Revisiting the “Irtish tectonic belt”: Implications for the Paleozoic tectonic evolution of the...

Journal of Asian Earth Sciences 52 (2012) 117–133

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Journal of Asian Earth Sciences

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Revisiting the ‘‘Irtish tectonic belt’’: Implications for the Paleozoic tectonicevolution of the Altai orogen

Chuan-Lin Zhang a,⇑, M. Santosh b,c, Hai-Bo Zou d, Yi-Gang Xu e, Gang Zhou f, Yong-Guan Dong a,Ru-Fu Ding a, Hong-Yan Wang a

a Nanjing Institute of Geology and Mineral Resources, Chinese Geology Survey, Nanjing 210016, PR Chinab Division of Interdisciplinary Science, Faculty of Science, Kochi University, Kochi 780-8520, Japanc Geoscience Frontiers, China University of Geosciences Beijing, 29 Xueyuan Road, Beijing 100083, PR Chinad Department of Geology and Geography, Auburn University, Auburn, AL 36849-5305, USAe Key Laboratory of Isotope Geochronology and Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR Chinaf Xinjiang Bureau of Geology and Mineral Resources, Urumqi 830000, PR China

a r t i c l e i n f o a b s t r a c t

Article history:Received 27 October 2011Received in revised form 11 February 2012Accepted 16 February 2012Available online 24 March 2012

Keywords:Irtish tectonic beltGeochronologyTectonic evolutionPermian mantle plume

1367-9120/$ - see front matter � 2012 Elsevier Ltd. Ahttp://dx.doi.org/10.1016/j.jseaes.2012.02.016

⇑ Corresponding author. Tel.: +86 25 84897936; faxE-mail address: [email protected] (C.-L. Zh

The Irtish tectonic belt is one of the most important suture zones in the Central Asian Orogenic Belt(CAOB). The various models invoked to explain the tectonic evolution of this belt in relation to Paleozoiccontinental growth include: (1) syn-subduction strike-slip duplication of a single long-lived arc, and (2)collision of many arcs and micro-continents. Here we report new results from detailed field studies, geo-chemistry and zircon U–Pb geochronology on the major rock units along the Irtish belt both in Kazakh-stan and in the Chinese Altay. Our new results, together with information from published data, suggestthat the Altai-Mongolia terrain witnessed several episodes of subduction. The Junggar terrain, whichformed by multiple collisions of intra-oceanic arcs, seamounts and ophiolite suites prior to 330 Ma, sub-sequently amalgamated with the Altai-Mongolia terrain at around 320 Ma along the Irtish suture zone.Following the clockwise rotation of the Siberian craton and the N-directed movement of the Junggar ter-rain, the sinistral strike-slip motion along the Irtish suture zone resulted in ductile shearing, partial melt-ing of the crustal material, and the formation of mylonites, syn-tectonic migmatite and gneissic granites.The sinistral strike-slip deformation of the Irtish suture zone culminated at ca. 275 Ma. The diverse 275–250 Ma magmatism (mafic–ultramafic complexes, bimodal intrusives, mafic and silicic dykes, A-type andI-A-type granites) is related to magma pulses generated by the Permian Tarim mantle plume. Our modelof multiple episodes of subduction below the Altai arc is different from previous models and proposesthat the subduction continued until Triassic with the Permian subduction under the Altai arc and a latePermian large-scale south-directed thrusting.

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1. Introduction

The Altai orogen (He et al., 1990, 1994) of the Central Asian Oro-genic Belt (CAOB) (Carroll et al., 1995; Ruzhentsev and Mossakov-skiy, 1996; Jahn et al., 2000, 2004; Dobretsov et al., 2003) is one ofthe key areas to evaluate the history of accretionary orogeny incentral Asia. Although many studies have been carried out in theAltai orogen (Dobretsov, 2003; Dobretsov et al., 2003, 2004; Xuet al., 2003; Niu et al., 2006; Li, 2006; Xiao et al., 2004, 2008a,2008b, 2009b; Briggs et al., 2007, 2009; Ao et al., 2010; Glorieet al., 2011; Lei et al., 2011), the tectonic history of this region con-tinues to be a topic of debate, particularly focusing on its accretion-ary history and continental growth (Jahn et al., 2004, 2009). The

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two contrasting models for the growth of the Altai orogen arethe duplication of a long-lived, single arc subduction (Sengöret al., 1993) versus multiple arc subduction systems (Mossakovskyet al., 1993; Buslov et al., 2001, 2003, 2004; Xiao et al., 2004; Briggset al., 2007; Windley et al., 2007; Rojas-Agramonte et al., 2011).Studies conducted in the recent years have suggested that a Perm-ian Large Igneous Province, the ‘Tarim LIP’ as termed by Borisenkoet al. (2006, also known as Bachu LIP or Tarim-Bachu LIP, e.g.,Zhang et al., 2008a,b, 2010a; Pirajno et al., 2009), could have signif-icantly contributed to the tectonic evolution and continentalgrowth in the Altai orogen or even to the whole CAOB (Zhouet al., 2004, 2009b; Zhang et al., 2010a,b). Thus, it is important toevaluate the processes of oceanic subduction, arc-collision, oceanclosure and subsequent strike-slip faulting and mantle plumedynamics in order to better constrain the tectonic architecture ofthe Altai orogen.

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118 C.-L. Zhang et al. / Journal of Asian Earth Sciences 52 (2012) 117–133

The Irtish suture zone (also known as Irtysh, Erqis, Irtishi, Ertix),or Irtish tectonic belt, witnessed almost the whole evolution his-tory of the Altai orogen and is the key to understand the complexevolutionary history of the orogen. In this study, we present theresults of our detailed field observations and systematic zirconU–Pb geochronology along the Irtish belt, both in northernXinjiang domain of China (the southeastern segment) and theUst-Kamenogorsk domain of Kazakhstan (the northwestern seg-ment). Combined with geochemical data, we address the tectonichistory of the Irtish belt with a specific focus on the history fromarc-collision through sinistral strike-slip to plume-related regionalextension.

2. Regional tectonic framework

The tectonic framework of the study area can be divided intothree major units: the Altai orogenic belt (including Altai-Mongo-lian terrain and Rudny Altai terrain, Buslov et al., 2003), the Irtishsuture zone, and the Junggar terrain (Carroll et al., 1990, 1995; Xiaoet al., 2009b, 2011; Yin et al., 2010; Zhang et al., 2011) (Fig. 1). TheChinese segment of the Altai-Mongolian terrain has been regardedas a Precambrian block based on the presence of Sinian fossils, Pre-cambrian Nd model ages of some of the gneiss granites and the Ar-chaean to Neoproterozoic zircon xenocrysts (Li and Poliyangsiji,2001; Hu et al., 2002; Wang et al., 2006, 2009). In recent years,high-resolution zircon ages were reported from some of thehigh-grade metamorphic rocks in this region (Hu et al., 2006; Zhouet al., 2007; Yuan et al., 2007a), although the timings and tectonicimplications remain controversial. In order to address this enigma,in the present study, we chose some of the representative meta-morphic units including gneisses and schist to the north and alongthe Irtish belt for detailed petrographic and geochronologicalstudy. In the case of the Junggar terrain, several recent studies haveunequivocally established that it was formed by multiple accre-tions of seamounts, intra-ocean arc, ophiolite fragments, subduc-tion complex from middle Cambrian to Carboniferous with nocompelling evidence for a Precambrian basement (Carroll et al.,1995; Hu and Wei, 2003; Chen and Jahn, 2004; Han et al., 2006;Niu et al., 2006; Jahn et al., 2004; Xiao et al., 2004, 2009a,b; Zhang

Fig. 1. Regional geologic map of the Altai orogenic belt and its neighboring regions, simp

et al., 2010a). Thus, it is reasonable to deduce that the Junggar ter-rain was a juvenile segment formed no later than 320 Ma because(1) all the precisely dated ophiolites in eastern and western Jung-gar are older than ca. 330 Ma; and (2) all the 320–250 Ma granitesand mafic dykes in this terrain exhibit typical intraplate or post-collisional geochemical signatures (Han et al., 1997; Chen and Jahn,2004; Wang et al., 2005; Tong et al., 2006; Tang et al., 2007; Xiaoet al., 2009b; Zhou et al., 2009a; Yuan et al., 2010). The Irtish belthas been regarded as the final zone of suturing between the Al-tai-Mongolian terrain and the Junggar terrain in China in the east,and those terrains which were detached from the Kazakhstan blockto the west (Fig. 1) (Buslov et al., 2004). The belt has long beeninterpreted as a large-scale strike-slip fault, but the componentsof the unit and nature of the strike-slip faulting, as well as theirrelationship with the adjacent tectonic units, remain unclear (Xiaoet al., 2009a). Particularly, the several ophiolitic complexes re-ported in various studies such as those of Bai and Zhou (1989,1991), Niu et al. (2006) and Xiao et al. (2009b) need to beconfirmed.

Further east, Cunningham et al. (1996), Cunningham (2005)correlated the Irtish fault from China with the Bulgan obliquethrust fault, which places the high-grade gneisses and schistsagainst granite, greenschist, and quartzite in western Mongolia.Badarch et al. (2002) correlated the Irtish fault with a suture zonemarked by an east-trending ophiolite belt in south-central Mongo-lia and this belt is interpreted as the locus of a back arc basin thatwas closed by the collision between a Devonian arc along the Mon-golian–China border to the south and the Siberian craton and itsfringing arc to the north.

3. Field observations and sample collections

3.1. Ust-Kamenogorsk

The segment of the Irtish belt at Ust-Kamenogorsk separates theKalba-Narym and Rudny Altai terrains (Buslov et al., 2004) (Fig. 2).The strike-slip zone generally consists of tectonic sheets of stronglymetamorphosed rocks that have undergone partial melting.According to Melnikov et al. (1997, 1998), the strike-slip zone is

lified from Buslov et al. (2004). Locations of Figs. 2, 5–7 and 9 are shown with box.

Fig. 2. A geological sketch of the Irtish strike-slip zone at Ust-Kamenogorsk in Kazakhstan. Previous geochronological data (gray box, after Buslov et al. (2004)) and newgeochronological data obtained in this study (blank box) are shown. Fig. 3 (geological section) is also shown.

C.-L. Zhang et al. / Journal of Asian Earth Sciences 52 (2012) 117–133 119

dominated by sinistral strike-slip faults of variable scale. The dom-inant structure of the zone is characterized by NW–SE orientationwith steep dips to the NE.

