Palaeogeography, Palaeoclimatology, Palaeoecology 441 (2016) 516–527

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Palaeogeography, Palaeoclimatology, Palaeoecology

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Late Cretaceous biostratigraphy and sea-level change in the southwestTarim Basin

Dangpeng Xi a,⁎, Wenxin Cao a, Yi Cheng a, Tian Jiang b, Jianzhong Jia c, Yuanhui Li a, Xiaoqiao Wan a

a State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Xueyuanlu 29, Haidian District, Beijing 100083, Chinab College of Zijin Mining, Fuzhou University, Fuzhou, Fujian 350108, Chinac Research Institute, China National Offshore Oil Corporation, Taiyanggong Nanjie NO 6, Chaoyang District, Beijing 100083, China

⁎ Corresponding author.E-mail address: xdp1121@163.com (D. Xi).

http://dx.doi.org/10.1016/j.palaeo.2015.09.0450031-0182/© 2015 Elsevier B.V. All rights reserved.

a b s t r a c t

a r t i c l e i n f o

Article history:Received 1 March 2015Received in revised form 10 September 2015Accepted 21 September 2015Available online 21 October 2015

Keywords:CretaceousTarim BasinBiostratigraphySea levelPaleoenvironment

TheUpper Cretaceous sediments of the southwest TarimBasin include the remnants of a large epicontinental sea.In this study, based on the analyses of sedimentation, foraminifera, ostracods, bivalves, and other fossils from theSimuhana Section, aswell as published biostratigraphy data,we present a field-based biostratigraphy and reviewof sea-level change for the Upper Cretaceous strata in the southwest Tarim Basin. The Upper Cretaceous marinestrata include the Kukebai and Dongba formations. Relatively abundant foraminifera, ostracods, and bivalveswere discovered and identified. Based on the biostratigraphy and correlation, the proposed age of the Lowerand Middle Kukebai Formation is Cenomanian to earliest Turonian; the Upper Kukebai is of Turonian to earlyConiacian age. The Lower Dongba Formation is late Coniacian to early Campanian, the Middle Dongba Formationis late Campanian to early Maastrichtian, and the Upper Dongba Formation is late Maastrichtian in age, possiblyextending into the Danian. The relative sea level began to rise during sedimentation of the Lower Kukebai Forma-tion (Cenomanian), and reached a maximum by the time of the middle to upper part of the Upper Kukebai For-mation (Turonian to early Coniacian). After a subsequent sea level fall, another transgression began duringsedimentation of the Middle Dongba Formation. Above the Upper Dongba Formation, the sea level fell dramati-cally. The sea level of the southwest Tarim Basin shows a close relationship with the global sea level curve, andwith the sea level of south Tibet.

© 2015 Elsevier B.V. All rights reserved.

1. Introduction

During the Cretaceous Period, the existence of enhanced greenhouseconditions and high sea level are generally accepted (Huber et al., 2000;Skelton, 2003; Hu et al., 2012). The global Cretaceous sea level and thelevel of the western and eastern Tethys Sea have been widely studied(Haq et al., 1987; Haq, 2014; Wan, 1992; Zhang, 2000; Wang et al.,2005; Miller et al., 2005; Cloetingh and Haq, 2015). The Late Cretaceousto Paleogene sediments of the southwest (SW) Tarim Basin in westernChina include the remnants of a large epicontinental sea (Tang et al.,1992; Bosboom et al., 2011). During that period of global rise in sealevel and tectonic forcing, the Neo-Tethys covered the SW Tarim Basin(Late Cretaceous to Paleogene). The Paleogene sediments of the SWTarim Basin have been recently studied in detail (Bosboom et al.,2011; Sun and Jiang, 2013; Wang et al., 2014). Though the biostratigra-phy and sedimentation of Cretaceous marine strata have been the sub-ject of much work (Hao et al., 1982, 2001; Mao and Norris, 1988; Tanget al., 1989, 1992; Zhong, 1992; Lan and Wei, 1995; Yang et al., 1995;Jiang et al., 1995; Guo, 1990, 1995), the Late Cretaceous biostratigraphyand sea level are still not perfectly understood. The SW Tarim can help

us to understand the level of the epicontinental sea, and thepaleoenvironment of the northwest Tethys.

This paper presents a field-based biostratigraphy and sea-level ofUpper Cretaceous strata in the SW Tarim Basin. The aim of the studywas to provide a stratigraphic framework, by which to assess and dis-cuss the relative evolution of the Late Cretaceous sea level, in thestudy area.

2. Geological setting

2.1. Tectonics and stratigraphy

The Tarim Basin is a large Mesozoic–Cenozoic composite inlandbasin, superimposed upon a Paleozoic platform (Zhou, 2001). It is situ-ated south of the Tianshan Mountains (Tianshan Mts.) and north of theWest KunlunMoutain (KunlunMts.) and AltunMountain (Fig. 1A). Theareal extent of the basin is 560,000 km2, and the basin is part of a rela-tively undeformed crustal block within the India–Asia collision system(Yin and Harrison, 2000). The Tarim is a poly history superimposedbasin that has seven evolutionary stages: (1) Sinian–Cambrian–Ordovician aulacogen stage, (2) Silurian–Devonian intracratonicdepression stage, (3) Carboniferous marginal sea stage, (4) Permianrift-basin stage, (5) Triassic–Jurassic foreland basin stage,

Fig. 1. Topography of the Western Tarim Basin (A, modified from Sun and Jiang, 2013) and geological map of the study area (B, modified from He et al., 2004).

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(6) Cretaceous–Paleogene Neo-Tethys bay stage, and (7) Neogene–Pleistocene foreland and inland basin stage (Li et al., 2004).

The SWTarimBasin is located between theWest KunlunMts. (PamirMountains) and the Tianshan Mts. (Fig. 1). It sits on the southwest partof the basinwith an area of 121 300 km2 (Jia, 1997). The SWTarimBasinpresents a continuous stratigraphic sequence deposited since the Juras-sic to the present (Tang et al., 1989; Hao et al., 2001; Jia et al., 2004). Thepaleogeography of the SW Tarim can be divided into the Tianshan Mts.and Kunlun Mts. (Tang et al., 1992). The Mesozoic SW Tarim Basin iscomposed of a non-marine sequence below (Jurassic Shalitashen,Kangsu, Yangye, Taerga, Kuzigongsu formations, Lower CretaceousKezilesu Group) and marine sequence above (Upper CretaceousKukebai, Dongba (Wuyitake, Yigeziya, Tuyiluoke) formations), whilethe Cenozoic SW Tarim Basin consists of a marine sequence below(Aertashi, Qimugen, Kalatar, Wulagen, and Bashibulake formations)and a continental sequence above (Keziluoyi, Anjuan, Pakabulake andArtushi formations) (Fig. 2; Hao et al., 1982; Zhou, 2001; Yin et al.,2002).

