ISSN 0866 - 7381

Journal ofGEOLOGYSPECIAL ISSUE

PROCEEDINGS OF THE INTERNATIONAL SYMPOSIUM GEOLOGY OF SOUTHEAST ASIA

AND ADJACENT AREAS 1-9 November 1995, Hanoi

Series B - ° 5 61995

GEOLOGICAL SURVEY OF VIETNAM HANOI

CONTENTS

STRATIGRAPHY

BERNARD BATTAIL, JEAN DEJAX, PHILIPPE RICHIR,PHILIPPE TAQUET & MONETTE VF.’RAN

New data on the continental Upper Permian in the area of Luang-Prabang, Laos 11

H. FONTAINE, IBRAHIM B.A. & D. VU KHUC

Triassic limestones of Southwest Kelantan (east and south of Pos Blau) and north Pahang (Merapoh area), penisular Malaysia 16

NGUYEN NGOC

Stratigraphic significance of some geologic events for the subdivision and correlation of Pliocene-Quaternary sediments in the coastal zone of Vietnam 31

PHAN CU TIEN & J.M.DICKINS

Subdivision and correlation of the Permian stratigraphy of Vietnamand adjacent regions in Southeast Asia and Eastern Asia. 37

JOHN H. SHERGOLD

Correlation of the Cambrian biostratigraphy of Northern and Central Australia with that .of Southern and Eastern Asia 48.

G.R. SHI, N.W. ARCHBOLD & FANG ZONGJIE

The biostratigraphical and palaeogeographical significance of an Early Permian brachio- pod fauna from the Dingjiazhai Formation, Baoshan block, western Yunnan, China 63

FRANCES C.P. SPILLER & IAN METCALFE

Palaeozoic and Mesozoic radiolarian biostratigraphy of peninsular Malaysia..... 75

ТА HOA PHUONG & DOAN NHAT TRUONG

Peliminary studies on the boundaries of Famennian stage in Vietnam 94

TONG-DZUY THANH & CAI CHONG-YANG

Devonian Flora of Vietnam / 5~

TRINH DZANH

Stratigraphic correlation of Neogene sequences of Vietnam and adjacent areas 114

WANG CHENG-YUAN

Upper Permian Conodont Standard Zonation and Correlation with other Fossil Groups 121

YANG SHOUREN

Ladinian-Carnian Conodonts and their Biostratigraphy in Asia 127

YIN HONGFU, ZHANG KEXIN, WU SHUNBAO & PENG YUANQIAO

Global correlation and defination of the Permian-Triassic boundary (PTB) 139

Journal of GEOLOGY EDITORIAL OFFICE

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EDITORIAL BOARD

Editor-in-chief: TRẰN VÀN TRỊ

Members: LÊ Đ Ú t AN, PIIẠM VAN AN, NGUYEN XUÂN BAO, NGUYEN GIAO, v ũ NGỌC HẢI (Deputy Editor-in-chief), VỮ KHỦC, (Deputy Editor-in-chief), NGUYEN NGHIÊM MINH.TẪNG Ml ỦI, VÕ CÔNG NGHIỆP, NGUYỄN TIẾN THÀNH, JONG DUY THANH, TRAN MINH THẾ, PHAN TRUỠNG THỊ, PHAN CựTIẾN, LÊ VÀN TRẢO, NGUYỄN KHẮC VINH, NCỈUYẺN TRỌNG YÊM

Secretary: BÙI ĐỨC THẮNG

This issue is designed for the publication of proceedings and abstracts of papers presented in the International Symposium on Geology of SE Asia and adjacent areas (1-9 November 1995, Hanoi), organized by the VietnamNational Committee for IGCP, Geological Survey of Viet Nam and IGCP Projects 306 (Stratigraphic correlation in SE Asia), 321 ( Gondwana dispersion and Asian accretion) 359 ( Correlation of Tethyan, Pacific and Gondwanan Permo-Triassic) Coleaders with the co-operation of the Geological Association of Viet Nam and Hanoi National University.

