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SCIENCE CHINA Earth Sciences, Volume 61, Issue 10: 1419-1439(2018) https://doi.org/10.1007/s11430-017-9215-3

Subdivision and age of the Yanchang Formation and the Middle/Upper Triassic boundary in Ordos Basin, North China

Shenghui DENG1,2,3,*, Yuanzheng LU1,2,3, Zhong LUO1,2,3, Ru FAN1,2,3, Xin LI1,2,3, Yi ZHAO4, Xueying MA1,2,3, Rukai ZHU1,2,3, Jingwei CUI1,2,3
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  • ReceivedJun 2, 2017
  • AcceptedApr 18, 2018
  • PublishedJul 24, 2018

Abstract

The Yanchang Formation is extensively developed in the Ordos Basin and its surrounding regions. As one of the best terrestrial Triassic sequences in China and the major oil-gas bearing formations in the Ordos Basin, its age determination and stratigraphic assignment are important in geological survey and oil-gas exploration. It had been attributed to the Late Triassic and regarded as the typical representative of the Upper Triassic in northern China for a long time, although some scholars had already proposed that the lower part of this formation should be of the Middle Triassic age in the mid-late 20th century. In this paper, we suggest that the lower and middle parts of the Yanchang Formation should be of the Ladinian and the bottom possibly belongs to the late Anisian of the Middle Triassic, mainly based on new fossils found in it and high resolution radiometric dating results. The main source rocks, namely the oil shales and mudstones of the Chang-7, are of the Ladinian Age. The upper part of the Yanchang Formation, namely the Chang-6 and the above parts, belongs to the Late Triassic. The uppermost of the Triassic is missed in most parts of the Ordos Basin. The Middle-Upper Triassic Series boundary lies in the Yanchang Formation, equivalent to the boundary between Chang-7 and Chang-6. The Ladinian is an important palaeoenvironmental turning point in the Ordos Basin. Palaeoenvironmental changes in the basin are coincidence with that of the Sichuan Basin and the main tectonic movement of the Qinling Mountains. It indicates that tectonic activities of the Qinling Mountains are related to the big palaeoenvironmental changes in both the Ordos and Sichuan Basins, which are caused by the same structural dynamic system during the Ladinian.


Acknowledgment

We are deeply grateful for Prof. Meng Fansong from Wuhan Center of Geological Surrey and Prof. Gregory J. Retallack of Oregon University of the United States for their help on identifications of some plant fossils. We also would like to thank Prof. Yu Bingsong and Dr. Ruan Zhuang from China University of Geosciences (Beijing) who participated some field investigations and the two anonymous reviewers who carefully reviewed the manuscript and provided many constructive comments and suggestions. ID-TIMS zircon U-Pb analysis was carried out in Beijing Research Institute of Uranium Geology. This study was jointly supported by PetroChina Basic Research Programs (Grant Nos. 2011A-0206, 2014A-0216) and the National Basic Research Program of China (Grant No. 2014CB239001).


References

[1] BGMRSP (Bureau of Geology and Mineral Resources of Shaanxi Province). 1989. Regional Geology of Shaanxi Province. Beijing: Geological Publishing House. 637. Google Scholar

[2] BGMRSP (Bureau of Geology and Mineral Resources of Shaanxi Province). 1998. Stratigraphy (Lithostratic) of Shaaxi Province. Wuhan: China University of Geosciences Press. 281. Google Scholar

[3] Blackburn T J, Olsen P E, Bowring S A, McLean N M, Kent D V, Puffer J, McHone G, Rasbury E T, Et-Touhami M. Zircon U-Pb geochronology links the end-Triassic extinction with the Central Atlantic Magmatic Province. Science, 2013, 340: 941-945 CrossRef PubMed ADS Google Scholar

[4] Brack P, Rieber H, Nicora A, Mundil R. 2005. The Global boundary stratotype section and point (GSSP) of the Ladinian Stage (Middle Triassic) at Bagolino (Southern Alps, Northern Italy) and its implications for the Triassic time scale. Episodes, 28: 233–244. Google Scholar

