin calcareousrgillaceous shale interbeds or limestone lenses only. All the fossilsecorded are benthic. For instance, those from the Rao Chan Forma-ion are corals (Pachyfavosites cf. P. delicatus, Coenites cf. C. simakovi,nd Heliolites cf. H. insolens, Chaetetes ninae. Dohmophyllum sp.),rachiopods (Desquamatia vijaica, Levenea aff. L. transversa) and therinoid Lissocrinus curtus. The fossils from the Ban Giang Formationre more diverse, with brachiopods, trilobites, crinoids, and someorals in the thin limestone lense.

.2.2.2. Terrigenous-carbonate and carbonate deposits of shallowater marine facies. Starting from the upper Lower Devonian, car-onate components predominate in the Devonian sections in theac Bo Region, and are increasing upwardly, becoming the mainomponent of the Eifelian sections in most zones.

Devonian carbonate components appear earliest in the north-astern area of the East Bac Bo Zone, from the lowermost beds ofhe Lower Devonian in the Khao Loc Formation, which in marly


doi:10.1016/j.jog.2011.10.001

rgillaceous shale yield vertebrate remains (see above). Upwards,rom the Givetian level with corals of the Euryspirifer tonkinensisssemblage, the Khao Loc Formation only consists of carbonateediments.

deposits of the Viet-Lao Region in the present situation.

The terrigenous-carbonate facies are widespread in upperLower Devonian of the Bac Bo Region, in the Mia Le Formation ofEast Bac Bo, and the Ban Nguon and Nam Pia formations of WestBac Bo (Fig. 11). The faunas are abundant, and there are more than300 species of corals, brachiopods, bivalves, trilobites, and crinoidsbelonging to the Euryspirifer tonkinensis Assemblage. This faunalcommunity is the most abundant and diversified among the Devo-nian faunas in the Bac Bo Region and in Viet Nam as a whole.Judging from the lithological composition and faunal assemblage,the upper Lower Devonian terrigenous-carbonate deposits in theEast Bac Bo, and West Bac Bo Zones were probably deposited in ashallow marine shelf environment.

3.2.2.3. Middle Devonian carbonate facies. The Middle Devoniancarbonate deposits occur in almost all zones of the Bac Bo andViet-Lao Regions. In the East Bac Bo and West Bac Bo Zones, theycompose the Eifelian-Givetian parts of the Ban Pap Formation andthe Khao Loc Formation, containing an abundant fauna of, e.g., stro-matoporoids, corals, and some brachiopods. The same also occursin the North of the Viet-Lao Region, i.e. in the Dien Bien-Nghe AnZone, where limestone is the main component of the Huoi Loi andNam Can Formations, but here some terrigenous composition alsooccurs as thin interbeds. Limestone appears later as the uniquecomponent, in the Givetian of the Quang Ninh Zone (Trang KenhFormation) and in the Binh Tri Thien Zone, in the Tan Lam Forma-


tion. Further northward in this zone, limestone appears even later,in the upper Givetian, as in the Muc Bai Formation (Fig. 12).

The faunal community in the Eifelian formations mainlyincludes corals, such as, e.g., Favosites styriacus, F. stellaris, F.

dx.doi.org/10.1016/j.jog.2011.10.001

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egularissimus, Emmonsia yenlacensis, Squameofavosites bohemicus,. enormis, and S. vanchieni. The dominant taxa in the Givetianollections are the representatives of the Caliapora batersbyissemblage, such as, e.g., Amphipora ramosa, Actinostroma clatra-

um, Thamnopora polygonalis, T. nicholsoni, Caliapora battersbyi,coliopora denticulata, and Dendrostella trigemme, and the brachio-od Stringocephalus burtini. The carbonate composition and coralauna demonstrate that the Devonian carbonate deposits in theac Bo and Viet-Lao Region represent a shallow water shelf facies.