Proceedings of the IGCP Symposium on Geology of SB Asia, Hanoi, XI/1995

Journal of GEOLOGY Series B. No. 5-6/1995, p.105

DEVONIAN FLORA OF VIETNAM

TONG-DZUY THANH1, CAI CHONG-YANG2

1. Department o f Geology. Vietnam National University.90, Nguyen Trai Str. Dong Da. Ha Noi. Viet Nam.

2. Nanjing Institute o f Geology and Palaeontology , Academia Sinica.39, East Beijing Road, Nanjing,2]0008. P.R.China.

Abstract:

Lower Devonian

In the North o f Central Vietnam (Phu Puoc Mt, near Ban Keo Muong, West of Nghe An Province) some Lower Devonian plant fossils were discovered more than 30 years ago and they consist o f the remains o f the genera Zosterophyllum Hostimella, Aphyllopteris (identification o f N.M.Petrosian, see Dovjikov et al. 1965). G.P.Radchenko identified another remain as Archaeopteris collected about 3.5 km southeastward from the above-mentioned locality (Dovjikov et al. 1965). Observing the photos o f this remain, Cai Chong-yang suggests that it should be a spike o f Lower Devonian Zosterophyllum, but not the sterile portion of Archaeopteris.

Remains of Taeniocrada ? were recently collected in the rocks o f the upper part, o f the Bo Hieng Formation, in the downstream o f the Song Da River. According to the Brachiopod and Coral assemblages this formation must be Upper Silurian, but not Lower Devonian. In the Sika Formation (Lower Devonian) of North Vietnam, near Vietnam-China border, J. Deprat (1915) collected some plant remains and identified them as Bytrotrephis aff. antiqua.

Middle Devonian

A numerous collection of plant remains has been gathered from the Dong Tho form ation, on the bank o f the Hoi Da stream, near Minh Le railway station, Quang Binh Province (Central Vietnam). It consists mainly o f the remains of Bergeria or Knorria state fc/.Protolepidodendron sp., cf. Lepidodendropsis sp.). Apart from these Givetian plant remains; abundant spore assemblage, identified by Dr. Wang Yi, also indicates Givetian age o f the bearing fossil formation.

Some remains o f Bergeria fc/.Lepidodendropsis sp.) were discovered in the tandtfcne o f the Do Son peninsula, Hai Phong City and o f the Tan Lap village, ta n g Son, province. In the Do Son Formation the plant remains associate with th f fish remains o f Bothriolepis sp., Vietnamaspis trii. In addition, some Bivalves were also found in the formation. This assemblage o f invertebrate, vertebrate and piant fossils indicates (he Givetian age o f the fossil bearing rocks.

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INTRO DUCTIO N

The first Devonian plant remains in Viet Nam had been discovered by French geologist J. Deprat (1915) in the Sika Formation -- in association with fish remains Asterolepis, Homosleus sp.. They were identified as Bytrotrephis aff. antiqua and dated as Ordovician in age (Deprat 1915, Saurin 1956). New stratigraphical data show that the Sika Formation is the Lowest strata of Lower Devonian in North Viet Nam (Tong-Dzuy Thanh 1988, 1993). During the last 30 years numerous Devonian plant remains have been gathered from different stratigraphic levels of the North and the Center of Viet Nam but palaeontologically they are not well studied yet. The preliminary paleontological study on Devonian plant remains and their stratigraphic roles in Viet Nam are the purpose of this communication.

The present works have been carried out in the framework of the Viet Nam Fundamental Research Program in the fields of Natural Sciences (KT 04). Thanks to its grant, the authors have collected fossils and discussed Devonian sequences concerning the plant remains in Viet Nam.

O UTLINES ON STRATIG RAPH Y

Devonian sediments are widespread in the North and the Center of Viet Nam. Being judged from their facies and sequences they are distinguished in the distribution in two different regions. The first one is the area from the North of the Song Ma fault, belonging to the South China Block. The second spreads from the Song Ma fault toward the South of Mid-Center of Viet Nam up to the Hue - Da Nang area, belonging to the Indochina block.

IN THE NORTH OF VIET NAM

Devonian sequences of the North region are a little different from the North to the South. In the North, near the Vietnam-China state border the Devonian sequences begin by Sika Formation, which consists of the

conglomerates, sandstone and marls of red colour that are compared to the Old Red Sandstone and the Lianhuashan Formation in South China (Tong-Dzuy Thanh, 1993). Here and there the poor preserved remains of fish Galeaspid and plant fossils were collected(Fig.l).