[5] Brack P, Rieber H, Nicora A. 2003. The global stratigraphic section and point (GSSP) for the base of the Ladinian Stage (Middle Triassic). A proposal for the GSSP at the base of the Curionii Zone in the Bagolino section (Southern Alps, Northern Italy). Albertiana, 28: 13–25. Google Scholar

[6] Brick M I. 1952. Flora fossil and stratigraphy of lower Mesozoic deposits of the central Ilek River in western Kazachastan. Trudy Geologiskhaya Instituta Nauchotekhniskoi Akademia Nauk, SSSR., 9: 3–73. Google Scholar

[7] Chen A Q, Chen H D, Hou M C, Lou Z H, Xu S L, Li J, Su Z T. 2011. The Middle-Late Triassic event sediments in Ordos Basin: Indicators for Episode I of the Indosinian Movement. Acta Geol Sin, 85: 1681–1689. Google Scholar

[8] Cheng Z W. 1980. Vertebrate fossils. In: IGCAGS, ed. Mesozoic Stratigraphy and Palaeontology of Ordos Basin (2). Beijing: Geological Publishing House. 115–173. Google Scholar

[9] Dang B, Zhao H, Li W H, Chen Y S, Zheng X J, Yan Z Q, Jia Y Q. 2007. Identification of sequence boundaries of different orders in the Upper Triassic Yanchang Formation in northern Shaanxi, Ordos Basin. Geol China, 34: 414–421. Google Scholar

[10] Deng S H, Cheng X S, Qi X F, Luo Z J. 2000. Plant fossils from the Upper Triassic and the Lower Jurassic of Junggar Basin, Xinjiang, Northwest China. In: Editorial Committee of the Proceedings of the Third National Stratigraphical Conference of China, ed. Proceedings of the Third National Stratigraphical Conference of China. Beijing: Geological Publishing House. 174–178. Google Scholar

[11] Deng S H, Lu Y Z, Fan R, Pan, Y H, Cheng X S, Fu G B, Wang Q F, Pan H Z, Shen Y B, Wang Y Q, Zhang H C, Jia C K, Duan W Z, Fang L H. 2010. The Jurassic System of Northern Xinjiang, China. Hefei: University of Science and Technology of China Press. 279. Google Scholar

[12] Deng X Q, Li W H, Liu X S, Pang J L, Liu X. 2009. Discussion on the stratigraphic boundary between Middle Triassic and Upper Triassic. Acta Geol Sin, 83: 1089–1096. Google Scholar

[13] Deng X Q, Lin F X, Liu X Y, Pang J L, Lü J W, Li S X, Liu X. 2008. Discussion on relationship between sedimentary evolution of the Triassic Yanchang Formation and the Early Indosinian Movement in Ordos Basin. J Palaeogeogr, 10: 159–166. Google Scholar

[14] Dobruskina I A. 1985. Correlation of the Lower Triassic plant-bearing beds of Siberia and China. Albertiana, 3: 21–23. Google Scholar

[15] Fliche P. 1910. Flore fossil du Trias en Lorrain et France-Comte. Bull Soc Sci Nancy, 11: 222–286. Google Scholar

[16] Fu J H, Guo Z Q, Deng X Q. 2005. Sedimentary facies of the Yanchang Formation of Upper Triassic and petroleum geological implication in southwestern Ordos Basin. J Palaeogeogr, 7: 34–44. Google Scholar

[17] Fu Q, Lü M M, Liu Y D. 2008. Developmental characteristics of Turbidite and its implication on petroleum geology in Late Triassic Ordos Basin. Acta Sediment Sin, 26: 186–192. Google Scholar

[18] Fu Q, Sun X T, Liu Y D. 2009. Geologic significance and re-establishment of basin character in Late Triassic of Ordos Basin. J Tongji Uni (Nat Sci), 37: 1537–1540. Google Scholar

[19] Fu Z Y, Yuan X Q. 1998. Late Triassic sporopollen assemblage from Liupanshan Basin of Ningxia and their stratigraphical significance. Acta Palaeont Sin, 37: 446–455. Google Scholar