The Upper Jurassic Kuzigongsu Formation is characterized by lami-nated gray–white sandstone and mudstone with coal beds and abun-dant non-marine plant fossils (Zhou, 2001). It is overlain by the LowerCretaceous Kezilesu Group, which contains reddish and white sand-stone. The Upper Cretaceous assemblages include the Kukebai andDongba formations in the Tianshan Mts. area, and the Kukebai,Wuyitake, Yigeziya, and Tuyiluoke formations in the Kunlun Mts. area(Fig. 2). The Kukebai Formation is subdivided into three members. Thelower one is dominated by purple–red mudstone with intercalatedthin gypsum layers, while the middle and upper parts are made up ofgray–green mudstone with abundant marine fossils (Tang et al., 1989;Hao et al., 2001). The Dongba Formation, conformably overlying theKukebai Formation, is subdivided into three members. The lower andupper ones consist of red mudstone with intercalated thin gypsumrock, and themiddle part ismade up of carbonate and gray–greenmud-stone with abundant marine fossils (Tang et al., 1989).

2.2. The study section

The study area is located in the Tianshan Mts. area of the SW TarimBasin. Cretaceous sediments are well exposed along the Kezilesu River(Fig. 1B). The Simuhana Section is situated in Simuhana Village ofWuqia County, and crops out along the Kezilesu River (Fig. 3). Themea-sured section contains Cretaceous to Cenozoic strata. The Simuhana sec-tion includes two separated sections: Simuhana Section 1 located alongthe south bank of the Kezilsu River (39°43′36.92″ N; 73°59′38.03″ E),and Simuhana Section 2 along the north bank of the Kezilesu River(39°43′44.92″ N; 73°59′39.29″ E). Section 1 includes the Kezilesu

Group, Lower and middle Kukebai Formation, and Section 2 includesthe Upper Kukebai Formation and Dongba Formation. This work wascarried out in theUpper CretaceousKukebai Formation andDongba For-mation (Wuyitage, Yigeziya and Keziluoyi formations).

3. Material and methods

About 100microfossil and bivalve fossil sampleswere collected from193.2m thickness of the Simuhana section. Samples of 100 g dryweightwere dispersed inwater for severalweeks prior to sieving through a 200microns sieve. Ostracods and foraminifera were picked from the sam-ples under a low-power binocular microscope. Microfossil and bivalvestudies were carried out at the micropaleontological laboratory of theChina University of Geosciences (Beijing).

4. Lithostratigraphy

4.1. Kukebai Formation

The lower Kukebai Formation (51.9 m) is divided into eight beds(Fig. 4A). The first bed (1.1 m) is composed of gray coarse to mediumsandstonewith parallel bedding and cross bedding (Fig. 4C). The secondbed (7.8m) is composed of brown red siltymudstone, with intercalatedgray green mudstone and gypsum layers (0.5–1 cm for each layer). Thehorizontal bedding appears at the top of this bed. The third bed (1.8 m)is mainly composed of gray green mudstone, with horizontal beddingand intercalated thin gypsum layers upwards. The fourth bed (15.1 m)is composed of brown red mudstone and silty mudstone, with interca-lated gray–green mudstone and a great many thin gypsum layers. Thefifth bed (8.6 m) is composed of gray–green mudstone and, silty mud-stone, with intercalated purple red mudstone and gypsum layers.Brown yellow siltstone and silty mudstone appeared at the top of thisbed (Figs. 4D, 5A). The sixth bed (7 m) is composed of bioclastic lime-stone (Fig. 4D). Abundant bivalves, gastropods, and other biological de-bris were found in this unit (Figs. 4C, 5B). The seventh bed (3 m) iscomposed of intercalated calcareous shale, with relatively abundant os-tracod fossils (Fig. 5C). The eighth bed (7.5 m) is composed of bioclasticlimestone and calcirudite. Besides relatively abundant bivalves and gas-tropods, some gravel stone (0.2–1 cm) appeared at the top of thelimestone.

The Middle Kukebai Formation (29.9 m) can be divided into threebeds (Fig. 4B). Thefirst unit (9.3m) ismade upof dark gray–greenmud-stone with intercalated silty mudstone (Fig. 5C). Two thin shelly layershave been found in this bed. The secondbed (0.2m) ismade up of shellylayer, which is mainly composed of bivalve. The third bed (18 m) ismade up of dark gray–green mudstone, with more thin shelly layers.

Fig. 2. Mesozonic and Cenozoic stratigraphic frame in the southwest Tarim Basin (Modified from Hao et al., 1982, 2001; Tang et al., 1992; Zhou, 2001).

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The fourth bed (2.4 m) is composed of bioclastic limestone intercalatedwith gray–green mudstone, and contains abundant bivalve (Fig. 4E).

The Upper Kukebai Formation (47.5 m) can also be divided into fivebeds. The first bed (25.7 m) is composed of dark gray–green mudstonewith horizontal layers (Fig. 4E). Several thin shelly layers and thin gyp-sum beds appeared upwards. Compared with the lower and middleKukebai Formations, more fossils (e.g., bivalves, gastropods, foraminif-era, ostracods, fish teeth, and calcareous nannofossil) have been foundin this bed. The second bed (0.2 m) is composed of gray–white shellybeds, which mainly includes bivalves. The third bed (15.4 m) is com-posed of dark gray–green mudstone with abundant shelly beds. Abun-dant bivalve, gastropod, foraminifera, ostracods, and calcareousnannofossils were discovered in this bed. The fourth bed (3.2 m) is

composed of gray–green calcareous siltstone and argillaceous siltstone(Fig. 5 F). Only a few agglutinated foraminifera were discovered in thisbed. The fifth bed (3 m) is composed of gray–green layered calcareousmudstone, with intercalated thin siltstone. At the top of this bed, graymudstone interbedded with red mudstone appeared (Fig. 4 F). Nofossils were discovered in this bed.