In conformity with the Sika Formation, the Devonian sequences are characterized by the marine sediments, which are widespread in the all territories of North Viet Nam (Bac Bo or Tonkin):

- Bac Bun' Formation consists of dark shales and marls bearing the Howitia wangi fauna. This marine fauna is very close to the one of the Orientospirifer wangi assemblage in the Southern China. Biostratigraphically it is correlated with the Nagaoling Formation in South China. A part from the invertebrates, a lot of vertebrates are recently described (TONG-DZUY Thanh & Ph.JANVIER 1990).

- Mia Le Formation is very widespread in the North of Viet Nam. Invertebrate marine fossils are abundant in the rocks of the beds of shale, marl, and limestone lenses or beds of it, such as Brachiopods, Corals, Trilobites, Bivalves, Crinoids and other fossils. This assemblage is well-known as the Euryspirifer tonkinensis fauna that is wide spread not only in North Viet Nam but also in South China. The endemic forms are very common in the components of this assemblage. Perhaps the most distinguished one is the Brachiopod genus Dicoelostrophia that occurs both in South China and North Viet Nam. The Mia Le Formation is dated as Praguian in age (Tong- Dzuy Thanh 1993, Ta Hoa Phuong 1994).

- Ban Pap Formation, Emsian - Givetian in age, plays an important role in the Devonian of the North of Viet Nam. A lot of Coral, Brachiopod, Dacrioconarid and Conodont fossils from this formation were collected and well studied. In the Tan Lap - Bac Son area (Lang Son Province, near Viet Nam - China state Border) the Middle Devonian terrigenous beds are newly discovered. In the later Nguyen Huu Hung ami Doan Nhat Truong have newly discovered some plant fossil remains.

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Fig.l. Distribution of the Devonian in Viet namand Laos, Cambodia

&:• Fossiliferous DevonTain- deposits. b: Devonian with rarefossils. c: Supposed Devonian deposits.Plant remain outcrops: 1 . S i l u r i a n (Downstream of Song Da).2 . Low er D e v o n ia n (2a - Muong Xen area, 2b Sika area). 3 . G i e i i a n (3a - Do Son area. 3b - Tan Lap area. 3c - Hoi Da, Minh Le area)

- Upper most srata of Devonian in the North of Viet Nam consist mainly of limestones and cherts bearing abundant Conodont fossils. In, some areas these limestones forms the lower part of the Upper Devonian - Lower Carboniferous sections.

IN CENTRAL VIETNAM

The Devonian sequences are rather different from the ones of the Northern Viet Nam. The faciès and sequences of this region are distinguished in two types of the sections (Fig.l).

- The first section type occurs in the Song Ca area (West of Nghe An Province (Fig.l), where the Lower Devonian seems to be part of the Tay Trang Complex, which is Silurian - Upper Devonian in age. Just in this section some Lower Devonian interesting plant fossils had been collected in the sixties (see below).

More and more carbonate components take part in the sequences of Middle and Upper Devonian. A lot of Conodont samples are newly gathered and well studied, which serves as a good basis for the identification of the rock age.

- The second section type occurs in the Mid-Central Viet Nam, namely in the territory of the Quang Binh, Quang Tri and Thua Thien- Hue provinces.

Lower Devonian Tan I am Formation occurs in the West of Quang Tri province and may be also in the Thua Thien - Hue province. It consists o f sandstones and shales bearing Lingula with a thin bed of fine conglomerate in the bottom. The Rao £han Formation overlies the Tan Lam one and consists of sandstones, shales with rare Lower Devonian Brachiopds.

Eifelian Ban Giang Formation, overlying in concordance the Rao Chan one, composes of shists, mudstones and sandstones and a small limestone lens.

Givetian Mue Bai fossiliferrous Formation is well known in the Devonian o f the Central Viet Nam. It consists of sandstones, shales in

the lower part and sandstones with intercalation of limestone in the upper one.

Another Givetian Formation, namely Dong Tho, is the strata of transformational facies from Muc Bai Formation. Subcontinental coastal facies of this formation are manifest in the cross-bedding, in partcular in the Ly Hoa outcrop (Quang Binh Province), and in containing plant remains of it.

Upper Devonian in Central Viet Nam consists mainly o f limestone, some times with thin siliceous interbeds that take the lower part of the Upper Devonian - Lower Carboniferous sections.