Field observations at Ust-Kamenogorsk show that the Rudny-Altaid terrane to the north of the Irtish belt consists of terrigenousdetrital turbidite with flysch structure, including greenschist-faciesmetamorphic sandstone, siltstone, phyllite and slate. Their petro-graphic features, strong-deformation and the green-schist faciesmetamorphism are markedly identical to the Habahe Group inthe northern belt of the Chinese Altay. Based on U–Pb age datafrom detrital zircons, Yuan et al. (2007a) constrained the deposi-tional time to be Mid-Ordovician to Early Devonian, with the ter-rigenous materials of the Habahe Group dominated by earlyPaleozoic magmatic sources containing a small proportion of Pre-cambrian components. The age data and morphological character-istics of the detrital zircons, in combination with the geochemicaldata from the fine-grained sedimentary rocks (Long et al., 2008),suggest that the terrigenous detritals of the Habahe Group weremost likely derived from the Early Paleozoic orogenic belt in GornyAltaid immediately to the north of the Altai-Mongolian terrain. Tothe south of Irtish belt at Ust-Kamenogorsk, a Mid-Devonian toEarly-Carboniferous island arc complex is exposed (Buslov et al.,2004). The rocks in this belt experienced greenschist facies meta-morphism and were subsequently intruded by Permian batholiths(Rorarash et al., 1982; Vladimirov et al., 1997; Travin et al., 2001).The rocks within the Irtish belt at the Ust’-Kamenogorsk segmentinclude biotite schist, biotite plagioclase gneiss, migmatite, gneis-sic granites and granodiorite (Fig. 3). The outcrops of biotite schist(or gneiss) mostly occur in the southern part whereas the gneissicgranite and migmatite occur towards the north. However, at sev-eral localities, both the rocks are inter-layered with a gneissic fab-ric (Fig. 3). Ductile shear belts occur between the different rocktypes and especially within the migmatite (Fig. 4a and b). A NW–SE-striking foliation with a sub-horizontal lineation is developedthroughout the area. Asymmetric boudinage (mostly Z-type), theangle between S and C foliations and mineral stretching lineations,indicate sinistral ductile shear, as also indicated by fabrics in the

migmatites and gneissic granites (Fig. 4a and c). The small grano-diorite pluton that intrudes into the biotite schist and migmatitesshows block structure and no deformation (Fig. 4d). Our fieldobservations suggest that the migmatite and the gneissic graniteare products of anatectic melting of the biotite (-plagioclase) schist(or gneiss) related to an important tectonothermal event. Thegranodiorite might represent the latest phase of this event.

From the Irtish belt at Ust-Kamenogorsk, we used sample08TK01 (82�4201600E, 50�0101400N) from the biotite plagioclasegneiss, sample 08TK15 from the gneiss granite (82�4201800E,50�0101600N) and sample 08TK16 (82�4201800E, 50�0101800N) fromthe un-deformed granodiorite for detailed studies.

3.2. Geological section to north of Buerjin

In the low hills north of Buerjin, the major rocks consist of high-grade metamorphic gneiss, schist, anatectic granitic lens and gneis-sic granites, locally known as the Kemuqi Group (Xinjiang BGMR,1993). On several outcrops, as the modal content of biotite and gar-net decreases and that of quartz and feldspar increases, the gneissshows a gradual transformation to gneissic granite. The foliationsof the gneiss, schist and the granites are consistent with a NE dipat moderate angles. At the southern side, the gneiss is thrust onthe Devonian Altai Formation composed of metamorphosed vol-cano-sedimentary rocks (Fig. 5). Xiao et al. (2009a) suggested anophiolitic mélange striking 10–15 km in NW direction and of sev-eral kilometers in width, mainly consisting of ultramafic–maficlens, pillow basalts and cherts, occurring along the highway fromBuerjin to Kanas, with the different rock units repeated by thrustsseveral times along the section. However, our field observation inthis section and the 1:50,000 geological mapping in this area didnot reveal any ultramafic rocks. On the contrary, several amphibo-lite lenses and stripes were found which occur in close associationwith the garnet-biotite schist, garnet-bearing plagioclase gneissand the gneissic granite (see detailed discussion in Dong et al.(2002)). Along this section, most of the rocks show high-grademetamorphism and intense deformation. We therefore consider

Fig. 3. Geological cross-section of the schist, gneiss, migmatite and gneissic granites in the Irtish belt at the Ust-Kamenogosk, Kazakhstan. Sample locations are also shown.


that the so-called ophiolite complex in this area requires furtherevaluation. A representative sample (08AL11, 87�0804300,48�0905700) was collected from the biotite-plagioclase gneiss forU–Pb dating.

3.3. Kekesentao area

The ultramafic–mafic complex in Kekesentao area has been con-sidered to be a late Palaeozoic ophiolite by many geologists (e.g., Heet al., 1990, 1994, 2001; Xu et al., 2003; Niu et al., 2006; Xiao et al.,2008a,b, 2009a,b). Niu et al. (1999, 2006) suggested that the rocks inthe Kekesentao area are similar to those of Suoerkuduke andSaerbulake in that they occur as melange or olistostrome deposits.Nevertheless, our 1:50,000 mapping (with ca. 100 m spacing forthe ultramafic–mafic complex) and investigations in several geolog-ical sections indicate that the ultramafic–mafic complex in Keke-sentao is mostly represented by intrusive rocks rather than atypical ophiolite complex (Fig. 6A and B). Two major ultramafic–mafic complexes are exposed in the Kekesentao area in the westerncomplex (Fig. 6A) and the eastern complex (Fig. 6B). The rock stratain Kekesentao include middle Devonian Yundoukala Formation,Mid-Carboniferous Nalinkala Formation and Mid- to Upper-Carbon-iferous Jimunai Formation. The dominant rocks in the lower part ofthe Yundoukala Formation are metamorphosed fine-grained clasticrocks (including fine-grained sandstone, siltstone, argillaceous silt-stone), and some volcanic breccia, crystal tuff and marble beds of 1–5 m thick are interlayered with clastic rocks. The upper part of theYundoukala Formation is mainly composed of slightly metamor-phosed clastic rocks and no volcanic rocks are observed. The Nalin-kala Formation, unconformably lying on the Yundoukala Formation,is mainly composed of immature clastic rocks interlayered withminor rhyolite and basalt lacking of pillow structure. The JimunaiFormation unconformably overlies the Nalinkala Formation andexhibits features typical of terrigenous deposits. The lower part ismainly composed of red volcanic breccia and (crystal-bearing) tuffinterlayered with minor thin layers of green basalt (individual layeris less than 1 meter thick), whereas the upper part is composed ofvaried-colored clastic rocks and several layers of conglomerate,exhibiting the characteristics of continental sedimentary facies.

Field observations show that both the western and eastern ultra-mafic–mafic complexes intrude the middle Devonian YudoukalaFormation and are in turn intruded by potassic granite (Fig. 6). Therock types within the ultramafic–mafic complex include peridotite(�10% of the outcrop), olivine-bearing gabbro, gabbro (�80%) anddiorite (less than 10%) (Fig. 10A). The gabbro facies mostly occursat the center of the complex and the peridotite is exposed alongthe margin. Diorite matrix was observed at the top of the gabbro fa-cies, indicating that the diorite crystallized from the mafic magma.

Four representative samples from the Kekesentao area were se-lected for geochronological studies. Sample 09AL25 (47�3401200N,

86�4302800E) was collected from the pegmatoid gabbro from theultramafic–mafic complex in the western pluton, sample08TW01 (47�3001500N, 86�5204500E) comes from a coarse gabbro inthe eastern part pluton, sample TW02 (47�3201000N, 86�4400700E)is from the granodiorite pluton and 08TW03 (47�3404700N,86�4203600E) represents the potassic granite pluton which intrudesthe ultramafic–mafic complex (Fig. 6). In addition, eleven sampleswere collected from the diverse rock types in Kekesentao ultra-mafic–mafic complex for geochemical analyses.

3.4. Mayinebo belt and the northwestern part of Fuyun area

The Mayinebo segment is located at the southeastern part of theIrtish belt (Fig. 1), and shows a width ranging from ca. 5 to 20 km(locally known as Mayinebo fault). Several geological units wereidentified here based on our field observation and regional geolog-ical mapping (Figs. 1 and 7), as summarized below.

(1) The gneissic rocks are mostly exposed along the shear zoneand the main rock types include plagioclase gneiss, biotite schist,garnet-bearing schist (or gneiss), gneissic granites and somestrongly deformed silicic dykes or lens. Earlier studies assignedPrecambrian ages to the gneiss/schist based on imprecise Sm–Ndisochron ages and some Precambrian microfossils (Hu et al.,2002). Recently, Hu et al. (2006) reported an age of ca. 283 Ma fromSHRIMP U–Pb age on zircons from the gneiss/schist. (2) The gneis-sic granites is in contact with the gneiss/schist along a deep NEdipping fault, and the major minerals in this rock include biotite(5–15%), albite-oligoclase, microcline (50–60) and quartz (35–45%). Zircon SHRIMP U–Pb ages indicate that the protoliths of theserocks crystallized at ca. 284 Ma (Zhou et al., 2007) and their geo-chemical compositions show potassic (K2O 3–6%) and A-type char-acteristics (most samples have Zr higher than 400 ppm) (Zhouet al., 2007). (3) The gabbro stocks or dykes intrude the ca.284 Ma gneissic granites and the Sinian Fuyu Group to north of Irt-ish belt crystallized at ca. 272 Ma with geochemical characteristicstypical of intraplate origin (Zhang et al., 2010a). To the south ofIrtish belt, Mid-Devonian to Early Carboniferous volcanic rocksare widely distributed and their compositions and geochemicaldata show that they were formed in an arc setting (Xu et al.,2001; Zhang et al., 2008a). Several granite plutons dated as 280–334 Ma intruded into the strata (Zhou et al., 2007).

Along the Mayinebo belt, ductile shear deformation affected thehigh-grade metamorphic rocks and the gneissic granites, produc-ing mylonitic schist, gneisses and mylonitized granites, showingS–C fabric structure (Fig. 8C, E and F), asymmetric folding(Fig. 8A and B) and augen structure (Fig. 8D). The shear zone isdominated by steeply NE dipping penetrative mylonitic foliationwith a gently plunging sub-horizontal mineral stretching lineation.Although the foliation strike and lineation trend vary slightly alongthe shear zone, the angle between S and C foliations, as well as the

Fig. 4. Representative field photos of the different rock types along the Irtish belt atUst-Kamenogorsk, Kazkhstan. (A) and (B) Ductile deformation in the gneiss,anatexis of the gneiss, and recumbent folding indicating sinistral shear. In (A) thecamera lens oriented to the horizontal surface and the latitude of the foliation is42�\65� (dip direction \dip angle). (C) Gneissic granites with is the gneissosityconsistent with the foliation of the schist and gneiss. (D) Granodiorite plutonintrudes into the migmatites and sharply cutting the foliation.


lineation plunge and the asymmetric folds indicate a sinistral shear(Fig. 8C and F), similar to the observations at Ust-Kamenogorsk.Though the gneissic granites appear strongly mylonized, in thinsections the rocks preserve relatively undeformed mineral assem-blages, as discussed in a later section.

Immediately to the northwest of Fuyun County, Briggs et al.(2007, 2009) documented a series of imbricated thrust faults(Fig. 9). The Irtish thrust in this area is consistent with the Mayin-ebo belt to the southeast which is truncated by the Fuyun dextralstrike-slip fault. In this tectonic belt, intensive mylonitization andmigmatisation are displayed by the gneiss/schist similar to the fea-tures in the Mayinebo area. A granite dyke swarm, striking north-east, sharply cut the foliation of the gneiss/schist (Fig. 10B). Thedykes are very fresh and undeformed, obviously emplaced afterthe ductile shear deformation. These dykes could constrain thelower limit of the time of the ductile sinistral strike-slip of the Irt-ish belt.