Exceptionally, in small areas of Dong Van (Ha Giang Province)re limestone, clayey limestone, marl, black shale and chertnterbeds, containing an abundant pelagic fauna. In the lower bedsre Lower Devonian fossils of the Nowakia acuaria and N. barran-ei zones, conodonts of the Polygnathus excavatus, Pandorinellinateinhornensis, and Polygnathus. nothoperbonus zones, and still theorals Favosites regularissimus and Heliolites sp. In the upper beds,ivetian species have been found, such as, e.g., Palmatolepis var-us and others. The carbonate and siliceous composition and theelagic fauna suggests that the “Si Phai Member” of the Ban Papormation was deposited in an environment corresponding to thelope of the continental shelf.

Specific case of the Do Son and Tan Lap Formations (Fig. 11): The Doon Formation mainly consists of conglomerate at its base, cross-edded sandstone, and shale interbeds that occur in the Quang Ninhone. The Tan Lap Formation is composed of conglomerate, arkosicritstone, and arkosic sandstone interbedded with black siltstonehat extend in small areas of the East Bac Bo Region (Bac Son area).oth the Do Son and Tan Lap formations contain continental plantemains (Lepidodendropsis), and in the Do Son Formation there stillre bivalves, and vertebrates Vietnamaspis trii, Briagalepis sp., Aster-lepis sp. (Janvier et al., 1989; Long et al., 1990; Nguyen Huu Hungt al., 1991, 2007; Janvier and Tong-Dzuy Thanh, 1998). The litho-ogical composition and fauna indicate the continental and deltaicacies of the Do Son and Tan Lap formations. Both the Do Son andan Lap formations unconformably overly the older deposits, theo Son Formation upon the Eifelian deposits of the Duong Dongormation, and the Tan Lap Formation upon the Givetian limestonef the Ban Pap Formation. These coarse sediments of the Tan Lapnd Do Son formations can be regarded as transgression molasseseposited after a local elevation; a similar situation occurred inouth China (personal communication from Hou Hong-fei to Tong-zuy Thanh).

The case of the adjoining Muc Bai and Dong Tho FormationsFig. 12): The Muc Bai and Dong Tho Formations contiguouslyxtend in the the Binh Tri Thien Zone, the former mainly consist-ng of carbonate deposits, and the latter of coarse sandstone andrgillaceous shale. Both formations contain a benthic fauna, but inhe Muc Bai Formation, apart from brachiopods, there is a largeumber of coral colonies, while in the Dong Tho Formation there isnly a shelly fauna (brachiopods, bryozoans, etc.) and plant remainsLepidodendropsis sp., Protolepidodendron sp.) in some siltstone andhale interbeds. One can therefore suggest that these formationsere deposited in a shallow water environment of the same basin,

he Dong Tho Formation representing a coastal facies, and the Mucai Formation the onshore, shelf shallow water facies.

.2.3. Facies of the Upper Devonian depositsIn the Upper Devonian, the shelf shallow water facies are char-

cterized by a large number of carbonate formations in the Bac Bond Viet-Lao regions. In the Quang Ninh Zone (Figs. 11 and 12),ne can notice the upper part of the Trang Kenh Formation, in the


doi:10.1016/j.jog.2011.10.001

orth of the Dien Bien-Nghe An Zone, the upper part of the Naman Formation, and in the Binh Tri Thien Zone, the upper part of thean Lam and Phong Son formations. At the same time, there appeararbonate-siliceous deposits containing conodonts which indicate


a deep-water facies in some areas of both the Bac Bo and Viet-LaoRegions.

The deep-water facies in the Bac Bo Region begin with theGivetian-Frasnian Bang Ca Formation, which consists of chertyshale, calcareous cherty shale clay shale, occurring in the Ha Langarea of the East Bac Bo Region and in the lower section of the DaRiver basin. The fauna consists of conodonts of the Palmatolepishassi and P. rhenana Zones, and Polygnathus xylus xylus, P. varcus, P.linguiformis, and also the brachiopod Stringocephalus burtini.

The Toc Tat Formation (D3fm-C1t tt) that overlies the BangCa Formation is also characterized by deep-water facies, which isevidenced by its composition, consisting of variegated limestone,cherty-clay shale, marl, argillaceous limestone, and frequent cal-careous cherty shale interbeds. Fossils of this formation mainlyinclude conodonts, such as Palmatolepis minuta, P. glabra, P.marginifera, P. gracilis, and P. sigmoidalis, but there are also bivalves,brachiopods, and foraminifera.