[20] Grauvogel-Stamm L, Duringer P. 1983. Annalepis zeilleri Fliche 1910 emend., un organe reproducteur de Lycophyte de la Lettenkohle de l′Est de la France. Morphologie, spores in situ et paléoécologie. Geolo Rundschau, 72: 23–51. Google Scholar

[21] Grauvogel-Stamm L, Lugardon B. The Triassic lycopsids Pleuromeia and Annalepis: Relationships, evolution, and origin. Am Fern J, 2001, 91: 115-149 CrossRef Google Scholar

[22] Guo X Q, Yan Z, Wang Z Q, Wang T, Wu F F, Fu C L, Hou K J, Li J L. 2011. Geological characteristics and associated magmatic ages of the Xiekeng skarn-type Cu-Au deposit in the West Qinling terrane. Acta Petrol Sin, 27: 3811–3822. Google Scholar

[23] Han P, Feng S B, Li X M, Wang K L, Yuan X Q, He J, Hu A P. 2014. Geological evidence of “the Archaic Uplift” Late Triassic in western margin of Ordos Basin and Identification of Original Boundary in the West of Basin. J Oil Gas Techn, 36: 1–5. Google Scholar

[24] Harris T M. 1937. The fossil flora of Scoresby Sound, East Greenland. Part 5: Stratigraphic relations of the plant beds. Medd om Grønland, 112: 1–114. Google Scholar

[25] He J, Feng S B, Yuan X Q, Han P, Xie G W, Zhang C L. 2011. Sandstone component of outcrops of Yanchang Formation in the margin of Ordos Basin and its geological significance. Lithol Reserv, 23: 30–43. Google Scholar

[26] He Y, Yue Z L. 1987. Triassic Foraminifera from Maantang of Jiangyou, Sichuan. Bull. Nanjing Inst Geol Palaeont, Acad Sin, 12: 191–230. Google Scholar

[27] He Z X. 2003. The Evolution History and Its Oil and Gas Resources in Ordos Basin. Beijing: Petroleum Industry Press. 1-390. Google Scholar

[28] Heer O. 1877. Flora fossilis Helvetiae: Die vorweltliche flora der Schweiz. Zurich: J Wurster & Co. 182. Google Scholar

[29] Hsü R, Zhu J N, Chen Y, Duan S Y, Hu Y F, Zhu W Q. 1979. Late Triassic Baoding flora, SW Sichuan. Beijing: Science Press. 130. Google Scholar

[30] Huang Z G, Zhou H Q. 1980. Palaeobotany. In: IGCAGS, ed. Mesozoic Stratigraphy and Palaeontology of Ordos Basin (1). Beijing: Geological Publishing House. 43–114. Google Scholar

[31] IGCAGS (Institute of Geology, Chinese Academy of Geological Sciences). 1980. Mesozoic Stratigraphy and Palaeontology of Ordos Basin. Beijing: Geological Publishing House. 212. Google Scholar

[32] Ji L M, Wu T, Li L T. 2006. Paleoclimatic characteristics during sedimentary period of main source rocks of Yanchang Formation (Triassic) in Eastern Gansu. Acta Sedment Sin, 24: 426–431. Google Scholar

[33] Jiang D X, Wang Y D, Wei J. 2006. Palynoflora and its environmental significance of the Late Triassic in Tongchuan, Shaanxi Province. J Palaeogeogr, 8: 23–33. Google Scholar

[34] Jin W J, Zhang Q, He D F, Jia X Q. 2005. SHRIMP dating of adakites in western Qinling and their implications. Acta Petrol Sin, 21: 959–966. Google Scholar

[35] Kelber K P. 1990. Die versunkene Pflanzenwelt aus den Deltasümpfen Mainfrankens vor 230 Millionen Jahren. Beringeria, 1: 1–67. Google Scholar