For this study, three representative samples were collected forzircon U–Pb dating from the mylonitized gneiss at Mayinebo(Fig. 7, 04TW3, 46�3502100N, 90�0605500E), the granite dykes(08AL18, 47�0202200N, 89�2001500E) and the migmatite (0410TW3,47�0602700N, 89�2803800E).

4. Analytical methods

Mineral separation was carried out using conventional mag-netic and density techniques to concentrate the non-magnetic,heavy fractions. The zircon grains were then hand-picked under abinocular microscope. The morphology and internal structure ofthe zircons were documented with transmitted and reflected lightphotomicrographs and cathodoluminescence (CL) images (Back-scattered Electron Imaging, BSE in short, is also used for severalsamples). Sample 04TW3 and 0410TW3 were analyzed using theSHRIMP ion microprobe at the Beijing SHRIMP Centre, ChineseAcademy of Geology, using the standard operating conditions (Wil-liams, 1998). U–Th–Pb ratios were determined relative to theTEMORA standard zircon, and the absolute abundances of U andTh relative to the SL13 standard zircon. Software SQUID 1.0 andISOPLOT (Ludwig, 1999, 2001) were used for data processing. Theweighted mean ages are quoted at 95% confidence level. All othersamples were analyzed using LA-ICPMS U–Pb dating method bothat the Tianjing Institute of Geology and Mineral Resources andNorthwest University of China. The detailed procedures of samplepreparation and the analytical technique have been documented inYuan et al. (2003). The data processing is similar with that for theSHRIMP analysis. The analytical results are listed in SupplementaryTable 1.

Major-element oxides were determined using a Rigaku ZSX100eX-ray fluorescence (XRF) spectrometer on fused glass beads, andtrace elements were analyzed using a PQ2 Turbo ICP-MS, both atthe Guangzhou Institute of Geochemistry of the Chinese Academyof Sciences, following analytical procedures similar to those re-ported in Li et al. (2006). The analytical error is between 1% and5%. The analytical results of major and trace elements are listedin Supplementary Table 2.

5. Analytical results

5.1. Ages of the rocks from Ust-Kamenogorsk

In this study, U–Pb zircon ages were obtained on three samples(08TK01, 08TK15 and 08TK16) from Ust-Kamenogorsk.

Most zircons from the biotite-plagioclase gneiss (sample08TK01) are transparent, colorless and some are slightly pinkish,ranging from 100 lm to 150 lm in length and with a length to

Fig. 5. Geological map (A) and geological cross-section (B) along the northern margin of the Irtish belt at Buerjin county. Simplified from the 1:200,000 geological map(Xinjiang BGMR, 1993). The pre-Devonian gneiss is thrust onto the Devonian Altai Formation, which is composed by a suite of volcano-sedimentary rocks.


width ratio of 2–3. The majority of zircons are euhedral but someshow variable degrees of roundness resulting from sedimentarytransportation. The zircons are dominantly of magmatic origin asillustrated by their oscillatory zoning in CL images but a few zir-cons exhibit no zoning and have very bright CL images. These zir-cons without zoning show ellipsoidal shapes typical ofmetamorphic origin. Thin and bright rims (less than 10 lm) wereobserved in most magmatic zircons suggesting metamorphic over-growth. Twenty-five analyses were conducted on 25 zircons fromsample 08TK01. Among these, four spots (1.1, 7.1, 9.1, 10.1) onthe zircons with bright CL images yield younger 206Pb/238U ageswith low Th/U ratios (0.07–0.20), suggesting a metamorphic origin.The other 21 analyses show Th = 26–382 ppm, U = 41–487 ppmand Th/U ratios ranging from 0.2 to 1.2. They yield 206U/238U agesranging from 420 Ma to 831 Ma. The relatively euhedral zircons ofmagmatic origin yield 206Pb/238U ages ranging from 420 to 460 Ma.In thin section, this rock contains plagioclase grains of probablevolcanic origin. The six older ages (>650 Ma) were obtained fromthe ellipsoidal grains but with significant oscillatory zoning. Obvi-ously, the grains are of detrital origin. Based on the above data, wesuggest that the protoliths of the gneisses from Ust’-Kamenogorskare early Palaeozoic and were metamorphosed at ca. 380–400 Ma(Fig. 11A).

Zircons from sample 08TK15 are euhedral and range from80 lm to 150 lm in length, with a length to width ratio of�2. Theyare transparent and colorless, and only a few zircon grains containinherited cores. Euhedral concentric zoning is common, suggestinga magmatic origin. Twenty analyses were obtained on 20 grains(Supplementary Table 1). U concentrations range from 27 to258 ppm, Th from 53 to 373 ppm and Th/U ratios vary within the

range of 0.20–1.12 (mostly between 0.4 and 0.8). The 20 analysesagree within errors and yield a weighted mean 206Pb/238U age of281 ± 1 Ma (MSWD = 1.1) (Fig. 11B). This age is interpreted as thecrystallization age of the gneiss granite.

Most zircons from sample 08TK16 are euhedral, range from 80to 150 lm in length and a few are ellipsoidal in form. In CL images,two zircon grains display relatively dark color and their analyticaldata show the highest U and Th contents with relatively youngerages (spots 8.1 and 12.1). These features suggest possible recrystal-lization and variable radiogenic Pb loss. Two spots on the ellipsoi-dal zircons yield relatively older 206Pb/238U ages (�320 Ma), andare likely to be xenocrysts. The other 12 analyses have U contentsof 30–126 ppm, Th of 81–346 ppm and Th/U ratios ranging from0.22 to 0.39. Among these, eight analyses yield relatively concor-dant 206Pb/238U ages with a weighted mean age of 252.4 ± 2.6 Mathat might represent the crystallization age of the diorite pluton(Fig. 11C).

5.2. Ages of the gneiss from north of Buerjin

U–Th ages were obtained on zircons from one biotite gneiss(08AL11) from the north of Buerjin. Most zircons from this sam-ple are transparent, colorless (with a few grains showing pinkishcolor) and elongate in shape (100–150 lm and with length/widthratios of 2–3:1). The majority of zircons are euhedral, but somewith variable degrees of roundness are also present, suggestingsedimentary transportation. The zircons are dominantly of mag-matic origin as illustrated by their oscillatory zoning in CLimages, but a few grains exhibit no zoning and have bright CLimages. These zircons are ellipsoidal in shape and appear to be

Fig. 6. Geological map of the Kekesentao ultramafic–mafic complex (A, westernpluton; B, eastern pluton). The two plutons consist of dunite, olivine-bearinggabbro, gabbro and minor diorite. The ultramafic complex intrudes into the mid-Devonian volcano-sedimentary strata (Yundoukala Formation) and are in turnintruded by potassic granites (legends of the A and B are put together).


of metamorphic origin. Fifty-four analyses were carried on 54 zir-con grains and the results are listed in Supplementary Table 1.

Fig. 7. Geological map of the Mayinebo area at the eastern segment of the Irtish belt. Reviin this area are also shown (ages shown in the blank box are from Zhou et al., 2007; Zh

Among these, six spots (8.1, 25.1, 43.1, 46.1, 48.1, 49.1, 50.1)have relatively low Th contents (21–82 ppm), variable Th/U ratios(0.07–0.83) and 206Pb/238U ages in the range of 419–453 Ma.Based on their relatively bright CL images, we infer a metamor-phic origin. The second group shows 206Pb/238U ages of 460–470 Ma (spots 3.1, 12.1, 19.1, 36.1, 38.1, 41.1, 44.1, 47.1, 51.1,54.1) and most of them have high Th/U ratios except for spot47.1 (Th/U = 0.13, and a light CL image). These grains are mostlikely to be of magmatic origin. Nevertheless, some zircons fromthis group have euhedral shapes that are very different from thedetrital zircons. More detailed study is needed to evaluatewhether or not these zircons were crystallized during theregional anatexis (such as the migmatisation observed at severaloutcrops) or derived from the denudation of the poorly sortedclastic sources. The other 36 analyses show variable older206Pb/238U ages ranging from 485 Ma to 2528 Ma and most ofthem yield Neoproterozoic to Cambrian ages (Fig. 12), indicatingthat the clastics of the gneiss were mainly derived from Neopro-terozoic to Cambrian sources. In summary, the age data suggestthat the zircons in these metasedimentary gneisses were derivedfrom late Cambrian to early Ordovician sources and that theserocks were possibly metamorphosed at ca. 450–420 Ma. Thisinterpretation is also consistent with the fact that the late Ordo-vician rock unconformably overlies the gneiss (Xinjiang BGMR,1993).

5.3. Ages of the rocks in Kekesentao area

Zircon U–Pb ages from four samples (09AL25, 08TW01,08TW02, and 08TW03) were obtained in this study from the Keke-sentao area.

The zircons in the coarse-grained plagioclase-rich gabbro sam-ple 09AL25 are transparent and colorless and have lengths up to300 lm. In CL images, with typical banded structure in most ofthe crystals, indicating a magmatic origin. No core-rim structurehas been observed in the CL images. Twenty-three analyses wereperformed on 23 zircon grains of magmatic origin. The analysesshow variable abundance of U (26 ppm to 142 ppm) and Th(50 ppm to 221 ppm) and Th/U ratios of 0.44–0.83. Among these,

sed after the 1:50,000 mapping data (Zhou et al., 2007). The geochronological resultsang et al., 2010a).

Fig. 8. Field photos and thin section photos showing the sinistral ductile shear along the Irtish belt at the Mayinebo area. (A) and (B): Z-type folding indicating sinistral strike-slip (attitude of the foliations in A and B are 72�\68� and 67�\63�, respectively). (C) Domino effect of the biotite during sinistral shearing (attitude of the foliation of theoriented specimen for this thin section is 68�\71�). (D) Sheared plagioclase eyeball (attitude of the foliation of the oriented specimen for this thin section is 68�\71�). (E) and(F) Well-defined S–C fabrics in the mylonites (oriented specimens for these two photos collected from a same location, attitude of the foliation 61�\73�). The paired arrowsindicate a sinistral motion.

Fig. 9. Geological map of the Fuyun area, adapted from Briggs et al. (2009). The granite dyke swarm strikes NE and sharply cut the Irtish sinistral strike-slip fault. Mylonitesand migmatites are widely distributed in the gneiss/schist, indicating anatexis of the gneiss/schist during the strike-slip deformation.


Fig. 10. Field photos of the Kekesentao ultramafic–mafic-diorite complex (A).Fuyun granite dyke swarm (B). Kuerti biomodal volcanic rocks composed ofmetamorphic basalt and rhyolite (C).

Fig. 11. Concordia plot of U–Pb data on zircons from biotite gneiss (A), gneissicgranite (B) and blocky granodiorite (C) from the Irtish belt at Ust-Kamenogorsk (seedetailed discussion in the text).