A similar condition is found in the Binh Tri Thien Zone andthe southern area of the Dien Bien-Nghe An Zone, where theThien Nhan and the Xom Nha formations extend as small bands.The Thien Nhan Formation consists of argillaceous-siliceous shale,chert, fine-grained sandstone, and siltstone, in which were foundconodonts (Ozarkodina (Spathognathodus) sp., Palmatolepis sp.) andbrachiopods. Similar deposits occur in the Tuyen Hoa and MinhHoa Districts, (Quang Binh Province), where occur black argilla-ceous shale, chert and siltstone, siliceous siltstone, thin manganeseinterbeds, which are used to characterize the Ngoc Lam Forma-tion. Here have been found the conodont Palmatolepis subrectaand the brachiopod Calvinaria cf. C. megistanu. The Xom NhaFormation consists of dark grey, light grey stylolitic limestonecontaining abundant corals (Scoliopora denticulata, Thamnoporapolyforata, Temnophyllum isetense), stromatoporoids (Stachyodescostulata, S. angulata) and conodonts (Palmatolepis gigas, P. trian-gularis, P. marginifera).

Thus, in the above-mentioned Upper Devonian formations, thebenthic fauna and conodonts coexist in the carbonate sediments.These carbonate formations were possibly deposited in a deepwater environment on the slope of the continental shelf.

3.2.4. Facies of the Devonian deposits in the South Viet NamRegion

Devonian deposits rarely occur in the South Viet Nam Region,except in isolated areas. Moreover, their stratigraphic relationswith the underlying and overlying deposits are unknown; there-fore, they are scarcely studied. Fossiliferous Devonian sedimentsonly occur in a small area in the West of the Kon Tum Block, inthe southern part of Central Viet Nam. There, the Cu Brei Forma-tion (D1 cb) consists of terrigenous sediments in its lower part, withconglomerate, gritstone in the bottom, and carbonate deposits con-taining corals, stromatoporoids in its upper part (Tong-Dzuy Thanhet al., 2007). Perhaps the terrigenous-carbonate of the Cu Brei For-mation belongs to an onshore, shallow water facies that is similarto the ones in Viet-Lao Region. The Hon Heo Formation in westernNam Bo Zone (Kien Giang Province) mainly consists of sandstone.It is supposedly referred to the Devonian and belongs to the sub-continental facies, based on the presence of plant remains referredto Psilophyton sp. and Taeniocrada? sp.

4. Remarks


4.1 Due to the extensive investigations carried out in the lastdecades, new achievements of the Silurian and Devonianstratigraphy of Viet Nam are well ascertained. All Silurian andDevonian units have been well described on the basis of the

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https://www.researchgate.net/publication/292751484_Tai_lieu_moi_ve_tram_tich_Devon_trong_khoi_Bac_Son_New_data_on_Devonian_deposits_in_the_Bac_Son_massif?el=1_x_8&enrichId=rgreq-e809e99f168b313b450cad79320e6be1-XXX&enrichSource=Y292ZXJQYWdlOzI1OTEyMjkyODtBUzoyODg3OTUzMDQ5NzIyOTFAMTQ0NTg2NTU3NTA0Mw==


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study of the lithology, paleontology, facies of the sediments,and of their stratigraphic sequences.

.2 On the stratigraphic relations of the Silurian and Devonian unitsof Viet Nam- In all studied sections of Viet Nam there are no gaps or uncon-

formities between the Ordovician and Silurian have beenobserved. The conformable relation is obviously expressedin the sequences of the Ordovician–Silurian formations, suchas the Co To (O-S ct) and Tan Mai (O-S tm) formations in theQuang Ninh Zone, the Phu Ngu Formation (O-S pn) in the EastBac Bo Zone, the Sinh Vinh Formation (O-S sv) in the West BacBo Zone, and the Song Ca (O3-S2 sc) and Long Dai (O2-S2 ld)formations in the Viet-Lao Region.