PALEONTOLOGICAL DATA

Lower Devonian flora

There has been information available on the discovery of the flora remains of Bytrotrephis aff, antiqua and Cooksonia sp. in the Ska Formation, lowermost beds of Devonian in the North of Viet Nam (Saurin 1956; Tong-Dzuy Thanh.1988, Janvier et al.1987). Unfortunately no descriptions of those plant remains were published and these remains have not been found out yet. According to the Devonian stratigraphic data of Viet Nam (Tong Dzuy Thanh, 1993) the facies of the Sika Formation may correlate with the one of Lianhuashan and Posonchong ones in South China (Cai ('hong-yang & Li Xing-xue 1982, 1994).

Some plant fossils were discovered in the association with graptolite fossils in the thin- bedded yellow fine sandstones that are described now as the components of the Tay Trang Complex (Huoi Nhi Formation in the former papers) in the West of Nghe An Province, Central Viet Nam (Fig.l). These plant remains were identified by N.M. Petrosian as Zosterophyllum sp., Hostimella sp. Taeniocrada sp. Gosslingia sp. (Dovjikov et al. 1965). From the south slope of Pu Puoc Mt. Muong Xen district of Nghe An Province, some spores were identified as Protoleiosphaeridium angulatum Andr., Pr. flavum (Tim.) Andr., Pr. perfoliaturn ci. major Andr.(Tran Van Tri et al. 1977). The plant-bearing beds were supposed

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as Late Silurian in age. It is worth mentioning that all these plant remains are too poorly preserved to be well identified. Among them two axes with H-type branching are considered as the form of Zosterophyllum sp.,a leading plant fossil of the EarlyDevonian(Pl.I,Fig.l,2). Judging from the photo, we can see that there is not the fertile portion in the sample, so the suitable name of this fossil would be Zosterophyllum ? sp.

About 3.5 km southward from the above- mentioned locality, the better preservedspecimens were found in the similarsandstones and G ., P. Radchenko identified them as Archeopteris sp., an index fossil of Late Devonian (Dovjikov et al. 1965, Tran Van Tri et al. 1977). The photo of the later specimens shows that this plant remains should be a spike of Zosterophyllum instead of a sterile portion of Archeopteris.

It is clear that all the two above- mentioned bearing plant beds in the North of Central Viet Nam are Early Devonian in age.

In an early paper, Tong-Dzuy Thanh(1993) pointed out that the Upper Member of the Huoi Nhi Formation (Tay Trang Complex in these paper) is undoubtedly Lower Devonian. While the age of its Lower Member yielding graptolites and above-mentioned plant remains is not solved yet. The above data on flora study confirm Early Devonian age of them.

A plant remain has been recently discovered by Ta Hoa Phuong from the Bo Hieng Formation (in the Song Da downstream, West of the Northern Viet Nam). The preservation of the remain is very poor, so Cai Chong-yang identified it only as Taeniocrada? sp. The abundant association of Brachiopods and Corals shows that the Bo Hieng Formation is Later Stfurian in age. So may be the above- mentioned plant remains are the first flora remains of the Middle Paleozoic in Viet Nam. Moreover, it is difficult to identify this remain due to its poor preservation.

Middle Devonian FloraSome Middle Devonian plant remains in

poor preservation have been discovered in the North and also in the Central Viet Nam.

In North Viet Nam the first Middle Devonian collection of plant remains occurs in the Do Son peninsula, near Hai Phong City (Fig.l). In the ash-grey sandstones of the Do Son Formation the plant remains of Bergeria or Knorria (cf. Lepidodendropsis sp.) associate with the fish remains of Bothriolepis sp. The similar association also occurrs in the Xichong or Haikou Formation Gevetian in age of the West Yunnan (South China). Apart from the lower member of the Do Son Formation, Tong- Dzuy Thanh has collected Bivalves Schizodusl sp., Ptychopteria (Actinoptera) cf. hunanensis Zhang, Goniophora sp. indet. Fang Zongjie, who identifies the'se bivalve fossils, considers the bivalve-bearing bed as Givetian in age. It is worth pointing out that Ptychopteria (Actinoptera) hunanensis is a well-known species in the Givetian of China.(Chitzechiao Formation of Flunan and the equivalent formations of South China). All the above- mentioned data allow us to consider that the Do Son Formation is Givetian in age.