[36] Krasser F. 1900. Die von W. A. Obrutschew in China und Centralasien 1893–1894 gesammelten fossilen Pflanzen. Debkschr K Akad Wiss Wien. Ser Mat-Nat, 70: 1–15. Google Scholar

[37] Kustatscher E, Kelber K P, van Konijnenburg-van Cittert J H A. Danaeopsis Heer ex Schimper 1869 and its European Triassic species. Rev Palaeobot Palynology, 2012, 183: 32-49 CrossRef Google Scholar

[38] Lai X L, Yin H F, Yang F Q. 1995. Reconstruction of the Qinling Triassic Paleo-ocean. Earth Science, 20: 648–656. Google Scholar

[39] Lehrmann D J, Ramezani J, Bowring S A, Martin M W, Montgomery P, Enos P, Payne J L, Orchard M J, Hongmei W, Jiayong W. Timing of recovery from the end-Permian extinction: Geochronologic and biostratigraphic constraints from south China. Geology, 2006, 34: 1053-1056 CrossRef ADS Google Scholar

[40] Lei Z Y, Zhang C J, Yang X P. 2000. Division and distribution of petroleum system in Ordos Basin. Petrol Expl, 5: 75–82. Google Scholar

[41] Li D, Dong S, Deng S. New knowledge of the Upper Triassic in Liupanshan Basin, Ningxia, China. Chin Sci Bull, 1998, 43: 1100-1107 CrossRef ADS Google Scholar

[42] Li D S. 2004. Return to petroleum geology of Ordos Basin. Petrol Explor Dev, 31: 1–7. Google Scholar

[43] Li J L, Wu X, Zhang F. 2008. The Chinese Fossil Reptiles and their Kin. 2nd ed. Beijing: Science Press. 473. Google Scholar

[44] Li J, Chen H D, Lin L B, Zhao J X, Chen A Q, Zhu Z J, Peng C L, Zhang C G, Chen Y Q. 2010. Effect of ancient earthquake and its geological significance of Upper Triassic Yanchang Formation in Southeast Ordos Basin. Geol Rev, 56: 480–489. Google Scholar

[45] Li Y, Yao J X, Wang S E, Pang Q Q. 2016. Middle-Late Triassic terrestrial strata and establishment of stages in the Ordos Basin. Acta Geosci Sin, 37: 267–276. Google Scholar

[46] Li Z H, Feng S B, Yuan X Q, Qu H J. 2014. Chronology and its significance of the Lower Jurassic tuff in Ordos Basin and its periphery. Oil Gas Geol, 35: 729–741. Google Scholar

[47] Liu B P, Li Z S. 1980. Bivalvia fossils. In: IGCAGS, ed. Mesozoic Stratigraphy and Palaeontology of Ordos Basin (2). Beijing: Geological Publishing House. 1–47. Google Scholar

[48] Liu H Q, Li X B, Chen Q L, Wan Y R, Guo Y R, Liao J B. 2013. Analysis of Some Petroleum Geological Problems of Yanchang Formation in Ordos Basin. Beijing: Science Press. 169. Google Scholar

[49] Liu J, Abdala F. 2015. New discoveries from the Sinokannemeyeria-Shansisuchus Assemblage Zone: 2. A new species of Nothogomphodon (Therapsida: Therocephalia) from the Ermaying Formation (Anisian, Middle Triassic) of Shanxi, China. Vert PalAsiat, 53: 123–132. Google Scholar

[50] Liu J, Li L, Li X W. 2013. SHRIMP U-Pb zircon dating of the Triassic Ermaying and Tongchuan formations in Shanxi, China and its stratigraphic implications. Vert PalAsiat, 51: 162–168. Google Scholar

[51] Liu J, Ramezani J, Li L, Shang Q H, Xu G H, Wang Y Y, Yang J S. 2017. High-precision temporal calibration of Middle Triassic vertebrate biostratigraphy: U-Pb zircon constraints for the Sinokannemeyeria fauna and Yonghesuchus. Vert PalAsiat, 55: 1–9. Google Scholar