4.2. Dongba Formation

The Lower Dongba Formation (Wuyitage Formation) (27.5 m) canbe divided into three beds. The first bed (3 m) is composed of purple–red siltstone and argillaceous siltstone, with intercalated gray–green ar-gillaceous siltstone and thin gypsum rock (Fig. 4B, F). Ripple marks

Fig. 3. Detailed geographic location of the study region.

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(Fig. 4G) and burrow was observed in this bed. The second bed (8.8 m)is composed of gray–green and brown–red mudstone, and argillaceoussiltstone with abundant gypsum layers (1–3 cm). The third bed(15.7m) is thick gypsum, thin gray–greenmudstone, and gypsummud-stone. No fossils were discovered in the Lower Dongba Formation.

The Middle Dongba Formation (Yigeziya Formation, 7.5 m) includesgray–green marl, bioclastic limestone and mudstone (Fig. 3H), withabundant bivalves, as well as gastropods and ostracods (Fig. 5G).

The Upper Dongba Formation (Tuyiluoke Formation) (28.9 m) is di-vided into four beds. The first bed (2.5 m) consists of red siltstone, andthe secondbed (4.5m) consists of gray–white calcareousmediumsand-stone (Fig. 5H). Abundant gypsum beds have been found in these twobeds. The third bed (10.8 m) is composed of gypsum, while the fourthbed (11.6 m) mainly consists of silty mudstone, with intercalated gyp-sum beds. No fossils were discovered in the Upper Dongba Formation.

5. Biostratigraphy and the age of the Kukebai andDongshan formations

5.1. Distribution of bivalves and microfossils

The samples of bivalve and microfossils were collected fromrepresentative marine beds throughout the Kukebai and Dongbaformations. Relatively abundant foraminifera, ostracods, bivalves,nannofossils, dinoflagellates (Table 1), and a few gastropods and fishteeth are present in the study section. Foraminifera, ostracods, and bi-valves were identified in this study (Fig. 6). For the nannofossils and di-noflagellates, the results of Mao and Norris (1988) and Hao and Su(1988) were cited in this study.

5.1.1. BivalvesThe Kukebai Formation yielded abundant bivalve fossils. The carbon-

ate of the Lower Kukebai Formation yielded the bivalves Flaventiaovalis,Ostrea oxiana, and Lima aff. subrigida. In addition, Andara sp. hasbeen identified from the lowermost sandstone of the Lower KukebaiFormation at the Bashibulake Section, SW Tarim Basin (Lan and Wei.,1995). The Middle Kukebai Formation is characterized by Ostreavatonnoides, Ostrea oxiana, and Lima aff. subrigda in the mudstone. TheUpper Kukebai Formation is characterized by Limamarrotiana,Pycnodontecostei, and Cyprimeria? paba. The Middle Dongba Formation yielded the

relatively poorly preserved bivalves Leptosolen sp. and Pholadomya sp.Compared with Tianshan Mts. area, the Kunlun Mts. area yielded veryabundant bivalves, especially rudists (Lan and Wei, 1995; Scott et al.,2010).

5.1.2. ForaminiferaIn this study, relatively abundant foraminifera were discovered in

samples from the Middle and Upper Kukebai Formation. The MiddleKukebai Formation samples only yielded agglutinated foraminiferaMigros asiatica, M. spiritensis, M. oryzanus, M. hectori, M. lobatulus, andM. sp. The Upper Kukebai Formation samples only yielded agglutinatedforaminifera Migros asiatica, M.spiritensis, M. oryzanus, M. hectori, M.lobatulus,M. guttiformis,M. sp., Yuanaia xinjianggensis, Y. sp., and the cal-careous benthic foraminifera Discorbis vensus, D. sp., Nonion sp., andCibicides sp. Although Hao et al. (2001) found the planktonic foraminif-era Archaeoglobigerina cretacea and Hedbergella planispira at theSimuhana area, no planktonic foraminifera were identified in this study.

No foraminifera were identified from the Dongba Formation at theSimuhana Section in this study. Based on the study of Simuhana andother sections in the SW Tarim Basin, Hao et al. (1982, 2001) suggestedthat the Lower Dongba Formation (Wuyitage Formation) is character-ized by the benthic foraminiferaMassilina quadrilateral, Quinqueloculinasimplex, and Quinqueloculina sp. These authors found Massilinaquadrilatera,M. planoconvexa, andQuinqueloculina simplex in theMiddleDongba Formation (Yigeziya Formation), while from the Upper DongbaFormation they described the Cibicides-Cibicidoides assemblage.

5.1.3. OstracodsCarbonate of the Lower Kukebai Formation yielded ostracod speci-

mens of Ovocytheridea sp., Pontocyprella sp., and Cytherella sp. In theMiddle Kukebai Formation a few ostracods Pontocyprella sp. andCytherella sp. were found. The Upper Kukebai Formation yieldedrelatively abundant ostracods: Ovocytheridea sp., Pontocyprella sp.,Cytherella sp., Schuleridea irina, Lexoconda sp., Bythocypris sp., andParacypris cf. princeps. The Middle Dongba Formation yielded theostracods Cythereis sp., Bronsteiniana, Pontocyprella facilis, Veeniamandelstami, Sarlatina yigeziyaensis, and Ovocytheridea sp. AlthoughHao et al. (2001) discovered a few ostracoda (Cythereis sp. andOvocytheridea sp.) in the lower Dongba Formation, no foraminiferawere identified from the Lower or Upper Dongba Formation in thisstudy.

5.1.4. Dinoflagellates and nannofossilsThe Middle Kukebai Formation yielded the dinoflagellate

Cyclonephelium brevispinatum zone, and the Upper Kukebai Forma-tion yielded the dinoflagellate Alterbidinium emulatum zone (Maoand Norris, 1988). The Middle and Upper Kukebai Formation containcalcareous nannofossils of the Quadrum gartneri zone (Hao and Su,1988).

Within the lower and middle units of the Dongba Formation(Wuyitage and Yigeziya formations) the dinoflagellate Canningia reticu-late zone was identified (Mao and Norris, 1988). In the Upper DongbaFormation (Tuyikuoke Formation), the dinoflagellate taxa Alterbidiniumsp., Kiokansium sp., Eucladiniun gambangense, Paleohystrichophoraubfusorioides, Trithyrodinium sp., and Diconodinium sp. occur (Mao andNorris, 1988).