Due to the lack of data, in the former papers one of us considered that the Do Son Formation may be Givetian - Frasnian in age (Tong Dzuy Thanh 1993). All the mentioned data here, in this paper, allow us to rectify the age of the Do Son Formation as Givetian.

In the Bac Son district (F ig.l), Lang Son Province (not far from the Viet Nam-Chinese state Boundary) Nguyen Huu Hung has collected remains of Bergeria (cf. Lepidodendropsis sp.). Cai Chong-yang, who has identified these remains, suggests that their bearing beds, that are Tan Lap Formation, are also Givetian in age.

A reliable collection of Givetian plants was discovered in the Hoi Da outcrop of the Dong Tho Formation, near Minh Le railway bridge, Quang Binh Province. The plant fossils are also poorly preserved in the Bergeria or Knorria state and compose of cf. Protolepidodendron sp. (F ig.l. PI. I, Fig. 5,5a), cf. Lepidodendropsis sp. (PI. I, Fig. 5, 5b, 6-8). Protolepidodendron is an index fossil plant of the Middle Devonian. Lepidodendropsis is the leading genus of the

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Givetian assemblage in both South and North China (Cai Chong-yang & Li Xing-xue, 1994).

The Givetian age of the plant fossil- bearing beds conforms to the spore assemblage associated with the plant remains. From the same Hoi Da outcrop Wang Yi identified the following spores: Apiculatisporites sp.,Geminospora spp., Grandispora sp., Favispora cf. rotunda Lu, Gymbosporites magnifica (McGregor) McGregor et Camfield, Apiculiretusispora sp., Chelinospora cf. rarireticulata Lu, Costazonotriletes latidentatus Lu, Archaeozonotriletes variabihs Naumova, Tholisporites densus McGregor, Aneurospora goensis Streel, Hvstricosporites sp., Ancyrospora involucra Owens, Retusotriletes sp., A. incisa (Naumova) Lu, A. tennicaulis Lu.

The above-mentioned spores are mostly discovered in the Givetian of East Yunnan, China. Among them the spores of two genera Ancyrospora and Geminospora are the predominant elements, occupying about 30% of the collection. Cymbosporites magnifica is widespread in the Haikou Formation (Givetian) in East Yunnan (Lu Lichang, 1980,1988) and is one of the leading species of the Mid-Givetian spore assemblage - Geminospora Lemurata - Cymbosporites magnifica (LM) in the Old Red Sandstone Continent and adjacent regions (Richardson and McGregor, 1986). Another species, Archaeozonotriletes variabilis is also an important element of LM zone (Richardsom and McGregor, 1986), which is common in the Givetian of East Yunnan (Lu Lichang, 1980, 1988) and Canada as well as Australia (McGregor and Playford, 1992). In addition, a few species, such as Costazonotriletes latidentatus, Favispora cf. rotunda, Chelinospora rarireticulata, Ancyrospora incisa, A. tennicaulis are only found from the Haikou Formation of East Yunnan, China (Lu Lichang, 1980,1988).

About less than 10 km Eastward from the Hoi Da outcrop, in the Ly Hoa Cap (F ig.l)traversed by highway N^ 1 the Dong Tho Formation consists of sandstones with rare argilaceous lenses. From this area, interesting

fish remains were discovered and studied, some plant remains were also collected, but due to their very poor preservation, they could not be identified. In the former papers,as in the case of the Do Son Formation, the Ly Hoa sandstones and the Dong Tho Formation in common are identified as Givetian-Frasnian in age(Tong-Dzuy Thanh 1993, Tong-Dzuy Thanh & P. JANVIER et al.1994).

The new data mentioned here, in this paper, show that the plant bearing beds, that are Dong Tho Formation, must be Givetian in age.

CO NCLUSIO NS

The Devonian plant fossils in Viet Nam have been mentioned for a long time and they must play an important role in the stratigraphy of the region. However, up to now there has been no special study on these fossils and the present paper is only the first attempt to illuminate their role in the Devonian stratigraphy of Viet Nam.

Two Devonian plant assemblages arc observed, the first is Lower Devonian collection in the Song ( ’a area (North of Central Viet Nam). The second consists of three Givetian collections: Do Son and Ian Lap in the North of Viet Nam, and Hoi Da (Minh Le area, Quang Hinh Province of Central Viet Nam).