[52] Liu J, Sullivan C. 2017. New discoveries from the Sinokannemeyeria-Shansisuchus Assemblage Zone: 3. Archosauriformes from Linxian, Shanxi, China. Vert PalAsiat, 55: 107–125. Google Scholar

[53] Liu J, Wu X C, Li J L. 2001. The first reptile from the Tongchuan Formation and its stratigraphical significance. Vert PalAsiat, 39: 67–71. Google Scholar

[54] Liu J. 2015. New discoveries from the Sinokannemeyeria-Shansisuchus Assemblage Zone: 1. Kannemeyeriiformes from Shanxi, China. Vert PalAsiat, 53: 16–28. Google Scholar

[55] Liu S F, Zhang G W. 2008. Evolution and geodynamics of basin/mountain systems in East Qinling-Dabieshan and its adjacent regions, China. Geol Bull China, 27: 1943–1960. Google Scholar

[56] Liu X T. 1962. Two new hybodus from North Shensi, China. Vert PalAsiat, 6: 150–156. Google Scholar

[57] Liu Z S, Shang Y K, Li W B. 1981. Triassic and Jurassic sporo-pollen assemblages from some localities of Shaanxi and Gansu, North-west China. Bull Nanjing Inst Geol Palaeont, Acad Sin, 3: 131–210. Google Scholar

[58] Luo B J, Zhang H F, Xiao Z Q. 2012. Petrogenesis and tectonic implications of the Early Indosinian Meiwu pluton in West Qinling, central China. Earth Sci Front, 19: 199–213. Google Scholar

[59] Mader D. 1990. Palaeoecology of the flora in Buntsandstein and Keuper in the Triassic of Middle Europe. Stuttgart: Gustav Fischer Verlag, 1582. Google Scholar

[60] Meng F S, Li X B. 2002. Declension and survival strategy of the Middle Triassic Pleuromeia in the Yangtze valley. Geol Min Res South China, 2: 60–65. Google Scholar

[61] Meng F S, Zhang Z L, Niu Z J, Chen D Y. 2000. Primitive Lycopsid flora in the Yangtze valley of China and Systematics and Evolution of Isoetales. Changsha: Hunan Science and Technology Press. 87. Google Scholar

[62] Meng F S. 1993. The discovery of Pleuromeia in South China and its significances. Chin Sci Bull, 38: 1686–1688. Google Scholar

[63] Meng F S. 1998. Studies on Annalepis from Middle Triassic along the Yangtze river and its bearing on the origin of Isoetes. Acta Bot Sin, 40: 1–7. Google Scholar

[64] Miao S J. 1983. Middle Triassic spores and pollen from Hongdong county, Shanxi Province. Bull Tianjin Inst Geol Min Res, 6: 161–170. Google Scholar

[65] Moisan P, Voigt S. Lycopsids from the Madygen Lagerstätte (Middle to Late Triassic, Kyrgyzstan, Central Asia). Rev Palaeobot Palynol, 2013, 192: 42-64 CrossRef Google Scholar

[66] Mundil R, Ludwig K R, Metcalfe I, Renne P R. Age and Timing of the Permian Mass Extinctions: U/Pb Dating of closed-system zircons. Science, 2004, 305: 1760-1763 CrossRef PubMed ADS Google Scholar

[67] Oliver D. 1873. Hooker’s Icones Plantarum. Vol. 12. London: Longman, Rees, Orme, Brown, Green, & Longman. 62–63. Google Scholar

[68] Pálfy J, Parrish R R, David K, Vörös A. 2003. Mid–Triassic integrated U-Pb geochronology and ammonoid biochronology from the Balaton Highland (Hungary). J Geol Soc, 160: 271–284. Google Scholar

[69] P’an C H. 1934. The oil shale deposits of Northern Shensi. Bull Geol Surv China, 24: 33–46. Google Scholar

[70] P’an, C H. 1936. Older Mesozoic plants from North Shensi. Palaeont Sin Ser A, 4: 1–49. Google Scholar

[71] Pattemore G A, Rigby J F, Playford G. The Mesozoic megafossil genus Linguifolium Arber 1917. Acta Palaeobotanica, 2015, 55: 123-147 CrossRef Google Scholar