- In the East Bac Bo and the Quang Ninh zones of the Bac BoRegion, and in the Binh Tri Thien Zone of the Viet-Lao Regionthe lowermost units of the Devonian with the basal conglom-erate are unconformable lying upon the Silurian units. Whilein the West Bac Bo Zone and in the Dien Bien-Nghe An Zone ofthe Viet-Lao Region the relation between Silurian and Devo-nian units seem to be conformable.

- There are no gaps or unconformable relations are expressed inthe sequence between the Devonian and Carboniferous units.

.3 In the most cases the Silurian deposits consist of the sandstone,shale and limestone containing benthos fauna, which confirmthe marine shallow water environment of the sedimentationprocess of these units. The deep-water facies of the Siluriandeposits is characterized for the Co To and Tan Mai formationsin the Quang Ninh Zone, and the Phu Ngu Formation in theEast Bac Bo Zone only. Perhaps the Co To and Tan Mai forma-tions in the Quang Ninh Zone were taken shape, in a forearcsedimentary basin, and originated from a regenerated orogenicprocess (Nguyen Xuan Khien, 2000). This situation is similar tothe Silurian deposits in the adjacent area of the Southeast China(Wang Hongzhen, 1985).

.4 By the lithological and paleontological compositions the Devo-nian deposits of the Bac Bo Region, especially of the East BacBo Zone, are similar to the ones of the Guangxi (South China).This similarity is obviously expressed in the Si Ka, Bac Bun andMia Le formations of the Bac Bo Region and the Lianhuashan,Nakaoling and Yukiang formations, respectively, of the SouthChina (Wu Yi et al., 1987; Yang Si-pu et al., 1981).

.5 Most Devonian units distributed in the North and the Cen-tral Viet Nam consist of self shallow water sediments, andapparently they were deposited in a passive marginal marineenvironment. The coarse clastic continental or subcontinentaldeposits are distributed only in some areas of the East Bac Boand of the Quang Ninh zones of the Bac Bo Region, and in thesouth of the Binh Tri Thien Zone. This situation suggests theinfluence of the Caledonian movement at the end of the Silurianperiod that called the Guangxi movement in South China.

cknowledgments

The authors are grateful to the National Foundation for Sci-nces and Technology Development of Viet Nam (NAFOSTED) forhe effective support to the Projects 105.01.79.09 and 105.06.60.09.

e are thankful to Prof. A.J. Boucot (Oregon State University, USA)nd Prof. Yu Chang-min (Institute of Palaeontology and Geology,anking. China) for their valuable criticisms and recommenda-

ions. Nguyen Thi Thu Cuc and Nguyen Thuy Duong would like tohank the TRIG A project of the Hanoi University of Science (Viet-


doi:10.1016/j.jog.2011.10.001

am National University, Hanoi, Viet Nam) for the support to studyission at the University of Greifswald, Germany. We are very

rateful to an anonymous reviewer for their valuable commentsnd suggestions, which helped us to improve the final version of

PRESSynamics xxx (2011) xxx– xxx

this manuscript. Interesting discussions of Prof. Tran Van Tri (Geo-logical Association of Viet Nam) in the preparation of the paper aremuch appreciated.

References

Brady, S.J., Selden, P.A., Doan Nhat Truong, 2002. A new Carcinosomatid Eurypteridfrom the Upper Silurian of Northern Vietnam. Palaeontology 45 (5), 897–915.

Bui Phu My (Ed.), 1978. Geological Maps on scale 1: 200 000 with explanatory note.Lao Cai and Kim Binh Sheet. General Department of Geology of Viet Nam, HaNoi.

Dang Tran Huyen, 1979. Dan lieu moi ve dia tang Devon vung Dong Van (New dataon the Devonian stratigraphy of the Dong Van area). Dia chat (Geology) 142,22–24, Ha Noi.

Dang Tran Huyen, Nguyen Dinh Hong, Vuong Van Ich, Luong Hong Huoc, 1980. Cactram tich Devon vung Tan Lam-Cu Bai, Binh Tri Thien (Devonian sediments inthe Tan Lam-Cu Bai, Binh Tri Thien Province). Cac khoa hoc ve Trai Dat (EarthSciences). 3/2, 26–28. Ha Noi.

Dovjikov, A.E. (Ed.), 1965. Geologia Severnogo Vietnama (Geology of North VietNam). Tong cuc Dia chat. General Department of Geology, Ha Noi, Ha Noi (inRussian), 584 pp.