5.2. The age of the Kukebai and Dongshan formations

5.2.1. Relative age of the Kukebai FormationThe bivalve species Flaventia ovalis of the Lower Kukebai Formation

was discovered from late Albian to early Cenomanian (Lan and Wei,1995). The ostracod assemblage Ovocytheridea bashenbulake-CytherellaWuqiaaensis-Schuleridea irinae was widely found in the Cenomaniansediments of Central Asian Ferghana Basin (Yang et al., 1995; Zhou,

Fig. 4.Photographs of the lithology identified in the outcrops of the Simuhana section: (A) LowerKukebai Formation, (B)Middle Kukebai Formation,Upper Kukebai Formation andDongbaFormation, (C) Parallel bedding of the sandstone from the Lower Kukebai Formation, (D) Bioclastic limestone of the Lower Kukebai Formation, (E) Bioclastic limestone of the MiddleKukebai Formation, (F) Redmudstone interbedwith intercalated gray–greenmudstone, the Lower Dongba Formation, (G) Ripples of the lower Dongba Formation, (H)Marl of theMiddleDongba Formation.

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2001). This puts the age of the Lower Kukebai Formation in the range ofthe early Cenomanian.

The bivalvesOstrea vatonnoides, Ostrea oxiana, and Lima aff. subrigidaof theMiddle Kukebai Formation range frommiddle to late Cenomanian(Lan and Wei, 1995). Migros spiritensis was discovered from theCenomanian Kaskapau Formation (Hao et al., 2001). The dinoflagellates

of the Cyclonephelium brevispinatum zone are likely Cenomanian toTuronian in age (Mao and Norris, 1988). In addition, based on the pres-ence of the calcareous nannoplankton species Quadrum gartneri (Haoand Su, 1988) from themiddle and upper part of theKukebai Formation,it is suggested that the age of theMiddle and Upper Kukebai Formationis Turonian to early Coniacian (Lamolda et al., 1994; Burnett, 1998; Erba,

Fig. 5.Microfacies of the Kukebai and Dongba Formations: (A) Silty mudstone, Lower Kukebai Formation, (B) Bioclastic limestone, Lower Kukebai Formation, (C) Silty mudstone, LowerKukebai Formation, (D) Muddy siltstone, Middle Kukebai Formation, (E) Mudstone, Upper Kukebai Formation, (F) Siltstone, Upper Kukebai Formation, (G) Bioclastic limestone, MiddleDongba Formation, (H) Sandstone, Upper Dongba Formation. Microphotographs at LM (light microscope).

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2004; Melinte-Dobrinescu et al., 2013a, 2013b). Hence, the relative ageof theMiddle Kukebai Formationmight bemiddle Cenomanian to earli-est Turonian.

The Upper Kukebai Formation yielded the foraminiferArchaeoglobigerina cretacea, Hedbergella planispira, H. holmdelensis, andWhiteinella inornata (Hao et al., 1982, 2001).Archaeoglobigerina cretacearanges from the Coniacian to earliest Maastrichtian, Hedbergella

planispira from Aptian to early Coniacian, H. holmdelensis fromConiacian to earliest Maastrichtian (Caron, 1985), while Whiteinellainornata is typically uppermost Cenomanian to lowermost Turonian(BouDagher-Fadel, 2012), indicating that the age of Upper Kukebai For-mation is possibly extended within Turonian to early Conician interval.The ostracod Sarlatina leguminoformiswas discovered in the Turonian toSantonian of the Tadiik and Ferghana Basin (Yang et al., 1995).

Table 1Bivalves, microfossils, and age of Kukebai and Dongba Formation.

Stratigraphy Foraminifera Ostracods Bivalves Nanofossils(Hao andSu, 1988)

Dinoflagellates (Mao and Norris, 1988) Stage

UpperDongba

Alterbidinium sp., Kiokansium sp.,Eucladiniun gambangense,Paleohystrichophoraubfusorioides,Trithyrodinium sp., Diconodinium sp.

L. Danian?—U.Maastrichtian

MiddleDongba

Cythereis sp., Bronsteiniana,Pontocyprella facilis, Veenia, Sarlatinayigeziyaensis, Ovocytheridea sp.

Leptosolen sp.,Pholadomya sp.

L. Maastrichtian—U.Campanian

LowerDongba

L. Campanian-U.Coniacian

UpperKukebai

Migrosasiatica,M.spiritensis,M. oryzanus,M. hectori,M. lobatulus,M. guttiformis,Yuanaiaxinjianggensis,Y. sp.,Discorbisvescus, D.sp.,Nonion sp.,Cibicides sp.

Ovocytheridea sp., Pontocyprella sp.,Cytherella sp., Schuleridea irinae,Loxoconcha sp., Bythocypris sp.,Paracypris cf. princeps

Lima marrotiana,Pycnodontecostei,Cyprimeria?faba

Quadrumgartnerizone

Alterbidinium emulatum Zone L.Coniacian–Tunonian

MiddleKukebai

Migrosasiatica,M.spiritensis,M. oryzanus,M. hectori,M. lobatulus,M. sp.

Pontocyprella sp., Cytherella sp. Ostrea vatonnoides,Ostrea oxiana,Lima aff. subrigida

Cyclonephelium brevispinatum Zone L. Turonian–M.Cenomanian

LowerKukebai

Ovocytheridea sp., Pontocyprella sp.,Cytherella sp.

Flaventia ovalis,Ostrea oxiana,Lima aff. subrigida

E. Cenomanian

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Dinoflagellates of the Cyclonephelium brevispinatum zone are likelyTuronian to Coniacian or Turonian to Santonian in age (Mao andNorris, 1988). The bivalve Rhynchostreon suborbiculatum was discov-ered in the Cenomanian to lower Turonian sediments of Europe(Pojarkova, 1984; Dhondt, 1985), and Corbula muschketowi in Turoniansediments of the Korobkovitrigonia darwaseana area (Pojarkova, 1984;Dhondt, 1985). Therefore, the age of the Upper Kukebai Formationmight be Turonian to early Coniacian.