[72] Qiu X W, Liu C Y, Li Y H, Mao G Z, Wang J Q. 2009. Distribution characteristics and geological significances of tuff interlayers in Yanchang Formation of Ordos Basin. Acta Sediment Sin, 27: 1138–1146. Google Scholar

[73] Qu H J, Yang X C, Cao J Z, Fan Y H, Guan L Q. 2011. Oil accumulation rules in deep zones of Upper Triassic Yanchang Formation in Ordos Basin. Acta Petrol Sin, 32: 243–248. Google Scholar

[74] Qu L F, Yang J D, Bai Y H, Zhang Z L. 1983. A preliminary discussion on the characteristics and stratigraphic divisions of Triassic spores and pollen in China. Bull. Chin. Acad Geol Sci, 5: 81–94. Google Scholar

[75] Qu L F, Zhang W P, Yu J X. 1987. The progress of Mesozoic palynology in thirty years. In: editorial committee of Professional papers of stratigraphy and palaeontology Chinese Academy of Geological Sciences, ed. Professional Papers of Stratigraphy and Palaeontology, 17. Beijing: Geological Publishing House. 29–55. Google Scholar

[76] Qu L F. 1980. Triassic spores and pollen. In: IGCAGS, ed. Mesozoic Stratigraphy and Palaeontology of Ordos Basin (1). Beijing: Geological Publishing House. 115–204. Google Scholar

[77] Qu L F. 1982. The palynological assemblage from the Liujiagou Formation of Jiaocheng, Shanxi. Bull Inst Geol Chin Acad Geol Sci, 4: 83–93. Google Scholar

[78] Retallack G. The life and times of a Triassic lycopod. Alcheringa, 1975, 1: 3-29 CrossRef Google Scholar

[79] Retallack G J. Middle triassic megafossil plants and trace fossils from Tank Gully, Canterbury, New Zealand. J R Soc New Zealand, 1980, 10: 31-63 CrossRef Google Scholar

[80] Sadovnikov G N. 1982. The morphology, systematics and distribution of the genus Tomiostrobus. Palaeont J, 16: 100–109. Google Scholar

[81] Shaanxi Stratigraphic Chart Writing Group. 1983. Shaanxi Fascicule of Regional Stratigraphic Chart of Northwest China. Beijing: Geological Publishing House. 255. Google Scholar

[82] Shen S, Crowley J L, Wang Y, Bowring S A, Erwin D H, Sadler P M, Cao C, Rothman D H, Henderson C M, Ramezani J, Zhang H, Shen Y, Wang X, Wang W, Mu L, Li W, Tang Y, Liu X, Liu L, Zeng Y, Jiang Y, Jin Y. Calibrating the End-Permian mass extinction. Science, 2011, 334: 1367-1372 CrossRef PubMed ADS Google Scholar

[83] Shi X, Zhang W, Yu J X, Chu D L, Huang C. 2014. The flora from Karamay Formation in the South and North of Tianshan Mountain, Xinjiang. Geol Sci Tech Inf, 33: 61–66. Google Scholar

[84] Su D Y, Li Y G, Pang Q Q, Chen S E. 1980. Ostracod fossils. In: IGCAGS, ed. Mesozoic Stratigraphy and Palaeontology of Ordos Basin (2). Beijing: Geological Publishing House. 48–83. Google Scholar

[85] Su D Z. 1999. A new palaeoniscoid fish from The Upper Triassic of Zichang, Northern Shanxi. Vert PalAsiat, 37: 257–266. Google Scholar

[86] Su D Z.1984. A new palaeoniscoid fish from the Yanchang group of north Shaanxi and its biostratigraphic significance. Vert PalAsiat, 22: 261–265. Google Scholar

[87] Sun A L. 1980. Late Permian and Triassic terrestrial tetrapods of North China. Vert PalAsiat., 18: 100–110. Google Scholar