Fig. 12. Concordia plot of U–Pb data on zircons in garnet-bearing biotite gneissfrom northern Buerjin, China.


spot 9.1 yields younger 206Pb/238U and 207Pb/235U ages(300 ± 3 Ma), the reason for which is not clear. The remaining 22analyses are concordant within analytical errors, and yield aweighted mean 206Pb/238U age of 332.1 ± 1.5 Ma (Fig. 13A) (95%confidence level, MSWD = 1.3). This age is regarded as the bestestimation of the crystallization age of the gabbro.

Zircons from the eastern gabbroic pluton (sample 08TW01) aretransparent and colorless and range from 100 to 200 lm in length.They share similar characteristics of the zircons from the coarse-grained gabbro sample from the western pluton both in crystalform and CL images except for their relatively smaller dimensions.Twenty-two analyses were performed on 22 zircon grains of mag-matic origin. These grains show variable abundance of U (47 ppmto 341 ppm) and Th (19 ppm to 179 ppm) with the Th/U ratiosranging from 0.20 to 0.83. Among these, spot 13.1 yields the youn-gest 206Pb/238U and 207Pb/235U ages (285 ± 2 Ma and 293 ± 6 Ma,respectively). The pinkish zircon grain of spot 7.1 yields206Pb/238U age of 1784 Ma, and is likely to be xenocryst. Theremaining 20 analyses are concordant within analytical error,and yield a weighted mean 206Pb/238U age of 336.5 ± 1.3 Ma(Fig. 13B) (95% confidence level, MSWD = 0.48). This age is re-garded as the crystallization age of the eastern gabbro plutonand is consistent with that of the western pluton (sample 09AL25).

Zircons from the granodiorite (sample 08TW02) can be dividedinto two groups. The dominant population is euhedral with lengthranging from 100 lm to 150 lm and length to width ratios of 2–3.

The other group contains stubby grains with 80–120 lm in length.In CL images, the first group of zircons shows oscillatory zoningand the second one exhibits relatively faint oscillatory zoning.

Fig. 13. Concordia plot of U–Pb data on zircons from the Kekesentao ultramafic–mafic-diorite complex (A, western pluton; B, eastern pluton), the biotite granite (C)and potassic granite (D).


Sixteen analyses were conducted on 16 zircon grains and the re-sults show significantly different ages from the two groups. Zirconsfrom group 1 have U ranging from 21 ppm to 123 ppm, Th from121 ppm to 694 ppm and Th/U ratios from 0.14 to 0.41. Six analy-ses have consistent and concordant ages and yield a weightedmean 206Pb/238U age of 315.5 ± 2.1 Ma (MSWD = 0.5) (Fig. 13C).Nine analyses from group two have U ranging from 136 ppm to443 ppm, Th from 27 ppm to 87 ppm and Th/U ratios from 0.06–0.22. All the nine analyses have concordant and consistent206Pb/238U ages within analytical error and yield a weighted meanage of 286.3 ± 1.6 Ma (Fig. 13C). As mentioned previously, thegranodiorite has undergone intense hydrothermal alteration afteremplacement. Considering the morphology of the two groups ofzircons and the low Th/U ratios of the grains from group 2, weinterpret that the granodiorite was emplaced at ca. 315 Ma andthe age of ca. 286 Ma represents post-emplacement hydrothermalalteration event. One spot (8.1) shows a relatively older concordantage on the U–Pb Concordia and is likely to be a xenocryst (Fig. 13C).

Zircons from the granite sample (08TW03) are colorless, trans-parent, euhedral and elongate in shape, ranging in size from150 lm to 200 lm and showing oscillatory zoning in CL images.Fifteen analyses were conducted on 15 zircons. Among these, spot2.1 yields older 206Pb/238U age and is likely to be a xenocryst(381 ± 3 Ma). The other fourteen analyses have U ranging from120 ppm to 530 ppm, Th from 39 ppm to 175 ppm and Th/U ratiosfrom 0.16 to 0.38. The age data are consistent within analyticalerrors, and yield a weighted mean age of 300.3 ± 1.6 Ma(MSWD = 1.2) (Fig. 13D), which is considered to be the bestestimation of the crystallization age of the granite.

5.4. Geochronological data from Mayinebo belt

U–Pb ages on zircons from three Mayinebo samples (04TW3,0410TW3 and 08AL18) were obtained. Zircons from the biotitegneiss (sample 04TW3) show a complex morphology and texturein CL images. The grains range from 50 lm to 150 lm in lengthand most of them are equiaxial. Their bright CL images and anhe-dral forms suggest that most of the grains are likely to be of meta-morphic origin, with only a few zircons exhibiting typicalmagmatic characteristics, such as the oscillatory zoning in CLimages. Among the 21 analyses, spot 1.1 shows high common leadcontents and was therefore rejected. The results of the remaining20 analyses can be broadly divided into three groups accordingto their concordant ages. With respect to their increasing age, thefirst group consists of spots 9.1, 14.1 and 18.1. These three zirconsare round in morphology and have dark CL images with no zoning,and are likely to be metamorphic origin. They have concordant206Pb/238U ages and yield a weighted mean age of 463 ± 15 Ma(n = 3, MSWD = 0.75) (Fig. 14A). Group two contains five spots(2.1, 5.1, 7.1, 11.1, 17.1), among which three spots (5.1, 7.7, 17.1)show bright CL images and the other two (2.1, 11.1) are dark.The zircons with dark CL images have significantly higher U andTh contents compared with the other three zircons with brightCL images. Nevertheless, the five analyses show concordant agesand yield a weighted mean age of 525 ± 13 Ma (n = 5, MSWD = 2.0)(Fig. 14A). Zircons from the third group (spot 4.1, 8.1, 10.1, 12.1,13.1, 15.1, 20.1, 21.1) are elongate and show oscillatory zoning inCL images, with the exception of spot 12.1, which has a bright CLimage and no zoning. This group yields Precambrian 206Pb/238Uages ranging from 817 Ma to 2251 Ma, indicating that they are ofdetrital origin.

Zircons from the migmatite (sample 0410TW3) are mostlyeuhedral and elongate ranging in size from 100 lm to 150 lm. InCL images, they exhibit oscillatory zoning typical of magmaticzircons. Seventeen analyses were conducted on 17 zircons andamong these, only one spot yielded older age (383 Ma), and the

Fig. 14. Concordia plot of U–Pb data on zircons from mylonite in Mayinebo area(eastern segment of the Irtish belt) (A), and migmatite and NE-striking granite dykeswarm to the northwest of Fuyun (B and C) (see text for detailed discussion).


grain is likely to be a xenocryst. Fourteen analyses yield concordantand coherent ages within analytical error and a weighted mean ageof 283 ± 4 Ma, which we correlate to anatexis and formation of themigmatite (Fig. 14B).

Zircons from the granitic dykes (08AL18) in Fuyun area are col-orless, transparent, euhedral and elongate, ranging in size from80 lm to 150 lm, with oscillatory zoning in CL images similar tothat of the zircons crystallized from silicic magmas. Thirteen anal-yses were conducted on 13 zircons which yield variable U, Th con-tents (86–1845 ppm and 21–2518 ppm, respectively) and Th/Uratios (0.25–1.36). Only one spot (7.1) yields older age (ca.400 Ma), which is likely to be xenocryst. The data from other 12analyses are consistent within analytical errors, yielding aweighted mean age of 252.2 ± 2.2 Ma (MSWD = 2.5) (Fig. 14C).

We note that the age obtained in this study is slightly youngercompared with the previously reported age of 277–286 Ma (Gonget al., 2007; Briggs et al., 2009).

6. Geochemistry and petrogenesis

6.1. Geochemistry and petrogenesis of the Kekesentao ultramafic–mafic complex

Whole-rock major and trace element compositions are given inSupplementary Table 2. Based on their major element composi-tions, the rocks could be broadly divided into three sub-groups:ultramafic (MgO > 30%), ultramafic–mafic (MgO = 7.85–27.71%)and intermediate (MgO = 3.21–3.35%), consistent with their petro-graphic characteristics. The large compositional variations of therocks (38.61–66.82% SiO2, 2.57–15.56% Al2O3, 3.21–37.34.% MgO,0.07–12.03% CaO, 0.05–0.67% TiO2, 5.3–11.5% Fe2O3

(t), 0.3–2.4%Na2O, 0.01–2.67% K2O, 0.02–0.11% P2O5, Supplementary Table 2)suggests crystal fractionation/cumulate.

The rocks analyzed in this study show highly variable compat-ible element contents (Supplementary Table 2) suggesting the frac-tionation/cumulate of chromite, olivine, and clinopyroxene. Largevariations in REE contents (

PREE = 1.1–128 ppm) reflect different

abundances and compositions of intercumulus liquids. LREE areuniformly enriched relative to HREE with (La/Yb)N ranging from1.3 to 11 except for two samples 08AL25-3 and 08AL25-7 (mostsamples have (La/Yb)N > 2.0). Positive Eu anomalies (dEu = 1.3–2.3) in the gabbroic samples and the negative Eu anomalies(dEu � 0.75) in the two diorite samples (Fig. 15a) might indicatethe cumulation/fractionation of plagioclase.

Similar to the REE distribution patterns, the primitive mantle-normalized spider diagrams for incompatible elements also exhibitvariable abundances, reflecting the different volume and composi-tions of the intercumulus liquids (Fig. 15). The rocks are anoma-lously depleted in Ti relative to Eu and Tb and depleted in Nbrelative to La with Nb/La ratios ranging from 0.08 to 0.5 (mostwithin 0.3–0.5) (Fig. 15b, chondrite and primitive mantle valuesare from Sun and McDonough, 1989).

As noted before, the ultramafic–mafic-intermediate (diorite)complex has been variably altered after its emplacement, and theincompatible elements, such as Ti, Zr, Nb, Y, Th, U and REE provideuseful indicators to assess this process. The steady increase in theP

REE and HFSE with respect to the SiO2 contents, together withthe petrographic characteristics suggests that the Kekesentaoultramafic–mafic-diorite complex is not a residual mantle perido-tite but is perhaps a cumulate of a basaltic magma. On the otherhand, their calc-alkaline compositions and systematic enrichmentof LREE and LILE and low Nb/La ratios, are consistent with someof the ultramafic–mafic complexes formed in arc settings such asthe Chilas complex in the Kohistan terrane (Takahashi et al.,2007). We therefore link the formation of the Kekesentao complexto cumulation/fractionation of a basaltic magma derived from ametasomatized mantle source.

6.2. Geochemistry and petrogenesis of the granitic dyke swarm in Fuyu

The granite dyke swarm in Fuyun area is highly silicic in com-position with SiO2 showing a range of 71.2–73.5%. Their A/CNK val-ues vary between 0.95–0.98, indicating a weak metaluminousnature. The samples show a sub-alkaline signature according tototal alkali and SiO2 contents. Furthermore, their K2O and Na2Ocontents indicate their high-K calc-alkaline nature (figures notpresented). The

PREE ranges from 85 ppm to 130 ppm. On the

chondrite-normalized patterns, all the samples exhibit enrichmentof LREE (LaN/YbN = 9–11.5) and negative Eu anomalies (dEu = 0.5–

Fig. 15. Chondrite-normalized REE and primitive mantle-normalized incompatible elements pattern of the Kekesentao ultramafic–mafic-diorite complex and the Fuyungranite dyke swarm. Both the chondrite and the primitive mantle values are from Sun and McDonough (1989).