Hoang Xuan Tinh (Ed.), 2001. Geological Maps on Scale 1:200 000 with ExplanatoryNote. Bao Lac Sheet. Department of Geology of Viet Nam, Ha Noi.

Janvier, P., Gerrienne, P., Tong Dzuy Thanh, 1989. Les Placodermes, Arthropodes etLycophytes des grès dévoniens de Dô Son (Haïphong, Viêt Nam). Géobios 25 (5),625–639.

Janvier, P., Racheboeuf, P., Nguyen Huu, H., Doan Nhat, T., 2003. Devonian fish (Pla-codermi, Antiarcha) from Tra Ban Island (Bai Tu Long Bay, Quang Ninh Province,Vietnam) and the question of the age of the Do Son Formation. Journal of AsianEarth Sciences 21, 795–801.

Janvier, P., Ta Hoa Phuong, 1999. Les Vertébrés (Placodermi, Galeaspida) duDévonien inférieur de la coupe de Lung Co-Mia Le, province de Ha Giang, Viet-nam. Geodiversitas 21 (1), 33–67.

Janvier, P., Tong-Dzuy Thanh, 1998. The Silurian and Devonian Vertebrate of VietNam: A new review. Journal of Geology (Geological Survey of Viet Nam) B. 10–11,18–28.

Janvier, P., Tong-Dzuy Thanh, Ta Hoa Phuong, 1993. A new Early Devonian Galeaspidfrom Bac Thai Province, Viet Nam. Palaeontology 36 (2), 297–309.

Lantenois, H., 1907. Note sur la géologie de l’Indochine. Mémoires de la SociétéGéologique de France, Paris. 4/1, 56 p.

Le Duy Bach, Nguyen Van Hoanh (Eds.), 1995. Geological Maps on Scale 1:200 000with Explanatory Note. Khang Khay-Muong Xen Sheet. Department of Geologyof Viet Nam, Ha Noi.

Le Thanh Huu, Vu Xuan Luc, 2005. Thanh lap he tang Ket Hay tuoi Ordovic muon(?)–Silur som o vung Tay Nam nhom to Yen Chau (Estblishment of the Ket HayFormation Late Ordovician (?)—Early Silurian in age in the South-West area ofthe Yen Chau Sheet group). Dia Chat (Geology) 305, 16–23.

Le Thac Xinh, Hoang Tri Nghi, 1964. Cau tao dia chat vung Ta Khoa (Geologicalstructure of the Ta Khoa area). Dia chat (Geology) 33, 9–12, Ha Noi.

Long, J., Burrett, C., Pham Kim Ngan, Janvier, P., 1990. A new botriolepid antiarch(Pisces, Placodermi) from the Devonian of Do Son peninsula, Northern Viet Nam.Alcheringa 14, 181–194.

Nguyen Cong Luong (Ed.), 2001a. Geological Maps on Scale 1:200 000 with Explana-tory Note. Mong Cai Sheet. Department of Geology of Viet Nam, Ha Noi.

Nguyen Cong Luong (Ed.), 2001b. Geological Maps on Scale 1:200 000 with Explana-tory Note. Ha Long Sheet. Department of Geology of Viet Nam, Ha Noi.

Nguyen Huu Hung, Doan Nhat Truong, Dang Tran Huyen, 1991. Tai lieu moi ve tramtich Devon trong khoi Bac Son (New data on Devonian deposits in the Bac Sonmassif. Cac khoa hoc ve Trai Dat (Earth Sciences) 3 (2), 33–39, Ha Noi.

Nguyen Huu Hung, Doan Nhat Truong, Nguyen Duc Khoa, 1995. Dia tang cac tramtich Devon va Devon thuong-Carbon ha o Bac Trung Bo Viet Nam (Stratigraphyof the Devonian and Upper Devonian-Lower Carboniferous in North Central VietNam). Dia chat va Khoang san (Geology anf Mineral Resources). 4, 17–30. Viennghien cuu Dia chat va Khoang san (Institute of Geology and Mineral Resources),Ha Noi.