5.2.2. Relative age of the Dongba FormationForaminifera of the Lower Dongba Formation (Wuyitage Formation)

are relatively abundant in the Akecheyi area, including a small amountof planktonic foraminifera, such as Hedbergella holmdelensis (Hao et al,2001). This species extended from the Coniacian to Maastrichtian(Caron, 1985). Based on the comprehensive analysis of foraminifera,Hao et al. (2001) suggested an age from the Coniacian up to Campanian.In addition, based on calcareous nannofossils, Hao and Su (1988) sug-gested that the age was not younger than mid-Campanian. Therefore,the age of the Lower Dongba Formation (Wuyitake Formation) mightbe late Coniacian to early Campanian.

Foraminifera were mainly discovered in the Middle Dongba Forma-tion (Yigeziya Formation) of theWuyitage area of the Kunlun Mts area.The identified foraminifera mainly belong to the assemblage ofQuinqueloculina-Triloculina (Hao et al., 2001) that suggestes aMaastrichtian age. The bivalve fauna of the lower and middle part ofthe Wuyitage units are inferred to be Coniacian to Campanian in age,but the rudists of the upper part of the Yigeziya Formation are consid-ered to be Maastrichtian (Lan and Wei, 1995). The age of the ostracodSarlatina longielliptica is suggested as Campanian to Maastrichtian(Yang et al., 1995). Hence, the age of the Wuyitake might be late Cam-panian to early Maastrichtian.

The age of the Upper Dongba Formation (Tuyiluoke Formation) isstill in debate. Hao et al. (1982, 2001), Tang et al. (1992), and Zhou(2001)) proposed a latest Cretaceous age, while Guo (1990, 1995)assigned this unit to the Paleogene. In samples from the Lower KeziluoyiFormation of theAertashi Section,Mao andNorris (1988) discovereddi-noflagellates including Palaeohystrichophora granulata, P. infusorioides,Spiniferites sp., and Pterospermella sp., which range from the Santonianto theMaastrichtian. Hao et al. (2001) discovered Cibicidoides succedensin the Lower Keziluoyi Formation, and Quinqueloculina, Massilinaand Spiroloculina in the Upper Keziluoyi Formation. The speciesCibicidoides succedens was discovered in Cretaceous sediments, whileQuinqueloculina, Massilina, and Spiroloculina occurred in the Paleogenesediments (Hao et al., 2001). Therefore, the Lower Keziluoyi Formationis likely late Maastrichtian, but the Upper Keziluoyi Formation perhapsranges into the early Danian.

6. Discussion

6.1. Paleoenvironment

Baed on the analysis of sedimentology, paleontology andpaleocology, the paleoenvironment of the Kuhebai and Dongba Forma-tion is discussed bellow (Fig. 7).

6.1.1. Kukebai FormationThe first bed of the Lower Kukebai Formation is composed of

sandstone,with parallel bedding and cross bedding, and includes the bi-valve Andara sp., indicating a coastal inshore facies (Lan andWei, 1995).The second to five units of the Lower Kukebai Formation are dominatedby purple to red mudstone and silty mudstone, with intercalated gray–greenmudstone and a lot of thin gypsum layers. There are a few benthicforaminifers and ostracods. Foraminifera Ammobaculites generally lived

Fig. 6. Distribution of bivalves and microfossils in the study area (L: lower, U: upper).

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in high-energy lagoons or estuarine environments (Kaminski et al.,2005), such as that of Chesapeake Bay (Murry, 2006). Foraminifera be-longing to the genusMigros have been found in shallowwater environ-ments of the Kilwa Group (Nicholas et al., 2006). The environmentmight be lagoonal to supratidal, and sea level began to rise slowly. Thesixth to eighth beds of the Lower Kukebai Formation mainly consist ofbioclastic limestone, containing relatively abundant bivalves in the car-bonate, such as Ostrea and Flaventia, which lived in the intertidal zone(Lan and Wei, 1995). It appears that the sea level was still rising, andthis environment was perhaps in the intertidal zone (Fig. 7). Relativelyabundant ostracods and calcareous shale were identified in the seventhbed, indicating a relatively deep and low energy water environment. Afew gravelstone were discovered in the calcirudite of the upper eighthbed, indicating a more shallow and high energy water environment.

During sedimentation of the Middle Kukebai Formation, speciesabundance and diversity began to increase, and the sediment changedto dark graymudstone, indicating a relatively deep-water environment.The biota is dominated by thebivalveOstrea and agglutinated foraminif-era Migros, which lived in intertidal and subtidal zone (Hao and Zeng,1984; Lan and Wei, 1995). The paleoenvironment might be intertidalto subtidal (Fig. 7). The uppermostMiddle Kukebai Formation, however,is similar to the sixth bed of the lower Kukebai Formation, which mostprobably deposited in the intertidal zone.

The Upper Kukebai Formation also contained a large number ofreefs, mainly composed of bivalves that lived far away from the coast(Lan and Wei, 1995). In addition, ammonites, echinoids, gastropods,dinoflagellates, algae, and other neritic fossils have been discovered,along with calcareous nannofossils (Zhou, 2001). The green algaePterospermella and Cymatiosphaera indicate a relatively stable neriticenvironment (He, 1991). In the Simuhana Section, the abundance anddiversity of marine fossils is very high in the middle to upper part ofthis member, including agglutinated foraminifer Migros asiatica,M.spiritensis, M. oryzanus, M. hectori, M. lobatulus, M. guttiformis, M. sp.Yuanaia xinjianggensis, and Y. sp.; the calcareous benthic foraminiferaDiscorbis vensus,D. sp.,Nonion sp., and Cibicides; as well as ostracods, bi-valves, gastropods, and fish teeth. This indicates that during depositionof the lower and middle part of the Upper Kukebai Formation,paleoenvironment gradually changed from an intertidal—subtidal envi-ronment to a normal neritic environment one (Fig. 7). However, up-wards to the uppermost part of this member, the sea level decreaseddramatically.

6.1.2. Dongba FormationDuring sedimentation of the Lower Dongba Formation, the fossil di-

versity and abundance declined significantly, while the agglutinated fo-raminifera are dominant in the microfossil assemblages. Ripples wereobserved at the bottom of this member. This finding, together withthe presence of Haplophragmium that was found in the Cretaceousnear-shore environment of western Morocco (Butt, 1982), suggest acoastal environment. Dinoflagellates were mainly discovered in thelower part of the unit, characterized by Hystrichosphaeridium, the pres-ence of which implies a turbulent, supratidal flat to lagoon environment(He, 1991). These suggest that the sea began to retreat from the SWTarim Basin (Fig. 7).