Fig. 16. Age data histogram of pre-Paleozoic zircon data from the metasedimentaryrocks in the Altai-Mongolia terrane. The data from gneisses along the Irtish beltfrom this study are also included. Only ages >370 Ma were used (N = 308). Data are


0.8) (Fig. 15c). On the primitive-mantle normalized spider diagram,the rocks show a significant trough for Nb, Sr, P and Ti (Fig. 15d).

It is obvious that the Fuyun granite dyke swarm was derivedfrom the partial melting of crustal materials due to their highSiO2, Al2O3 and low Zr, Nb, Y contents (Supplementary Table 2).Their negative Eu anomalies could be ascribed to a plagioclaseresiduum in the source. Hornblende and mica are the most com-mon hydrous minerals involved in dehydration-melting that gen-erate granitic magmas. Partial melts derived from mica-richpelite and greywacke and from a hornblende-rich source can bedetermined by their molar ratios of Al2O3/(MgO + FeOT) and CaO/(MgO + FeOT) (Rapp, 1995; Rapp and Watson, 1995). In line withtheir Al2O3/(MgO + FeOT) (3.7–4.4) and CaO/(MgO + FeOT) (0.8–1.0) ratios, the granite dyke swarm is inferred to be derived frompartial melting of metagreywacke. Furthermore, their relativelylow Sr and Sr/Y ratios (less than 20), together with the weakly frac-tionated HREE (DyN/YbN � 1.0), suggest melting in the garnetstability field (Patiño Douce, 1996).

from Zhou et al. (2006), Yuan et al. (2007a,b), this study and unpublished data(Zhou Gang, unpublished) (N = 42). The inset shows the U–Pb age data histogram ofpre-Late Paleozoic zircons from granites in the Altai-Mongolia terrane (data arefrom Wang et al. (2008), Zhou et al. (2006) and unpublished data of Zhou Zhang).

7. Discussion

7.1. Metamorphic event and igneous activity in the Altai-Mongolianterrain

In the age histogram combining all zircon analyses from the Pre-Devonian metamorphic rocks in the Altai-Mongolian terrain (datafrom Yuan et al., 2007a, 2007b; Zhou et al., 2007 and this study;Fig. 16), the zircons with ages >370 Ma are mainly detrital and/orinherited from metamorphosed volcano-sedimentary rocks, includ-ing some grains of metamorphic origin. In general, the zircons fromthe metamorphic rocks exhibit a wide age spectrum ranging from3032 Ma to ca. 370 Ma, but mainly cluster in four peaks at ca.394 Ma, ca. 514 Ma, ca. 810 Ma and ca. 1790 Ma. On the other hand,the episodes of granitoid magmatism in this area show peaks at370 Ma, 405 Ma, 462 Ma and 513 Ma (data from Wang et al.(2006), Zhou et al. (2006, 2007), Yuan et al. (2007a), inset inFig. 16). Among these four episodes, the ca. 405 Ma granites occupyabout 80% of the total outcrop area of the granitic rocks. Previousstudies on the granites in Altai-Mongolian terrain show that the

ca. 530–400 Ma granites possess typical arc-signatures (Wanget al., 2005, 2006, 2009; Zhou et al., 2007, 2009a), which is consis-tent with the conclusion of a Cambrian–Ordovician arc in the Altairegion as suggested by Briggs et al. (2007). On the other hand,in situ zircon U–Pb dating of the high-grade metamorphic rocksin Altai-Mongolian terrain indicates the wide occurrence of meta-morphic zircons with ages of ca. 460 Ma and ca. 390 Ma. Thus,although it is reasonable to correlate the formation of theAltai-Mongolian terrain with the above ages, the subduction polar-ity remains equivocal (Sun et al., 2008; Xiao et al., 2009b; Briggset al., 2007, 2009). Our study reveals metamorphic ages of ca.525 Ma and ca. 463 Ma from the gneisses in Mayinebo area andca. 400–380 Ma metamorphism along the northern margin of theIrtish belt. Thus, multiple episodes of subduction below the Altaiarc could explain the multiple episodes of magmatic pulses witharc-signature along with metamorphic events in the Altaiorogenic belt.


7.2. The Junggar terrain: a juvenile terrane formed by multiplecollision of intra-ocean arc, seamounts and ophiolite complex

Recent studies in eastern Junggar (Windley et al., 2002; Jianet al., 2005; Wu et al., 2006; Tang et al., 2007; Tong et al., 2006;Xiao et al., 2009a, 2009b, 2011; Yuan et al., 2010; Long et al.,2012; Yang et al., 2012), have revealed the occurrence of severalophiolitic mélanges of different ages (from 503 Ma to 336 Ma).An intra-ocean subduction and seamounts accretion in the Junggarterrane together with an ‘‘arc-signature’’ proto-crust has been in-ferred (Xiao et al., 2009a,b). This process might have initiated inthe Cambrian and lasted till 330 Ma, as suggested by the presenceof the ultramafic–mafic complex with arc signature in Kekesentaoand the youngest ophiolite in Junggar dated at ca. 350 Ma (Wuet al., 2006). On the other hand, the ca. 320–260 Ma granites andmafic intrusions in Junggar exhibit geochemical signatures consis-tent with a post-collision tectonic process (Fig. 18, Han et al.,1997).

Fig. 18. Nb + Y versus Rb diagram of the Fuyun granite dyke swarm. The 320–250 Ma granites are also included (data are from Han et al. (1997), Wang et al.(2006, 2007, 2009), Tong et al. (2006), Zhou et al. (2006), Yuan et al. (2007, 2010),Zhang et al. (2010a). See detailed discussion in the text).

7.3. Evolution of the Irtish belt

The remarkable contrast in the sedimentary facies and igneousrocks between the Altai-Mongolian terrain and the Junggar ter-rain argue that the Irtish belt marks the terminal suture betweenthe two tectonic units (Xinjiang BGMR, 1993). This leads to anumber of questions regarding the timing of suturing and thenature of tectonic evolution from suture to post-collisional orog-eny. Here we propose a tectonic model based on the data pre-sented in this study and previous works, which envisages thefollowing stages. (1) As the oceanic crust subducted with a north-ward polarity along the Irtish zone during Devonian to Early Car-boniferous, a back-arc basin represented by the Kuerti bimodalvolcanic rocks was formed at the southern margin of the Altai-Mongolia terrain (Xu et al., 2003; Zhang et al., 2008a). The ca.372 Ma Kuerti bimodal volcanic rocks might represent one mem-ber of an active arc-back-arc basin system (Fig. 19a and b) (Xuet al., 2001; Niu et al., 1999). (2) The final closure between theAltai-Mongolian terrain and the Junggar terrain took place atca. 320 Ma or slightly earlier as indicated by the continentalfacies of the upper Carboniferous to Permian strata and thepost-orogenic and/or intraplate geochemical signatures of theintrusive rocks emplaced after 320 Ma (Fig. 19b and c) (XinjiangBGMR, 1993; Han, 2000; Zhou et al., 2007, 2009a; Wang et al.,2005; Tong et al., 2006). The geochemical signature of the Keke-sentao ultramafic–mafic complex is consistent with an arc-signa-ture, and the complex was most likely formed at the root of an

Fig. 17. Late Carboniferous to Permian mafic intrusions and granites in Altaid, the Irtishadditional information from Tong et al. (2007), Zhou et al. (2009a,b), Zhang et al. (2010

arc to the south of the Irtish belt, during the closure of the oce-anic basin between the Altai-Mongolian terrain and the Junggarterrain. The tectonic framework in this case is similar to that ofthe Chilas ultramafic–mafic complex in the Kohistan terrain(Takahashi et al., 2007). As the Junggar and Altai-Mongolian ter-rains were amalgamated, the detachment of the subducted slabled to partial melting of the juvenile mafic crust resulting involuminous ca. 320–290 Ma post-orogenic type granites both atthe southern Altai-Mongolian terrain and in the northern of theJunggar terrain (Figs. 17–19c) (see detailed discussions on theirpetrogenesis by Yuan et al., 2007b; Wang et al., 2006; Zhouet al., 2007, 2009). (3) During the clockwise rotation of the Sibe-ria craton (Buslov et al., 2004) and the northward movement ofthe Junggar terrain at ca. 290–275 Ma, the sinistral strike-slipmotion along the Irtish belt resulted in ductile shearing alongthis belt, leading to the partial melting of the crustal material.This resulted in the formation of migmatites and the syn-tectonicgneissic granites, such as the ca. 283 Ma gneissic granites andmigmatites exposed in the Mayinebo area and the ca. 281 Magneissic granite in Ust-Kamenogorsk. During this period, the Tar-im mantle plume (Zhang et al., 2008b, 2010a,b; Zhou et al.,2009b; Tian et al., 2010), might have partially contributed tothe formation of the diverse igneous rocks along the Irtish beltbecause only ductile shearing effect rarely leads to partial

belt and Junggar Block (modified after the original figure of Wang et al. (2006) witha,b)).

Fig. 19. Schematic model of the Paleozoic tectonic evolution of the Altai-Mongolia terrain, Irtish belt and Junggar terrain, as proposed in the present study. (a) Before 350 Ma,a single long-lived arc (the Altai-Mongolia terrain, abbreviated as AM in the figure) and collision of multiple arcs, seamount and micro-continents (the Junggar) were involvedin the formation of the juvenile terrains. (b) At ca. 350–320 Ma, following the consumption of the oceanic crust between Altai-Mongolian terrain and Junggar terrain, theIrtish suture zone between Altai-Mongolia terrane and the Junggar Block formed. (c and d) At ca. 320–290 Ma, slab-detachment resulted in the formation of post-orogenicgranites. Simultaneously, the sinistral strike-slip ductile deformation took place during 290–280 Ma and culminated at ca. 275 Ma. The 290–250 Ma magmatic pulses weregenetically linked to the Permian Tarim mantle plume.


melting of crustal material. The plume activity supplied enoughheat, coupled with the shearing effect, to induce the formationof the migmatites and gneissic granites. (4) The sinistral strike-slip deformation of the Irtish belt culminated at ca. 275 Ma withthe emplacement of the voluminous A-type granites and anoro-genic mafic intrusions along the Irtish belt and within the Jung-gar terrain during 275–250 Ma. Though the Fuyun granite dykeswarm exhibits geochemical features consistent with an arc-sig-nature (Fig. 18), these dykes might not have formed in an arc set-ting because the consistent strike direction of these rocks isperpendicular to the strike of the Irtish suture zone. The coevalbimodal intrusive complex (alkaline gabbro and A-type granite,Zhang et al., 2010a) and A-type granites in Altay and Qinghe area(Han et al., 1997; Wang et al., 2006; Tong et al., 2007), the Fuyungranite dyke swarm, as well as the coeval granodiorite in Ust-Kamenogorsk, all formed in an anorogenic extensional setting,probably reflecting the magmatic pulses associated with thePermian Tarim mantle plume. Furthermore, the high-temperatureand low-pressure mafic granulite formed at ca. 270 Ma along theIrtish belt could also be ascribed to metamorphism geneticallyrelated to the Permian mantle plume rather than plate subduc-tion and collision (Chen et al., 2006). The above model arguesagainst the notion that the subduction in this region lasted tillTriassic as well as the model of Permian north-dipping subduc-tion of the Junggar Ocean (Xiao et al., 2009b).