Nguyen Huu Hung, Nguyen Dinh Hop, Nguyen Duc Khoa, 1988. Tai lieu moi vetram tich Silur thuong va Eifel-Givet trong to Thanh Son-Thanh Thuy (New dataon Upper Silurian and Eifelian-Givetian sediments in Thanh Son – Thanh Thuysheet). Tap chi Dia chat (Journal of Geology) 184–186, 54–55.

Nguyen Huu Hung, Ta Hoa Phuong, Janvier, P., 2004. Tai lieu moi ve dia tang Devono vung duyen hai Dong Bac Bo (New data on the Devonian stratigraphy in thecoastal area of East Bac Bo). Dia chat (Journal of Geology) 281, 1–10.

Nguyen Huu Hung, Ta Hoa Phuong, Nguyen Thi Thuy, 2007. Tram tich Devon odoi Quang Ninh (The Devonian sediments in the Quang Ninh Zone). Dia chat(Geology) 302, 43–56. Ha Noi.

Nguyen Huy Mac, Pham The Hien, 1972. Mot so van de dia chat o quan dao Co Tova lan can trong vinh Bac Bo (Some geological problems of Co To Archipelagoand adjacent islands in the Bac Bo Gulf). Sinh vat-Dia hoc (Biology and Earth


Sciences) X/1–4, 37–42, Ha Noi.Nguyen Kinh Quoc (Ed.), 2001. Geological Maps on Scale 1:200 000 with Explanatory

Note. Bac Can Sheet. Department of Geology of Viet Nam, Ha Noi.Nguyen Quang Hap, 1967. Cac tram tich vung ria dong bac Ha Noi va du. doan su.

phat trien cua chung vao mien trung (Sedimentary formations in the Northeast

dx.doi.org/10.1016/j.jog.2011.10.001








https://www.researchgate.net/publication/213774546_The_Devonian_System_in_China?el=1_x_8&enrichId=rgreq-e809e99f168b313b450cad79320e6be1-XXX&enrichSource=Y292ZXJQYWdlOzI1OTEyMjkyODtBUzoyODg3OTUzMDQ5NzIyOTFAMTQ0NTg2NTU3NTA0Mw==










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G

f Geod

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P

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T

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T

T

T



margin of the Ha Noi depression and prognosis of their development into thedepression). Dia chat (Geology) 69–70, 9–21, Ha Noi.

guyen Van Hoanh (Ed.), 1995. Geological Maps on Scale 1:200 000 with Explana-tory Note. Xieng Khoang—Tuong Duong Sheet. Department of Geology of VietNam, Ha Noi.

guyen Van Phuc, 1998. Lower Devonian Graptolites from Muong Xen area (Noth-west part of Central Viet Nam. Journal of Geology (Journal of the Department ofGeology and Minerals of Viet Nam) B/11–12, 29–40, Ha Noi.

guyen Vinh (Ed.), 1978. Geological Maps on Scale 1:200 000 with Explanatory Note.Yen Bai Sheet. General Department of Geology of Viet Nam, Ha Noi.

guyen Xuan Bao (Ed.), 1978. Geological Maps on Scale 1:200 000 with ExplanatoryNote. Van Yen Sheet. General Department of Geology of Viet Nam, Ha Noi.

guyen Xuan Duong (Ed.), 1996. Geological Maps on Scale 1: 200 000 with Explana-tory Note. Le Thuy-Quang Tri Sheet. Department of Geology of Viet Nam, HaNoi.

guyen Xuan Khien, 2000. Mot so ket qua nghien cuu moi ve cac tram tich quan daoCo To (Quang Ninh) (Some new results from the study on the sediments of theCo To archipelago (Quang Ninh Province). Dia chat va Khoang san (Geology andMineral Resouces). 7, 55–60. Vien Dia chat va Khoang san (Institute of Geologyand Mineral Resources). Ha Noi.

ham Dinh Long (Ed.), 2001. Geological Maps on Scale 1:200 000 with ExplanatoryNote. Long Tan-Chinh Xi Sheet. Department of Geology of Viet Nam, Ha Noi.