TheMiddleDongba Formation ismainly composed of carbonate sed-iments,with relatively abundant bivalves, ostracods, andgastropods, in-dicating a carbonate platform. The thickness of this is much greater inthe Kunlun Mts. area than in the Tianshan Mts. area, indicating amarginal-carbonate-platform environment in the study area. Thus, itappears that during the sedimentation of theMiddle Dongba Formation,sea level began to rise again (Fig. 7).

The Upper Dongba Formation is composed of red mudstone andsandstone with intercalated thin gypsum rock, with no fossils in thestudied section. In the KunlunMts. area, just a few benthic foraminifera,such as Cibicides, were discovered (Hao et al., 2001) suggesting a lagoonenvironment. In addition, He (1991) discovered the algal genus

Fig. 7. Upper Cretaceous stratigraphy and sea level change of the Simuhana Section.

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Fig. 8. Paleogeography of the Tarim Basin and adjacent areas (modified from Tang et al., 1992). The Upper Cretaceous marine strata are spread between the Kunlun Mts. and SouthTianshan Mts. by only 50 km in width. For the entire area between the India and Eurasia Plates, the Pamir Arc was continuously rising close to the South Tianshan Mts.

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Pediastrum, indicating an inshore environment. Hence, during deposi-tion of the Upper Dongba Formation, it appears that sea level began tofall again (Fig. 7).

6.2. 2 Late Cretaceous sea-level change in the western Tarim Basin

6.2.1. Late Cretaceous sea-level change in the study areaThe SW Tarim Basin was a typical non-marine environment during

the Jurassic (Zhou, 2001). Although it is suggested that a small seawatertransgression occurred during the Early Cretaceous, as indicated by afewmarine fossils in the Upper Kezilesu Group (Guo, 1991, a large sea-water transgression began at the time of the Lower Kukebai Formationin the Cenomanian (Hao and Zeng, 1984). The sea level began to riseduring the sedimentation of theKukebai Formation, and reached amax-imum at the time of the Upper Kukebai Formation (around 118–122 min the study section). The sea level fell again during the uppermostKukebai Formation and Lower Dongba Formation, and then began torise during the Middle Dongba Formation during the late Coniacian.After sedimentation of the Upper Dongba Formation, the sea level felldramatically. During the Late Cretaceous to Paleocene, the SW TarimBasin was a gulf, known as the Tarim Gulf (Hao and Zeng, 1984; Tanget al., 1989), an epicontinental sea environment of the northwest Te-thys. The depth and area of sea level reached a maximum in the timeof the Turonian Upper Kukebai Formation during a global sea level rise(Haq, 2014). The Upper Cretaceous marine strata are spread betweenthe Kunlun Mts. and South Tianshan Mts. by only 50 km in width. Forthe entire area between the India and Eurasia Plates, the Pamir Arc

was continuously rising close to the South Tianshan Mts. (Burtman,2000). By analyzing the lithological and sedimentological features, aswell as the macro and microfossil assemblages, it was supposed thatthe Late Cretaceous Tarim Gulf was initially at least 500 km wide atthe Pamir region (Tang et al., 1992).

6.2.2. Correlation of sea-level change during the Late CretaceousIt has been accepted that sea level was high during the Cretaceous

Period (Haq et al., 1987; Haq, 2014). It appears that sea level reachedamaximumduring the Cenomanian–Turonian, then declined gradually,and was relatively lower at the end of the Cretaceous (Fig. 9). Based onthe analysis of foraminifera and sedimentation of south Tibet, it is sug-gested that sea level rose from the Albian to the Cenomanian, reachedits peak at the Cenomanian–Turonian boundary, and then it began agradual decline, but declined dramatically at the end of Cretaceous(Fig. 6;Wan, 1992;Wang et al., 2005). In the SWTarimBasin, significantseawater transgression began during the early Cenomanian, then thesea level rose gradually, and was highest during the Turonian. The sealevel declined gradually, but there was a new rise of sea level duringthe Campanian to the earlyMaastrichtian. Therewas also a dramatic de-cline in sea level at the end of the Cretaceous. The sea level in the SWTarim Basinwas controlled by global sea level change, and can be corre-lated with the global sea level, and with sea level change in south Tibet.However, the study area was a gulf during the Late Cretaceous up toearly Paleogene interval (Hao and Zeng, 1984). The marine environ-ment was very shallow, so the sea level was also affected by regionalfactors, such as the basin sedimentary fill and the tectonic evolution of

Fig. 9. Comparison of Cenomanian up to Maastrichtian sea levels of the southwest Tarim Basin, south Tibet and the global trend.

526 D. Xi et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 441 (2016) 516–527

the Tibet, as well as the surrounding regions, such as the Tianshan Mts.and Kunlun Mts. (Jia, 1997; Zhang, 2000; Yin et al., 2002; Wang et al.,2014). (See Fig. 8.)

7. Conclusions

The Upper Cretaceous marine strata include the Kukebai andDongba formations of the Simuhana Section, which have herein beendescribed and sampled. Relatively abundant foraminifers, ostracods,and bivalves were discovered and identified.

Based on the biostratigraphy and correlation, the age of the LowerKukebai Formation is proposed to be early Cenomanian; the MiddleKukebai Formation is middle Cenomanian to earliest Turonian; andthe Upper Kukebai Formation is Turonian to early Coniacian in age.The lower Dongba Formation appears to be late Coniacian to early Cam-panian, the Middle Dongba Formation is late Campanian to earlyMaastrichtian, and the Upper Dongba Formation is late Maastrichtian,possibly extending into the Danian in age.

The sea level began to rise during sedimentation of what is now theKukebai Formation, and reached a maximum at the time of the UpperKukebai Formation. The sea level fell again during the Lower Dongba For-mation, and then began to rise during the LowerDongba Formation. Fromthere to the Upper Dongba Formation, the sea level fell dramatically. Thesea level of the southwest Tarim Basin shows a good correlation withglobal sea level fluctuation andwith the ones recorded in the south Tibet.