8. Conclusions

We draw the following general conclusions based on the datapresented in this study, in conjunction with those from previousstudies.

(1) The Irtish suture zone between Altai-Mongolian terrain andthe Junggar terrain formed at ca. 320 Ma. The sinistral strike-slip ductile deformation took place during 290–275 Ma andculminated at ca. 275 Ma. Ductile shearing, coupled withplume-related heating, induced the formation of the 290–275 Ma migmatites and gneissic granites. The 275–250 Mamagmatic pulses were genetically linked to the PermianTarim mantle plume.

(2) Both the syn-subduction strike-slip duplication of a singlelong-lived arc (e.g., the Altai-Mongolia terrain) and collisionof multiple arcs and micro-continents (e.g., the Junggar ter-rain) were involved in the tectonic evolution and Paleozoiccontinental growth of the Altai orogen.

(3) The data obtained in this study, as well as the regional geo-logical features and recent geochronological informationfrom the eclogite in Tienshan (Gao et al., 2009), do not favormodels that assume that subduction lasted until Triassic inAltai, Junggar and Tienshan areas (Zhang et al., 2007; Xiaoet al., 2009a,b). The CAOB in western China was formed nolater than end Carboniferous.

Acknowledgements

We thank Prof. Hui-Kun Li and Hui-Min Li for their assistancewith LA-ICPMS zircon U–Pb analyses. We sincerely thank Prof.Bor-Ming Jahn and an anonymous reviewer for their detailed, crit-ical and constructive reviews that significantly improved the qual-ity of this paper. This study is financially supported by the MajorState Basic Research Program of the PR China (2011CB808903), Na-tional Basic Research Program of China (2011BAB06B03) and the


CAS/SAFEA International Partnership Program for Creative Re-search Teams (KZCX2-YW-t004).

Appendix A. Supplementary material

Supplementary data associated with this article can be found,in the online version, at http://dx.doi.org/10.1016/j.jseaes.2012.02.016.

References

Ao, S.J., Xiao, W.J., Han, C.M., Mao, Q.G., Zhang, J.E., 2010. Geochronology andgeochemistry of Early Permian mafic–ultramafic complexes in the Beishan area,Xinjiang, NW China: implications for the late Paleozoic tectonic evolution of thesouthern Altaids. Gondwana Research 18, 466–478.

Badarch, G., Cunningham, D., Windley, B.F., 2002. A new terrane subdivision forMongolia: implications for the Phanerozoic crustal growth of Central Asia.Journal of Asian Earth Sciences 21, 87–110.

Bai, W.J., Zhou, M.F., 1989. Study on the chemical compositions of the pyroxene inthe Hongguleneng ophiolite, Xinjiang. Geology Review 35, 107–118 (in Chinesewith English abstract).

Bai, W.J., Zhou, M.F., 1991. Geochemical characteristics and origin of the cumulatesof the Hongguleneng ophiolite, Xinjiang. Bulletin of the Chinese Academy ofGeological Sciences 24, 63–78 (in Chinese with English abstract).

Borisenko, A.S., Sotnikov, V.I., Izokh, A.E., Polyakov, G.V., Obolensky, A.A., 2006.Permo-Triassic mineralization in Asia and its relation to plume magmatism.Russian Geology and Geophysics 47, 166–182.

Briggs, M.S., Maning, C.E., Chen, Z.L., Wang, X.F., Grove, M., 2007. Late Paleozoictectonic history of the Ertis fault in the Chinese Altai and its implications for thedevelopments of the Central Asian Orogenic System. Geological Society ofAmerican Bulletin 119, 944–960.

Briggs, M.S., Yin, A., Manning, C.E., Chen, Z.L., Wang, X.F., 2009. Tectonicdevelopment of the southern Chinese Altai range as determined by structuralgeology, thermobarometry, 40Ar/39Ar thermochronology, and Th/Pb ion-microprobe monazite geochronology. Geological Society of American Bulletin121, 1381–1393.

Buslov, M.M., Saphonova, I.Y., Watanabe, T., Obut, O.T., Fujiwara, Y., Iwata, K.,Semakov, N.N., Sugai, Y., Smirnova, L.V., Kazansky, A.Y., 2001. Evolution of thePlaeo-Asian Ocean (Altai-Sayan region, Central Asia) and collision of possibleGondwana-derived terranes with the southern marginal part of the Siberiancontinent. Geosciences Journal 5, 203–224.

Buslov, M.M., Watanbe, T., Smirnova, L.V., Fujiwara, I., Iwata, K., de Grave, J.,Semakov, N.N., Travin, A.V., Kir’yanova, A.P., Kokh, D.A., 2003. Role of strike-slipfaulting in Late Plaeozoic–Early Mesozoic tectonics and geodynamics of theAltai-Sayan and East Kazakhstan regions. Russian Geology and Geodynamics 44,49–75.

Buslov, M.M., Watanbe, T., Fujiwara, I., Iwata, K., Smirnova, L.V., Safonova, I.Y.,Semakov, N.N., Kiryanova, A.P., 2004. Late Paleozoic faults of the Altai region,Central Asia: tectonic pattern and model of formation. Journal of Asian EarthSciences 23, 655–671.

Carroll, A.R., Liang, Y., Graham, S.A., Xiao, X.C., Hendrix, M.S., Chu, J., McKnight, C.L.,1990. Junggar Basin, northwestern China: trapped late Paleozoic ocean.Tectonophysics 181, 1–4.

Carroll, A.R., Graham, S.A., Hendrix, M.S., Ying, D., Zhou, D., 1995. Late Paleozoictectonic amalgamation of northwestern China: sedimentary record of thenorthern Tarim, northwestern Turpan, and southern Junggar basins. GeologySociety of America Bulletin 107, 571–594.

Chen, B., Jahn, B.M., 2004. Genesis of post-collisional granitoids and basementnature of the Junggar Terrane, NW China: Nd–Sr isotope and trace elementevidence. Journal of Asian Earth Sciences 23, 691–703.

Chen, H.L., Yang, S.F., Li, Z.L., Yu, X., Xiao, W.J., Yuan, C., Lin, X.B., Li, J.L., 2006. ZirconSHRIMP U–Pb chronology of the Fuyun basic granulite and its tectonicsignificance in Altaid orogenic belt. Acta Petrologica Sinica 22, 1351–1358 (inChinese with English abstract).

Cunningham, D., 2005. Active intracontiental transpressional mountain building inthe Mongolia Altai: defining a new class of orogen. Earth and Planetary ScienceLetters 240, 436–444.

Cunningham, W.D., Windley, B.F., Dorjnamjaa, D., Badamgarov, G., Saandar, M.,1996. A structural transect across the Mongolian Western Altai: activetranspressional mountain building in central Asia. Tectonics 15, 142–156.

Dobretsov, N.L., 2003. Evolution of structures of the Urals, Kazakhstan, Tienshan andAltai-Sayan region within the Ural-Mongolian fold belt (Paleoasian Ocean).Russian Geology and Geophysics 44, 5–27.

Dobretsov, N.L., Buslov, M.M., Vernikoveky, V.A., 2003. Neoproterozoic to earlyOrdovician evolution of the Paleo-Asia Ocean: implications to the break-up ofRodinia. Gondwana Research 6, 143–159.

Dobretsov, N.L., Buslov, M.M., Sofonova, I.Y., Kokh, D.A., 2004. Fragments of oceanicislands in the Kurai and Katun accreationary wedges of Gorny Altai. RussianGeology and Geophysics 45, 1381–1403.

Dong, Y.G., Zhang, C.L., Rui, X.J., Zhao, Y., Guo, K.Y., 2002. Copper–GoldMineralization along Habahe River and Buerjin River. Geological PublishingHouse, Beijing, pp. 1–135 (in Chinese).

Gao, J., Long, L.L., Klemd, R., Qian, Q., Liu, D.Y., Xiong, X.M., Su, W., Liu, W., Wang,Y.T., Yang, F.Q., 2009. Tectonic evolution of the South Tianshan Orogen, NWChina: geochemical and age constraints of granitoid rocks. International Journalof Earth Sciences 98, 1221–1238.

Glorie, S., De Grave, J., Buslov, M.M., Zhimulev, F.I., Izmer, A., Vandoome, W.,Ryabinin, A., Van den haute, P., Vanhaecke, F., Elburg, M.A., 2011. Formation andPalaeozoic evolution of the Gorny-Altai-Mongolia suture zone (South Siberia):zircon U/Pb constraints on the igneous record. Gondwana Research 20, 465–484.

Gong, H.L., Chen, Z.L., Hu, Y.Q., Li, L., Lai, X.R., Ma, Q.Y., Li, Y.Y., Hu, B., Zhang, W.G.,2007. Geochemical characteristics of the acid dyke swarm from the easternsegment of the Ertix (Irtish) tectonic belt, Altai orogeny and its geologicalimplications. Acta Petrologica Sinica 23, 889–899 (in Chinese and with Englishabstract).

Han, Y.L., 2000. Paleogeography of the Permian in Xinjiang. Xinjiang Geology 18,330–334 (in Chinese with English abstract).

Han, B.F., Wang, S.G., Jahn, B.M., Hong, D.W., Kagami, H., Sun, Y.L., 1997. Depleted-mantle source for the Ulungur River A-type granites from North Xinjiang,China: geochemistry and Nd–Sr isotopic evidence, and implications forPhanerozoic crustal growth. Chemical Geology 138, 135–159.

Han, B.F., Ji, J.Q., Song, B., Chen, L.H., Zhang, L., 2006. Late Paleozoic vertical growthof continental crust around the Junggar Basin, Xinjiang, China (Part I): timing ofpost-collisional plutonism. Acta Petrologica Sinica 22, 1077–1086 (in Chinesewith English abstract).

He, G.Q., Han, B.F., Yue, Y.J., Wang, J.H., 1990. Tectonic division and crustal evolutionof Altay Orogenic Belt in China. Geoscience (Xinjiang) 2, 9–20 (in Chinese withEnglish Abstract).

He, G.Q., Li, M.S., Liu, D.Q., Zhou, N.H., 1994. Paleozoic Crustal Evolution andMineralization in Xinjiang of China. Xinjiang Peoples Publishing House,Urumuqi, pp. 1–256 (in Chinese with English abstract).