ham Dinh Long (Ed.), 2002. Geological Maps on Scale 1:200 000 with ExplanatoryNote. Tuyen Quang Sheet. Department of Geology of Viet Nam, Ha Noi.

ham Thanh Binh, Nguyen Cong Luong, 1999. Kieu mat cat co ban he tang Co To-daoThanh Lan (Main sections of the Co To Formation in the Thanh Lan Island). Diachat va Khoang san Viet Nam (Geology and Mineral Resources of Viet Nam). III,9–14. Lien doan Ban do Dia chat Mien Bac (North Viet Nam Geological MappingDivision). Ha Noi.

han Cu Tien, Tran Quoc Hai, Le Dinh Huu, Phan Viet Ky, Bui Phu My, Nguyen Vinh,1977. Chu giai Ban do dia chat Tay bac Viet Nam, loat to ba�n do Song Da ty le 1:200.000 (Legend of the geological map of the Ðà River sheet series of NW Vie. tNam on 1: 200.000 scale). In Nhung van de dia chat Tay Bac Viet Nam (Problemsof the Geology of the Northwestern Region), 9–64. Nha xuat ban Khoa hoc va Kythuat (Sientific and Technique Pubishing House). Ha Noi.

acheboeuf, P.R., Janvier, P., Ta Hoa Phuong, Vannier, J., Wang, S.Q., 2005. LowerDevonian vertebrates, arthropods and brachiopods from northern Vietnam.Geobios 38 (2005), 533–551.

acheboeuf, P.R., Tong-Dzuy Thanh, 2000. Lower Devonian Chonetoidean bra-chiopods from Bac Bo, North Viet Nam. Paleontology 43 (6), 1039–1068.

aurin, E., 1956. Indochine. In “Lexique stratigraphique International”. III/6a. CentreNational de la Recherche Scientifique, Paris. 140 pp.

a Hoa Phuong, 1998. Upper Devonian conodont biostratigraphy in Viet Nam. Jour-nal of Geology (Journal of the Department of Geology and Minerals of Viet Nam)B/11–12, 76–84, Ha Noi.

a Hoa Phuong, Le Van Manh, 1996. Nhung tai lieu moi ve mat cat chuan cua hetang Bo Hieng (New data on the stratotype of Bo Hieng Formation). Dia chat(Geology) A/232, 28–33, Ha Noi.

ong-Dzuy Thanh, 1993. Major features of Devonian stratigraphy in Viet Nam withremarks on paleobiogeography. Journal of Geology (Journal of the Departmentof Geology and Minerals of Viet Nam) B/1–2, 3–18, Ha Noi.


doi:10.1016/j.jog.2011.10.001

ong-Dzuy Thanh, Boucot, A.J., Rong Jia-yu, Fang Zong-jie, 2001. Late Silurian marineshelly fauna of Central and Northern Vietnam. Geobios 34 (3), 315–338.

ong-Dzuy Thanh, Cai Chong-yang, 1995. Devonian flora in Viet Nam. Journal ofGeology (Journal of the Department of Geology and Minerals of Viet Nam) B/5–6,105–113, Ha Noi.


Tong-Dzuy Thanh, Dang Tran Huyen, Nguyen Dinh Hong, Nguyen Duc Khoa, NguyenHuu Hung, Nguyen The Dan, Ta Hoa Phuong, Pham Kim Ngan, Doan Nhat Truong,1988. Stratigrafia i tselenteraty Devona Vietnama (Devonian stratigraphy andCoelenterata of Vietnam). I. Stratigrafia. Nauka. Novosibirsk (in Russian). 184pp.

Tong-Dzuy Thanh, Janvier, P., 1990. Les Vertébrés du Dévonien inférieur du Bac Booriental (province de Bac Thai et Lang Son, Viêt Nam). Bull. Mus. Nat. Paris. 4esér., 12. Section C, no 2, 143–223. Paris.

Tong-Dzuy Thanh, Janvier, P., 1994. Early Devonian fishes from Trang Xa (BacThai, Vietnam), with remarks on the distribution of the Vertebrata inthe Song Cau Group. Journal of Southeast Asian Earth Sciences 10 (3–4),235–243.