Acknowledgments

This study was financially supported in part by funds from theNational Basic Research Program of China (973 Program,NO.2012CB822002), the National Natural Science Foundation of China(41302008, 41172037), the State Key Laboratory of Biogeology andEnvironmental Geology (GBL215010), the Fundamental ResearchFunds for the Central Universities (No. 2652015042), and BeijingHigher

Education Young Elite Teacher Project (YETP0665). We would like tothank the following colleagues for their help: Liuqin Chen, Yang Shenfor useful suggestions for this paper; Xiaopeng Fan, Zuohuan Qin,Wenping Zhang, Qian Zhang, Zhongye Shi and Can Cui for their labora-tory assistance. This paper also benefited a lot from two anonymous re-viewers, Prof. Melinte–Dobrinescu and Prof. Michael Wagreich. Thispaper is a contribution to UNESCO-IUGS IGCP project 609 "Climate-en-vironmental deteriorations during greenhouse phases: Causes and con-sequences of short-term Cretaceous sea-level changes".

Appendix AA.1. Bivalves

Corbula muschketowi Böhm, 1911Cyprimeria faba Sowerby, 1827Flaventia ovalis Sowerby, 1827Leptosolen Conrad, 1865Lima aff. subrigida Roemer, 1836Lima marrotiana d'Orbigny,1847Ostrea oxiana Romanovskiy, 1884Ostrea vatonnoides Linne, 1758Pholadomya Sowerby, 1823Pycnodonte(Costeina) costei(Coqand), 1869Rhynchostreon suborbiculatum Lamarck, 1801

A.2. Foraminifera

Cibicides Cushman, 1927Cibicidoides succedens Brotzen, 1948Discorbis vescus Bykova, 1939Migros asiatica Bykova, 1939M.spiritensis Stelck & Wall, 1955M. oryzanus Zeng, 1982M.hectori Nauss,1947M. lobatulus Cushman & Barbat,1932

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M. guttiformis Zeng, 1982Nonion de Montfort, 1808Spiroloculina d'Orbigny,1826Quinqueloculina d'Orbigny,1826Triloculina d'Orbigny,1826Yuanaia xinjianggensis Hao and Zeng, 1984

A.3. Ostracods

Bythocypris Brady,1880Cythereis Jones, 1849Cytherella Jones,1849Cytherella cf.concavaWeaver, 1982Loxoconcha Sars, 1866Ovocytheridea Grekoff, 1951PontocyprellaMandelstam, 1963Paracypris cf. princepsMandelstam, 1963Pontocyprella facilisMandelstam, 1963Veenia mandelstami Andreev, 1965Sarlatina yigeziyaensis Yang et al., 1995Schuleridea irinae Andreev,1965

References

Burnett, J.A., 1998. Upper Cretaceous. In: Bown, P.R. (Ed.), Calcareous NannofossilsBiostratigraphyBritish Micropalaeontological Society, Publications Series. Kluwer Ac-ademic, London.

Bosboom, R.E., Dupont-Nivet, G., Houben, A.J.P., Brinkhuis, H., Villa, G., Mandic, O., Stoica,M., Zachariasse, W.J., Guo, Z.J., Li, C.X., 2011. Late Eocene sea retreat from the TarimBasin (west China) and concomitant Asian paleoenvironmental change. Palaeogeogr.Palaeoclimatol. Palaeoecol. 299, 385–398.

BouDagher-Fadel, M.K., 2012. Biostratigraphic and geological significance of planktonicForaminifers. Elsevier, Amsterdam.

Burtman, V.S., 2000. Cenozoic crustal shortening between the Pamir and Tien Shan and areconstruction of the Pamir-Tien Shan transition zone for the Cretaceous andPalaeogene. Tectonophysics 319, 69–92.

Butt, A., Micropaleontological bathymetry of the cretaceous of western Morocco.Palaeogeography, Palaeoclimatology, Palaeoecology, 37, 235-275.

Caron, M., 1985. Cretaceous planktonic foraminifera. In: Bolli, H.M., Saunders, J.M., Perch-Nielsen, K. (Eds.), Plankton Stratigraphy. Cambridge University Press, Cambridge.

Cloetingh, S., Haq, B.U., 2015. Inherited landscapes and sea level change. Science http://dx.doi.org/10.1126/science.1258375.

Dhondt, A.V., 1985. Late Cretaceous Bivalves from the A10 Exposures in Northern Aqui-taine. Cretac. Res. 6, 33–74.

Erba, E., 2004. Calcareous nannofossils and Mesozoic oceanic anoxic events. Mar.Micropaleontol. 52, 85–106.

Guo, X.P., 1990. Study on marine Cretaceous–Paleogene boundary in the western TarimBasin. Earth Sci. J. China Univ. Geosci. 15, 325–335.

Guo, X.P., 1991. An approach to the depositional environment of the Cretaceous KizilsuGroup: the lowermost marine horizon of the Cretaceous in the western TarimBasin. Acta Geol. Sin. 188–198.

Guo, X.P., 1995. Cretaceous–Paleogene foraminiferal communities from the westernTarim Basin and their Environment Significance. Acta Geosci. Sin. 1, 77–86.

Haq, B.U., Hardenbol, J., Vail, P.R., 1987. Chronology of fluctuating sea levels since the Tri-assic. Science 235, 1156–1167.

Haq, B.U., 2014. Cretaceous eustasy revisited. Glob. Planet. Chang. 113, 44–58.Hao, Y.C., Ceng, X.L., Li, H.M., 1982. Cretaceous–Paleogene stratigraphy and foraminifera of

the western Tarim Basin. Earth Sc. J. China Univ. Geosci. 2, 1–161.Hao, Y.C., Zeng, X.L., 1984. On the evolution of the west Tarim gulf from Mesozoic to Ce-

nozoic in terms of characteristics of foraminiferal fauna. Acta Micropalaeontol. Sin. 1,1–18.

Hao, Y.C., Su, X., 1988. Nannofossils of the Western Tarim Basin. Geoscience 2, 305–314.Hao, Y.C., Guo, X.P., Ye, L.S., Yao, P.Y., Fu, D.R., Li, H.M., Ruan, P.H., Wang, D.N., 2001. The

Boundary between the Marine Cretaceous and Tertiary in the Southwest TarimBasin. Geological Publishing House, Beijing.

He, C.Q., 1991. Late Cretaceous–Early Tertiary Microphytoplankton from the WesternTarim Basin in Southern Xinjiang, China. Science Press, Beijing.

He, G.Q., Cheng, S.D., Xu, X., Li, J.Y., Hao, J., 2004. An introduction to the explanatory text ofthe map of tectonics of Xinjiang and its neighbouring areas. Geological PublishingHouse, Beijing.