[88] Swisher C C, Wang Y Q, Wang X L, Xu X, Wang Y. Cretaceous age for the feathered dinosaurs of Liaoning, China. Nature, 1999, 400: 58-61 CrossRef ADS Google Scholar

[89] Sze H C, Chow T Y. 1962. Mesozoic Continental Deposits of China. Beijing: Science Press. 180. Google Scholar

[90] Sze H C, Lee X X. 1951. Notes on a Rhaetic species Danaeopsis fecunda Halle from the Yenchang Formation of Kansu. Sci Rec, 4: 85–91. Google Scholar

[91] Sze H C. 1956a. Older Mesozoic plants from the Yancheng Formation, Northern Shensi. Palaeont Sin New Ser, 5: 1–217. Google Scholar

[92] Sze H C. 1956b. On the occurrence of the Yanchang Formation in Guyuan district, Gansu Province. Acta Palaeont Sin, 4: 285–292. Google Scholar

[93] Wang C Y. 1993. Triassic conodont biostratigraphy in China. J Stratigr, 15: 307, 311–312. Google Scholar

[94] Wang D Y, Xin B S, Yang H, Fu J H, Yao J L, Zhang Y. 2014. Zircon SHRIMP U-Pb age and geological implications of tuff at the bottom of Chang-7 of Yanchang Formation in the Ordos Basin. Sci China Earth Sci, 44: 2160–2171. Google Scholar

[95] Wang F, Tian J C, Fan L Y, Chen R, Qiu J L. 2010. Evolution of sedimentary fillings in Triassic Yanchang Formation and its response to Indosinian Movement in Ordos Basin. Nat Gas Geosci, 21: 882–889. Google Scholar

[96] Wang L X, Xie Z M, Wang Z Q. 1978. On the occurrence of Pleuromeia from the Qinshui Basin in Shanxi Province. Acta Palaeont Sin, 17: 195–211. Google Scholar

[97] Wang S E, Liu S W. 1980. Conchostraca fossils. In: IGCAGS, ed. Mesozoic Stratigraphy and Palaeontology of Ordos Basin (2). Beijing: Geological Publishing House. 84–110. Google Scholar

[98] Wang X F. 1977. On the New genus of Annularia-like plants from the Upper Triassic in Sichuan-Shanxi area. Acta Palaeont Sin, 16: 185-190. Google Scholar

[99] Wang X F. 1984. A supplement of Mesozoic plants from Hebei. In: Tianjin Institute of Geology and Mineral Rescurces, ed. Palaeontological Atlas of North China, II. Mesozoic. Beijing: Geological Publishing House. 297–302. Google Scholar

[100] Wang Y D, Jiang D X, Xie X P. 2003. Late Triassic palynoflora and its environmental significance of Tuweihe, Shaanxi. Acta Sediment Sin, 21: 434–440. Google Scholar

[101] Wang Z H, Dai J Y. 1981. Triassic conodonts from the Jianngyou-Beichuan area, Sichuan Province. Acta Palaeont Sin, 20: 138–152. Google Scholar

[102] Wang Z Q, Lou Y Y. 1990. Studies on the megaspores of a mid-Triassic lycopsid in Shaanxi, China. Acta Bot Sin, 32: 397–403. Google Scholar

[103] Wang Z Q, Wang L X. 1982. A new species of the Lycopsida Pleuromeia from the Early Triassic of Shanxi, China, and its ecology. Palaeontology, 25: 215–225. Google Scholar

[104] Wang Z Q. 1984. Plant kingdom. In: Tianjin Institute of Geology and Mineral Resources, ed. Palaeontological Atlas of North China, II. Mesozoic. Beijing: Geological Publishing House. 224–302. Google Scholar

[105] Wu F L, Li W H, Li Y H, Xi S L. 2004. Delta sediments and evolution of the Yanchang Formation of Upper Triassic in Ordos Basin. J Palaeogeogr, 6: 307–315. Google Scholar

[106] Wu X C, Liu J, Li J L. 2001. The anatomy of the first archosauriform (Diapsida) from the terrestrial Upper Triassic of China. Vert PalAsiat, 39: 251–265. Google Scholar