He, G.Q., Li, J.Y., Hao, J., Li, J.L., Cheng, S.D., Xu, X., Xiao, X.C., Tian, P.R., Deng, Z.Q.,Li, Y.A., Guo, F.X., 2001. Crustal structure and evolution of Xinjiang, China.Chinese National 305 Project 07-01. Urumuqi, Xinjiang, China, pp. 26–78 (inChinese).

Hu, A.Q., Wei, G.J., 2003. A review of the ages of the basement rocks from JungggarBasin in Xinjiang, China. Xinjiang Geology 21, 398–406 (in Chinese with Englishabstract).

Hu, A.Q., Zhang, G.X., Zhang, Q.F., Li, T.D., Zhang, J.B., 2002. A review on ages ofPrecambrian metamorphic rocks in Altai orogen in Xinjiang, NW China. ChineseJournal of Geology 37, 129–142 (in Chinese with English abstract).

Hu, A.Q., Wei, G., Deng, W.M., Chen, L., 2006. SHRIMP zircon U–Pb dating and itssignificance for gneisses from southeastern area to Qinghe County in the Altai,China. Acta Petrologica Sinica 22, 1–10 (in Chinese with English abstract).

Jahn, B.M., Wu, F.Y., Chen, B., 2000. Granitoids of the Central Asian Orogenic Belt andcontinental growth in the Phanerozoic. Transactions of the Royal Society ofEdinburgh, Earth Sciences 91, 1810193.

Jahn, B.M., Windley, B., Batal’in, B., Dobretsov, N., 2004. Phanerozoic continentalgrowth in Central Asia. Journal of Asian Earth Sciences 23, 599–603.

Jahn, B.M., Litvinovsky, B.A., Zanvilevich, A.N., Reichow, M., 2009. Peralkalinegranitoid magmatism in the Mongolian–Transbaikalian Belt: evolution,petrogenesis and tectonic significance. Lithos 113, 521–539.

Jian, P., Liu, D.Y., Shi, Y.R., Sun, F.Q., 2005. SHRIMP dating of SSZ ophiolites fromnorthern Xinjiang Province, China: implications for generation of oceanic crustin the Central Asian Orogenic Belt. In: Sklyarov, E.V. (Ed.), Structural andTectonic Correlation across the Central Asian Orogenic Collage: North-easternSegment, Guide Book and Abstract Volume of the Siberian Workshop IGCP480,IEC SB RASm Irkutsh, p. 246.

Lei, R.-X., Wu, C.-Z., Gu, L.-X., Zhang, Z.-Z., Chi, G.-X., Jiang, Y.-H., 2011. Zircon U–Pbchronology and Hf isotope of the Xingxingxia granodiorite from the CentralTianshan zone (NW China): implications for the tectonic evolution of thesouthern Altaids. Gondwana Research. http://dx.doi.org/10.1016/j.gr.2011.02.010.

Li, J.Y., 2006. Permian geodynamic setting of Northeast China and adjacent regions:closure of the Paleo-Asian Ocean and subduction of the Paleo-Pacific Plate.Journal of Asian Earth Sciences 26, 207–224.

Li, T.D., Poliyangsiji, B.H., 2001. Tectonic and crustal evolution of Altai in China andKazakhstan. Xinjiang Geology 19, 27–32 (in Chinese with English abstract).

Li, X.H., Li, Z.X., Wingate, M.T.D., Chung, S.L., Liu, Y., Lin, G.C., Li, W.X., 2006.Geochemistry of the 755 Ma Mundine Well dyke swarm, northwesternAustralia: part of a Neoproterozoic mantle superplume beneath Rodinia?Precambrian Research 146, 1–15.

Long, X.P., Sun, M., Yuan, C., Xiao, W.J., Cai, K.D., 2008. Early Paleozoic sedimentaryrecord of the Chinese Altai: implications for its tectonic evolution. SedimentaryGeology 208, 88–100.

Long, X., Yuan, C., Sun, M., Safonova, I., Xiao, W., Wang, Y., 2012. Geochemistry andU–Pb detrital zircon dating of Paleozoic graywackes in East Junggar, NW China:insights into subduction–accretion process in the southern Central AsianOrogenic Belt. Gondwana Research 21, 637–653.

Ludwig, K.R., 1999. Using Isoplot/EX, Version 2, A Geolocronolgical Toolkit forMicrosoft Excel. Berkeley Geochronological Center Special, Publication 1a, p. 47.

Ludwig, K.R., 2001. Squid 1.02: A User Manual. Berkeley Geochronological CenterSpecial, Publication l2, p. 19.

Melnikov, A., Delvaux, D., Travin, A., Buslov, M., Vladimirov, A., Smirnova, L.,Theunissen, K., 1997. Late Paleozoic–Early Mesozoic sinistral movement alongthe Irtysh shear zone, NE Kazakhstan. Tectonic Studies Group Annual GeneralMeeting, Durham, 17–19 December.



http://dx.doi.org/10.1016/j.gr.2011.02.010



Melnikov, A., Travin, A., Plotnikov, A., Smirnova, L., Theunissen, K., 1998. Kinematicsand Ar/Ar geochronology of the Irtysh shear zone in NE Kazakhstan. In:Continental Growth in the Phanerozoic: Evidence from East-Central Asia. FirstWorkshop, IGCP-420, Urumqi, China, 27 July–3rd August, p. 30.

Mossakovsky, A.A., Ruzhentsev, S.V., Samygin, S.G., Kheraskova, T.N., 1993. TheCentral Asian fold belt: geodynamic evolution and formation history.Geotectonics 26, 455–473.

Niu, H.C., Xu, J.F., Yu, X., Chen, F., Zheng, Z., 1999. Discovery of the Mg-rich volcanicsin Altay, Xinjiang, and its geological implications. Chinese Science Bulletin 44,1685–1688.

Niu, H.C., Sato, H., Zhang, H.X., Tto, J., Yu, X.Y., Nagao, T., Terada, K., Zhang, Q., 2006.Juxtaposition of adakite, boninite, high-TiO2 and low-TiO2 basalts in theDevonian southern Altay, Xinjiang, NW China. Journal of Asian Earth Sciences28, 439–456.

Patiño Douce, A.E., 1996. Effects of pressure and H2O content on the compositions ofprimary crustal melts. Transactions of the Royal Society of Edinburgh, EarthSciences 87, 11–21.

Pirajno, F., Ernst, R.E., Borisenko, A.S., Fedoseev, G., Naumov, E.A., 2009. Intraplatemagmatism in central Asia and China and associated metallogeny. Ore GeologyReviews 35, 114–136.

Rapp, R.B., 1995. Amphibole-out phase boundary in partially melted metabasalt, itscontrol over liquid fraction and composition, and source permeability. Journalof Geophysical Research 100 (15), 601–615.

Rapp, R.P., Watson, E.B., 1995. Dehydration of metabasalt at 8–32 kbar: implicationsfor continental growth and crust–mantle recycling. Journal of Petrology 36,891–931.

Rojas-Agramonte, Y., Kröner, A., Demoux, A., Xia, X., Wang, W., Donskaya, T., Liu, D.,Sun, M., 2011. Detrital and xenocrystic zircon ages from Neoproterozoic toPalaeozoic arc terranes of Mongolia: significance for the origin of crustalfragments in the Central Asian Orogenic Belt. Gondwana Research 19, 751–763.

Rorarash, A.I., Samygin, S.G., Gredyushko, Y.A., Keyl’man, G.A., Mileyev, V.S.,Perfil’yev, A.S., 1982. The Devonian active continental margin in thesouthwestern Altai. Geotectonics 16, 1683–1699.

Ruzhentsev, S.V., Mossakovskiy, A.A., 1996. Geodynamics and tectonic evolution ofthe Central Asian Paleozoic structures as the result of the interaction betweenthe Pacific and Indo-Atlantic segments of the Earth. Geotectonics 29, 294–311.

Sengör, A.M.C., Natal’in, B.A., Burtman, V.S., 1993. Evolution of the Altaid tectoniccollage and Paleozoic crustal growth in Eurasia. Nature 364, 299–307.

Sun, S.S., McDonough, W.F., 1989. Chemical and isotopic systematics of oceanicbasalt: implication for mantle composition and processes. In: Saunders, A.D.,Norry, M.J. (Ed.), Magmatism in the Ocean Basin. Geol. Soc. London Spec. Publ.42, pp. 528–548.

Sun, M., Yuan, C., Xiao, W., Long, X., Xia, X., Zhao, G., Lin, S., Wu, F., Kröner, A., 2008.Zircon U–Pb and Hf isotopic study of gneissic rocks from the Chinese Altai:progressive accretionary history in the early to middle Paleozoic. ChemicalGeology 247, 352–383.

Takahashi, Y., Mikoshiba, M.U., Takahashi, Y., Kausar, A.B., Khan, T., Kubo, K., 2007.Geochemical modeling of the Chilas complex in the Kohistan terrane, northernPakistan. Journal of Asian Earth Sciences 29, 336–349.

Tang, H.F., Su, Y.P., Liu, C.Q., Hou, G.S., Zhang, Y.B., 2007. Zircon U–Pb age of theplagiogranite in Kelamaili belt, northern Xinjiang and its tectonic implications.Geotectonic et Metallogenia 31, 110–117 (in Chinese with English abstract).

Tian, W., Campbell, T.H., Allen, C., Guan, P., Pan, W.Q., Chen, M.M., Yu, H.J., Zhu, W.P.,2010. The Tarim picrite–basalt–rhyolite suite, a Permian flood basalt fromnorthwest China with contrasting rhyolites produced by fractionalcrystallization and anatexis. http://dx.doi.org/10.1007/s00410-009-0485-3.

Tong, Y., Wang, T., Kovach, V.P., Hong, D.W., Han, B.F., 2006. Age and origin of theTakeshiken postorogenic alkali-rich intrusive rocks in southern Altai, nearMongolian border in China and its implications for continental growth. ActaPetrologica Sinica 22, 1267–1278 (in Chinese with English abstract).

Tong, Y., Wang, T., Hong, D.W., Dai, Y.J., Han, B.F., Liu, X.M., 2007. Ages and origin ofthe early Devonian granites from the north part of Chinese Altai mountains andits tectonic implications. Acta Petrologica Sinica 23, 1933–1944 (in Chinesewith English abstract).

Travin, A.V., Vladimirov, V.G., Boven, A., 2001. Implication of 40Ar/39Ar data on thetectonothermal evolution of the Irtysh shear zone (Eastern Kazakhstan). In:Jahn, B.M. (Ed.), Continental Growth in the Phanerozoic: Evidence from CentralAsia: IGCP 480 Conference Abstract Volume, pp. 106–107.

Vladimirov, A.G., Ponomareva, A.P., Shokalskii, S.P., Khalilov, V.A., Kostitsyn, Y.A.,Ponomarchuk, V.A., Rudnev, S.N., Vystavnoi, S.A., Kruk, N.N., Titov, A.V., 1997.Late Paleozoic–Early Mesozoic granitoid magmatism in Altai. Russian Geologyand Geophysics 38, 755–770.