Hu, X.M., Wagreich, M., Yilmaz, I.O., 2012. Marine rapid environmental/climatic change inthe Cretaceous greenhouse world. Cretac. Res. 38, 1–6.

Huber, B.T., MacLeod, K.G., Wing, S.L., 2000. Warm climates in the earth history. Cam-bridge University Press, Cambridge.

Jia, C.Z., 1997. Tectonic characyeristics and petroleum, Tarim Basin, China. Petroleum in-dustry Press, Beijing.

Jia, C.Z., Zhang, S.B., Wu, S.Z., 2004. Stratigraphy of the Tarim Basin and adjacent area. Sci-ence Press, Beijing.

Jiang, X.T., Zhou, W.F., Lin, S.P., 1995. Stratigraphy and Ostracods of Xinjiang in China. Ge-ology Press, Beijing.

Kaminski, M.A., Silye, L., Kender, S., 2005. Miocene deep-water agglutinated foraminiferafrom ODP Hole 909c: Implications for the paleoceanography of the Fram Strait Area,Greenland Sea. Micropaleontology 2005 (51), 373–403.

Lamolda, M.A., Gorostidi, A., Paul, C.R.C., 1994. Quantitative estimates of calcareousnannofossil changes across the Plenus Marls (latest Cenomanian) Dover, England:implication for the generation of the Cenomanian–Turonian Boundary Event. Cretac.Res. 14, 143–164.

Lan, X., Wei, J., 1995. Late Cretaceous–Early TertiaryMarine Bivalve Fauna from theWest-ern Tarim Basin. Chinese Science Publishing House, Beijing.

Li, D.S., Liang, D.G., Jia, C.Z., Wang, G., Wu, Q.Z., He, D.F., 2004. Hydrocarbon accumulationsin the Tarim Basin, China. AAPG Bull. 80, 1587–1603.

Mao, S.Z., Norris, G., 1988. Late Cretaceous-early Tertiary dinoflagellates and acritarchsfrom the Kashi area, Tarim Basin, Xinjiang Province, China. Life Science Contributions,150. Royal Ontario Museum.

Melinte-Dobrinescu, M.C., Bernandez, E., Kaiho, K., Lamolda, M.A., 2013a. Cretaceous Oce-anic Anoxic Event 2 in the Arobes section, northern Spain: calcareous nannofossilfluctuations and isotopic events. Bojar, A.-V., Melinte-Dobrinescu, M.C., Smit, J. Geo-logical Society, London, Special Publications 382, pp. 82–98.

Miller, K.G., Kominz, M.A., Browning, J.V., Wright, J.D., Mountain, G.S., Katz, M.E.,Sugarman, P.J., Cramer, B.S., Christie-Blick, N., Pekar, S.F., 2005. The Phanerozoic re-cord of global sea-level change. Science 310, 1293–1298.

Murry, J.W., 2006. Ecology and Application of Benthic Foraminifera. Cambridge universitypress, Cambrige.

Nicholas, C.J., Pearson, P.N., Bown, P.R., 2006. Biostratigraphy and sedimentology of theUpper Cretaceous to Paleogene Kilwa Group, southern coastal Tanzania. J. Afr. EarthSci. 45, 431–466.

Pojarkova, Z.N., 1984. The Cenomanian and Turonian in Northeastern Central Asia. Cretac.Res. 5, 1–14.

Scott, R.W., Wan, X.Q., Sha, J.G., Wen, S.X., 2010. Rudists of Tibet and the Tarim basin,China: significance to Requieniidae phylogeny. J. Paleontol. 84, 444–465.

Skelton, P.W., 2003. The Cretaceous World. Cambridge University Press, London.Sun, J., Jiang, M., 2013. Eocene seawater retreat from the southwest Tarim Basin and im-

plications for early Cenozoic tectonic evolution in the Pamir Plateau. Tectonophysics588, 27–38.

Tang, T.F., Yang, H.R., Lan, X., Yu, C.L., Xue, Y.S., Zhang, Y.Y., Hu, L.Y., Zhong, S.L., 1989. Ma-rine Late Cretaceous and Early Tertiary Stratigraphy Petroleum Geology in WesternTarim Basin, China. Science Press, Beijing.

Tang, T., Xue, Y., Yu, C., 1992. Characteristics and Sedimentary Environments of the LateCretaceous to Early Tertiary Marine Strata in the Western Tarim, China. SciencePress, Beijing.

Wan, et al., 1992. Cretaceous foraminifera from the southern Tibet: a study on eustaticchange. Geoscience 6, 393–397.

Wang, C.S., Li, X.H., Hu, X.M., Wan, X.Q., Yin, J.R., Huang, Y.J., Huang, S.J., Li, G.B., 2005. Sed-imentary geology and Continental paleoceanography in Tethyan Himalaya. Geologi-cal Publishing House, Beijing.

Wang, X., Sun, D.H., Chen, F.H., Wang, F., Li, B.F., Popov, S.V., Wu, S., Zhang, Y.B., Li, Z.J.,2014. Cenozoic paleo-environmental evolution of the Pamir-Tien Shan convergencezone. J. Asia Earth Sci. 80, 84–100.

Yang, H., Jiang, X., Lin, S., 1995. Late Cretaceous–Early Tertiary Ostracod: Fauna fromWestern Tarim Basin, S. Xinjiang, China. Science Press, Beijing.

Yin, A., Harrison, T.M., 2000. Geologic evolution of the Himalayan–Tibetan orogen. Annu.Rev. Earth Planet. Sci. 28, 211–280.

Yin, A., Rumelhart, P.E., Butler, R., Cowgill, E., Harrison, T.M., Foster, D.A., Ingersoll, R.V.,Zhang, Q., Zhou, X., Wang, X., Harrison, A., Raza, A., 2002. Tectonic history of theAltyn Tagh fault system in northern Tibet inferred from Cenozoic sedimentation.Geol. Soc. Am. Bull. 114, 1257.

Zhang, K.J., 2000. Cretaceous palaeogeography of Tibet and adjacent areas (China): tec-tonic implications. Cretac. Res. 21, 23–33.

Zhong, S.L., 1992. Calcareous Nanofossils from the Upper Cretaceous and Lower Tertiaryin the Western Tarim Basin, South Xinjiang, China. Chinese Science PublishingHouse, Beijing.

Zhou, Z.Y., 2001. Tarim stratigraphy. Chinese Science Publishing House, Beijing.