The rectification of the name of Zosrerophyllum sp. instead ofArchaeopteris sp. confirms the Early Devonian age of their bearing-beds of the Tay Trang Complex in the West of Nghe An Province.

The Do Son and the Dong Tho Formations was also rectified as Givetian in age by the new result of Flora studies.

ACK NO W LEDG M ENT

The present authors express their gratitude to the Viet Nam Fundamental Research Program in the fields of Natural Sciences (KT 04) for the support in this study. We are indebted to Prof. Fang Zong-jie, Dr. Wang Yi

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(Nanjing Inst.of Geol. & Palaeont.) for identifying the Bivalves and the spores and their discussions on the age of the t'ossil- bearing beds. We also thank to our friend Dr. Ph. Janvier (Institut de Pale'ontologie, Paris) for the successful collaboration and discussion o tth e age of the fossil-bearing beds of both Do Son and Dong Tho Formations. The authors are indebted to Dr. Vu Ngoc Tu (Vietnam National University, Ha Noi) for his help in the redaction of the English of this paper.

REFERENCES

CAI CHONG-YANG & LI XING-XIJE, 1082. Subdivision and correlation o f continental Devonian strata in China. In: Slratigraphical correlations in China. 10 - 123. Nanjing Inst. Geol.& Palaeont. Science Press. Beijing (in Chinese).

CAI CHONG-YANG & LI XING-XUE, 1994. A review o f Silurian and Devonian microfloras in China, Palaeontologia Cathayana.6: 167 - 214.

DOVJIKOV A.E., BIJI l’lHJ MY, IVANOV G.V., IZOKH E.P., JAMOIDA A.I., LE DINH innJ, MAREICHEV AM ., NGUYEN TIJONG TRI. NGUYEN VAN CHIKN, PHAM DINH LONG, PHAM VAN QUANC’., TRAN DIJC LI JONG, VASSILHVSKAIA E. D. Geologia Severnogo Yielnama (Geoloqv o f the North o f Viet Nam). Tổng cuc Đia chất . Hâ Nời. 1065:1 - 668 (in Russian)Địa chấ Miền Bắc Viet Nam. Klioa Học và Kỹ thuật. Hà Nôi. 1971:1 - 584 (in Vietnamese).

IXJONG XIJAN HAO (Edit ). Hoá thạch đạc trưng ở Miền Bắc, Việt Nam (Characteristic fossils in the North o f Viet Nam). Khoa họcc và Kỹ thuật. Hà Nội: 1 - 600, including 123 plates (in Vietnamese with English Summary)

LU LI-CHAN(Ì^ 1980. Devonian miospores from the Longhuashan section in Zhangvi o f Yunnan and their strati graphic significance. Mem. Nanjing Inst. (ieoi. & Palaeont. Acad. Sin. 14: 1 - 62 (in C’hinese with English Summary)

U J LI-CHANG, 1988. Middle mioflora from Haikou Formation at Shijapo in Jangyi o f Yunnan, China. Mem. Nanjing Inst. Geol. & Palaeont. Acad. Sin. 24:10-68(in Chinese with English Summary).

McGREGOR D.C. & PLAYFORD G. 1992. Canadian and Autralian Devonian spores: Zonation and correlation. Geol. Surv. Canada Bull. 438: 1 - 125.

RICHARDSON J.B. & McGREGOR D.C. 1986. Silurian and Devonian spore zones o f the Old Red Sandstone Continent and adjacent regions. Geol. Surv. Canada Bull. 364: 1 - 79.

TA HOA PHI JONG 1994. New discoveries o f pelagic fossils from Devoniandeposits o f Dong Van Area(Ha Giang Provine. Viet Nam). Proceed. Intern. Symp. Stratigrphic Correlation ot Southeast Asia.Bangkok: 62-68.

TONG-DZIJY THANH 1993. Majorfeatures o f Devonian stratigraphy in Viet Nam with remarks on paleobiogegraphy. Journ. Geol. (Geol Surv. Viet Nam). Ser.B 1-2: 3 - 18.

TONG-DZIJY THANH (Edit.). 1988.Strtigrafia / tselenteraty Devona Vietnama (Devonian Stratigraphy and Coelenterata o f Viet Nam).Stratigraphy: 1-183.Nauka. Siberian Branch Novosibirsk, (in Russian)

TONG-DZIJY THANH 1993. Majorfeatures o f Devonian stratigraphy in Viet Nani with remarks on paleobiogegraphy. Journ. Geol. (Geol Surv. Viet Nam). -Ser.B 1-2: 3 - 18.