Wang, T., Hong, D.W., Tong, Y., Han, B.F., Shi, Y.R., 2005. Zircon U–Pb SHRIMP ageand origin of post-orogenic Lamazhao granitic pluton from Altai orogen: itsimplications for vertical continental growth. Acta Petrologica Sinica 21, 640–650 (in Chinese with English abstract).

Wang, T., Hong, D.W., Jahn, B.M., Tong, Y., Wang, Y.B., Han, B.F., Wang, X.X., 2006.Zircon U–Pb geochronology and geochemistry of Paleozoic syn-orogenicintrusions from the Chinese Altai: implications for subduction-accretionprocesses. Journal of Geology 114, 735–751.

Wang, T., Tong, Y., Jahn, B.M., Zou, T.R., Wang, Y.B., Hong, D.W., Han, B.F., 2007.SHRIMP U–Pb zircon geochronology of the Altai No. 3 Pegmatite, NW China, andits implications for the origin and tectonic setting of the pegmatite. Ore GeologyReviews 32, 325–336.

Wang, T., Li, W.P., Li, J.B., Hong, D.W., Tong, Y., 2008. Increase of juvenal mantle-derived composition from syn- orogenic to post-orogenic granites of the east

part of the east Tian Shan (China) and implications for continental verticalgrowth: Sr and Nd isotopic evidence. Acta Petrologica Sinica 24, 763–772 (inChinese with English abstract).

Wang, T., Jahn, B.M., Kovach, V.P., Tong, Y., Hong, D.W., Han, B.F., 2009. Nd–Srisotopic mapping of the Chinese Altai and implication for continental growth inthe Central Asian Orogenic Belt. Lithos 110, 359–372.

Williams, I.S., 1998. U–Th–Pb geochronology by ion microprobe. Reviews onEconomical Geology 7, 1–35.

Windley, B.F., Kroner, A., Guo, J., Qu, G., Li, Y., Zhang, Z.C., 2002. Neoproterozoic toPaleozoic geology of the Altai orogen, NW China: new zircon age data andtectonic evolution. Journal of Geology 110, 719–739.

Windley, B.F., Alexeiev, D., Xiao, W.J., Kröner, A., Badarch, G., 2007. Tectonic modelsfor accretion of the Central Asian Orogenic Belt. Journal of Geological Society164, 31–47.

Wu, B., He, G.Q., Wu, T.R., Li, H.J., Luo, H.L., 2006. Discovery of the Buergen ophioliticmélanges belt in Xinjiang and its tectonic significance. Geology in China 33,476–486 (in Chinese with English abstract).

Xiao, W.J., Windley, B.F., Badarch, G., Sun, S., Li, J.L., Qin, K.Z., Wang, Z.H., 2004.Palaeozoic accretionary and convergent tectonics of the southern Altaids:implications for the lateral growth of Central Asia. Journal of Geological Society,London 161, 339–342.

Xiao, W.J., Han, C.M., Sun, M., Lin, S.F., Chen, H.L., Li, Z.L., Li, J.L., Sun, S., 2008a.Middle Cambrian to Permian subduction-related accretionary orogenesis ofNorth Xinjiang, NW China: implications for the tectonic evolution of CentralAsia. Journal of Asian Earth Sciences 32, 102–117.

Xiao, W.J., Windley, B.F., Yuan, C., Sun, M., Han, C.M., Lin, S.F., Chen, H.L., Yan, Q.R.,Liu, D.Y., Qin, K.Z., Li, J.L., Sun, S., 2008b. Paleozoic multiple subduction-accretion processes of the southern Altaids. American Journal of Science 309,221–270.

Xiao, W.J., Windley, B.F., Huang, B.C., Han, C.M., Yuan, C., Chen, H.L., Sun, M., Sun, S.,Li, J.L., 2009a. End-Permian to middle Triassic termination of the accretionaryprocesses of the southern Altaids: implications for the geodynamic evolution,Phanerozoic continental growth, and metallogeny of Central Asia. InternationalJournal of Earth Sciences. http://dx.doi.org/10.1007/s00531-008-0407.

Xiao, W.J., Windley, B.F., Yuan, C., Sun, M., Han, C.M., Lin, S.F., Chen, H.L., Yan, Q.R.,Liu, D.Y., Qin, K.Z., Sun, S., 2009b. Paleozoic multiple subduction-accretionprocesses of the southern Altaids. American Journal of Sciences 309, 221–270.

Xiao, Y., Zhang, H., Shi, J., Su, B., Sakyi, P.A., Lu, X., Hu, Y., Zhang, Z., 2011. LatePaleozoic magmatic record of East Junggar, NW China and its significance:implications from zircon U–Pb dating and Hf isotope. Gondwana Research 20,532–542. http://dx.doi.org/10.1016/j.gr.2010.12.008.

Xinjiang, BGMR, 1993. Regional Geology of the Xinjiang Uygur Autonomous Region.Geological Publishing House, Beijing, pp. 17–45 (in Chinese).

Xu, J.F., Mei, H.L., Xu, Y.G., 2001. Adakites related to subduction in the northernmargin of Junggar arc for the Late Paleozoic: products of slab melting. ChineseScience Bulletin 46, 1312–1316.

Xu, J.F., Castillo, P.R., Chen, F.R., Niu, H.C., Xu, Y.G., Zhen, Z.P., 2003. Geochemistry oflate Paleozoic mafic igneous rocks from the Kuerti area, Xinjiang, northwesternChina: implications for backarc mantle evolution. Chemical Geology 193, 137–154.

Yang, X.-F., He, D.-F., Wang, Q.-C., Tang, Y., Tao, H.-F., Li, D., 2012. Provenance andtectonic setting of the Carboniferous sedimentary rocks of the East JunggarBasin, China: evidence from geochemistry and U–Pb zircon geochronology.Gondwana Research. http://dx.doi.org/10.1016/j.gr.2011.11.001.

Yin, J., Yuan, C., Sun, M., Long, X., Zhao, G., Wong, K.P., Geng, H., Cai, K., 2010. LateCarboniferous high-Mg dioritic dikes in Western Junggar, NW China:geochemical features, petrogenesis and tectonic implications. GondwanaResearch 17, 145–152.

Yuan, H.L., Wu, F.Y., Gao, S., 2003. Determination of U–Pb age and rare earthelement concentration of zircons from Cenozoic intrusions in northeasternChina by laser ablation ICP-MS. Chinese Science Bulletin 48, 2411–2421.

Yuan, C., Sun, M., Long, X.P., Xia, X.P., Xiao, W.J., Li, X.H., Lin, S.F., Cai, K.D., 2007a.Constraining the deposition time and tectonic background of the Habahe Groupof the Altaid. Acta Petrologica Sinica 23, 1635–1644 (in Chinese with Englishabstract).

Yuan, C., Sun, M., Xiao, W.J., Li, X.H., Chen, H.L., Lin, S.F., Xia, X.P., Long, X.P., 2007b.Accretionary orogenesis of the Chinese Altai: insights from Paleozoic granitoids.Chemical Geology 242, 22–39.

Yuan, C., Sun, M., Wilde, S., Xiao, W.J., Xu, Y.G., Long, X.P., Zhao, G.C., 2010. Post-collisional plutons in the Balikun area, East Chinese Tianshan: evolvingmagmatism in response to extension and slab break-off. Lithos 119, 269–288.

Zhang, L.F., Ai, Y.L., Li, X.P., Rubatto, D., Song, B., Williams, S., Song, S.G., Ellis, D., Liu,J.G., 2007. Triassic collision in western Tianshan orogenic belt, China: evidencefrom SHRIMP U–Pb dating of zircon from HP/UHP eclogitic rocks. Lithos 96,266–280.

Zhang, Z.C., Mao, J.W., Cai, J.H., Kusky, T.M., Zhou, G., Yan, S.H., Zhao, L., 2008a.Geochemistry of picrites and associated lavas of a Devonian island arc in thenorthern Junggar terrane, Xinjiang (NW China): implications for petrogenesis,arc mantle sources and tectonic setting. Lithos 105, 379–395.

Zhang, C.L., Li, X.H., Li, Z.X., Ye, H.M., Li, C.N., 2008b. A Permian layered intrusivecomplex in the western Tarim Block, northwestern China: product of a ca. 275Ma mantle plume? Journal of Geology 116, 112–128.

Zhang, C.L., Li, Z.X., Li, X.H., Xu, Y.G., Zhou, G., Ye, H.M., 2010a. A Permian largeigneous province in Tarim and Central Asian Orogenic Blet (CAOB), NW China:results of a ca. 275 Ma mantle plume? GSA Bulletin. http://dx.doi.org/10.1130/B30007.1.

http://dx.doi.org/10.1007/s00410-009-0485-3

http://dx.doi.org/10.1007/s00531-008-0407



http://dx.doi.org/10.1130/B30007.1

http://dx.doi.org/10.1130/B30007.1


Zhang, C.L., Xu, Y.G., Li, Z.X., Wang, H.Y., Ye, H.M., 2010b. Diverse Permianmagmatism in the Tarim Block, NW China: genetically linked to the PermianTarim mantle plume? Lithos 119, 537–552.

Zhang, J., Xiao, W., Han, C., Ao, S., Yuan, C., Sun, M., Geng, H., Zhao, G., Guo, Q., Ma, C.,2011. Kinematics and age constraints of deformation in a Late Carboniferousaccretionary complex in Western Junggar, NW China. Gondwana Research 19,958–974.

Zhou, M.F., Lesher, C.M., Yang, Z.X., Li, J.W., Sun, M., 2004. Geochemistry andpetrogenesis of 270 Ma Ni–Cu–(PGE) sulfide-bearing mafic intrusions in theHuangshan district; Eastern Xinjiang; Northwest China: implications for thetectonic evolution of the Central Asian Orogenic Belt. Chemical Geology 209,233–257.

Zhou, G., Zhang, Z.C., He, B., Wang, X., 2006. Zircon SHRIMP U-Pb age and its tectonicimplications of the gneiss granite in Mayinebo fault. Chinese Geology 33, 13–20(in Chinese with English abstract).

Zhou, G., Zhang, Z.C., Wang, X., Luo, S.B., He, B., Zhang, X.L., 2007. Zircon U–PbSHRIMP and 40Ar–39Ar Dating of the Granitic Mylonite in the Mayinebo FaultBelt of North Xinjiang and its geological significance. Acta Geologica Sinica 81,359–369 (in Chinese with English abstract).

Zhou, G., Wu, X.G., Dong, L.H., Zhang, Z.C., 2009a. Formation time and geochemicalfeature of the Wutubulak pluton in the northeastern margin of Junggar inXinjiang and its geological significance. Acta Geologica Sinica 25, 1390–1402 (inChinese with English abstract).

Zhou, M.F., Zhao, J.H., Jiang, C.Y., Gao, J.F., Wang, W., Yang, S.H., 2009b. OIB-like,heterogeneous mantle sources of Permian basaltic magmatism in the westernTarim Basin, NW China: implications for a possible Permian large igneousprovince. Lithos 113, 583–594.

Revisiting the “Irtish tectonic belt”: Implications for the Paleozoic tectonic evolution of the...

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