Tong-Dzuy Thanh, Janvier, P., Doan Nhat Truong, 1994. Première découverte d’unPlacoderme (Vertebrata) dans le Dévonien du bloc Indochinois (Trung Bo, VietNam). Bulletin du Museum d’Histoire Naturelle. C/16, 259–279. Paris.

Tong-Dzuy Thanh, Janvier, P., Ta Hoa Phuong, Doan Nhat Truong, 1995. LowerDevonian biostratigraphy and vertebrates of the Tong Vai Valley, Vietnam.Palaeontology 38 (1), 169–186.

Tong-Dzuy Thanh, Ta Hoa Phuong, 1994. New data for correlation of Early Devo-nian bearing the Euryspirifer tonkinensis fauna in Vietnam and South China.Subcommission on Devonian Stratigraphy. Newsletter N0 11, 69.

Tong-Dzuy Thanh, Ta Hoa Phuong, Boucot, A.J., Goujet, D., Janvier, P., 1997.Vertébrés siluriens du Viêt Nam Central. C. R. Acad. Sci., Paris, 324, ser.IIa, 1023–1030.

Tong-Dzuy Thanh, Than Duc Duyen, Nguyen Huu Hung, Bui Phu My, 2007. Discoveryof the Lower Devonian fossiliferous sediments in the Kon Tum Block (South VietNam). Journal of Asian Earth Sciences 29, 127–135.

Tong-Dzuy Thanh, Vu Khuc (Eds.), 2006. Stratigraphic Units of Viet Nam. Ha NoiNational University Publishing House, p. 526, Ha Noi.

Tran Thi Chi Thuan, Fontaine, H., 1968. Note sur la province de Quang Tri et descrip-tion de quelques brachiopodes. Viet Nam Ðia chat Khao luc 11, 59–81, Sai Gon.

Tran Tinh (Ed.), 1996. Geological Maps on Scale 1:200 000 with Explanatory Note.Ha Tinh-Ky Anh Sheet. Department of Geology of Viet Nam, Ha Noi.

Tran Van Tri, Nguyen Dinh Uy, Tran Dinh Nhan, Do Tuyet, 1972. Tai lieu moi ve cautao dia chat quan dao Co To (New data on the geological structure of the Co Toarchipelago). Dia chat (Geology). 105, 1–4. Ha Noi.

Tran Van Tri, Nguyen Van Chien, Le Van Cu, Duong Xuan Hao, Le Hung, Vu Khuc,Pham Duc Luong, Pham Kim Ngan, Tran Dinh Nhan, Hoang Huu Quy, Tong DuyThanh, Phan Truong Thi, Trinh Tho, Nguyen Thom, Nguyen Xuan Tung, NguyenDinh Uy, 1977. Dia chat Viet Nam-Phan Mien Bac (Geology of Viet Nam–NorthPart). Nha xuat ban Khoa hoc va Ky thuat. Scientific and Technical PublishingHouse, Ha Noi. 355 pp.

Tran Van Tri, Vu Khuc (Eds.), 2009. Dia chat va Tai nguyen Viet Nam (Geology andMineral Resources of Viet Nam). NXB Khoa hoc Tu nhien va Cong nghe. NaturalSientific and Tecnological Pubishing House, Ha Noi, p. 589.

Vu Khuc, Bui Phu My (Eds.), 1990. Dia chat Viet Nam. Tap I. Dia tang (Geology of VietNam. Part I. Stratigraphy). Tong cuc Mo-Dia chat. Department of Geology andMining, Ha Noi, p. 378.

Wang Hongzhen (Ed.), 1985. Atlas of the palaeogeography of China (in Chinese withEnglish Explanation 28 pp.).

Wu Yi, Zhou Huailing, Jiang Tingcan, Fang Dannian, Huang Wusheng, 1987.


Sedimentary Facies, Paleogeography and Relatively Mineral Deposits ofDevonian in Guangxi. Guangxi Poeples Publishing House, Guangxi, China,292 pp.

Yang Si-pu, K., Kiang, Hou Hong-fei, 1981. Devonian system in China. GeologicalMagazine 118 (2), 113.

dx.doi.org/10.1016/j.jog.2011.10.001




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Silurian and Devonian in Vietnam—Stratigraphy and facies

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