TONG-DZIJY THANH & JANVIER Ph. 1990. l.es Vertebres du Devonien infe'rieur du Bac Bo oriental (Province de Bac Thai et Lang Son, Viet Nam). Bull. Mus. Nat. Hist. nat. Paris. C. 12 : 143 - 233.

TONG-DZIJY THANH & JANVIER Ph. & DOAN NHAT TRUONG 1994. Premiere decouverte d'un Placoderme (Vertebrata) dans le Devonien du bloc Indochinois (Trung Bo. Viet Nam Central). Bull. Mus. Nat. Hist. nat. Paris. C. 16; 259 - 279.

TONG-DZIJY THANH & JANVIER PH. & DOAN NHAT TRUONG and BRADY S. 1994b.New Vertebrate remains assicated with Eurvpterids from the Do Son Formation, Viet

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feiam. Jour, of Geology (Grol. Surv. Viet Nam)Ser.B: 1 - 11 .

TONG-DZUY THANH, JANVIER PH., TA HOA PHUONG, DOAN NHAT TRUONG. Fish provides evidence for close contact between the Indochina and South China blocks in Middle Devonian times (in press).

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EXPLANATIO N OF PLATE I

(Devonian Flora of Viet Nam)

Figs. 1,2.Zosterophyllum ? sp.(X 1) Two axes with H-type branching. Locality: Ban Keo Mieng, south slope of Phu Puoc Mt. Muong Xen district. Nghe An Province (specimen 26318, Dovjikov et al. 1965). Horizon: Lower Member of Tay Trang Complex (Former Huoi Nhi Formation). Lower Devonian.

Figs.3,3a,4. Zosterophyllum sp. Fig.3(X 1) showing the upper part of a spike. Fig. 3a (X 3):enlargement of the same specimen. Fig.4 ( XI ) showing the lower part of the spike. Locality: about 3.5km southeastward from Ban Keo Mieng, Muong Xen District, Nghe An Provine (specimen 26320, Dovjikov et al. 1965).Horizon: see Fig. 1 and 2.

( The photos of Fig. 1-4 are offered by the Laboratory of Paleontology & Stratigraphy. Institute of Geology and Mineral Resources, Hanoi).

Figs.5,5a,5b .Protolepidodendron sp. and Bergeria (Lepidodendropsis sp.). Fig. 5 ( X 1) showing a stem of Protolepidodendron sp., indicated by the letter a at the left side of the figure and a stem of Bergeria (Lepidodendropsis sp.), indicated by the letter b at the right side of the figure. Figs 5a,5b(X 3):partial enlargement of two stems. Locality: Hoi Da stream, near Minh Le railway bridge, Quang Binh Province. Horizon: Dong Tho Formation (Givetian).

Figs. 6,6a,7. Bergeria (Lepidodendropsis sp.). Fig.6 ( XI ) showing the stem in positive view. Fig. 6a (X 3): partial enlargement of Fig.6. Fig.7 (X 1) showing the same stem in lateral view. Locality and Horizon: the same as of Fig.5.

Fig.8. Bergeria (Lepidodendropsis sp.) (X 0.64) showing the stem with dichotomous branching. Locality, Horizon: see Fig 5.

Figs.9,9a. Taeniocrada ? sp. Fig.9 (X 1) showing the stem with a central vascular bundle. Fig.9a (X 2): partial enlargement of Fig.9. Locality: Bo Hieng village. Song Da downstream (Northwest of Viet Nam). Horizon: Bo Hieng Formation, Upper Silurian.

VU KHUC (Edit.) 1984. Hoẩ thạch Đặc trưng ở Miền Nam Việt Nam (Characteristic fossils o f the South ơ f Viet Nam). Khoa học và Kỹ thuật. Hà Nội: 1-286, including 73 plates (in Vietnamese with English Summary).

VU KHUC & BUI PHU MY (Edit.) 1989. Địa chất Việt Nam. Tập I : Địa tầng (Geology o f Viet Nam. Vol. I: Stratigraphy. Khoa học và Kỹ thuật. Hà Nội: 1 - 378 (in Vietnamese).

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Plate I

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