[107] Xia Q S, Tian J C. 2007. Characteristics and geological significance of Seismites of the Yanchang Formation, Upper Triassic, Ordos Basin. Acta Sediment Sin, 25: 246–252. Google Scholar

[108] Xin B S, Yang H, Fu J H, Wang D Y, Yao J L, Zhang Y, Zuo B. 2013a. SHRIMP U-Pb Zircon Age and Its Stratigraphic Significance of Tuff at the Bottom of the Upper Triassic Nanying’er Group, Mount Baoji Area, Jingyuan County, Gansu Province. Geol Rev, 59: 267–273. Google Scholar

[109] Xin B S, Yang H, Wang D Y, Fu J H, Yao J L, Luo A X, Zhang Y. 2013b. SHRIMP U-Pb age and its stratigraphic significance of tuff at the Baojishan Area, Jingyuan County, Gansu Province. Adv Earth Sci, 28: 1043–1048. Google Scholar

[110] Yang B H, Bai H Q, Dai Y Q, Zha L, Li J, Jin W Q, Liu X J. 2008. Provenance and depositional systems during the depositional period of interval 8 of Upper Triassic Yanchang Formation in Qingyang area, Ordos Basin. J Palaeogeogr, 10: 251–259. Google Scholar

[111] Yang H, Deng X Q. 2013. Deposition of Yanchang Formation deep-water sandstone under the control of tectonic events, Ordos Basin. Petrol Explor Dev, 40: 513–520. Google Scholar

[112] Yang H, Fu J H, Yuan X Q. 2011. Atlas of Geological Section of the Western Ordos Basin and the Surrounding Areas. Beijing: Petroleum Industry Press. 541. Google Scholar

[113] Yang H, Fu Q, Qi Y L, Zhou X P, Gong N, Huang S X. 2016. The paleontology phase zones and its geological significance on the Late Triassic Yanchang Stage palaeo-lacustrine Ordos Basin. Acta Sediment Sin, 34: 688–693. Google Scholar

[114] Yang J X. 2002. Tectonic Evolution and Oil-gas Reservoirs Distribution in Ordos Basin. Beijing: Petroleum Industry Press. 228. Google Scholar

[115] Yang Y Y. 2004. Influence of Qinling Orogenic Movements in Indo-Chinese Epoch to sedimentary characteristics of Yanchang Formation in Ordos Basin. Coal Geol Explor, 32: 7–9. Google Scholar

[116] Yang Z J. 1961. On a new cynodont from NW Shansi. Vert PalAsiat, 3: 109–113. Google Scholar

[117] Yang Z Y, Zhang S X, Yang J D, Zhou H Q, Cao H S. 2000. Stratigraphic Code of China: The Triassic. Beijing: Geological Publishing House. 139. Google Scholar

[118] Ye M N. 1979. On some Middle Triassic plants from Hupeh and SzeChuan. Acta Palaeont Sin, 18: 73–82. Google Scholar

[119] Yin H F. 1982. Discussion on the Lainian stage in China. Geol Rev, 28: 236–239. Google Scholar

[120] Yong T S. 1984. Discussion on the age of Yanchang Group in Ordos Basin. Xinjiang Petrol Geol, 1: 58–60. Google Scholar

[121] Yu J, Broutin J, Huang Q, Grauvogel-Stamm L. Annalepis, a pioneering lycopsid genus in the recovery of the Triassic land flora in South China. Comptes Rendus Palevol, 2010, 9: 479-486 CrossRef Google Scholar

[122] Yu J X, Huang Q S, Broutin J, Yang F Q. 2008. The early Early Triassic Annalepis from western Guizhou and eastern Yunnan, South China. Acta Palaeont Sin, 7: 292–300. Google Scholar

[123] Zhang F L. 2004. Relation of multicycles to oil and natural gas in the Ordos Basin. Exp Petrol Geol, 26(2): 138–142, 152. Google Scholar

[124] Zhang G W, Cheng S Y, Guo A L, Dong Y P, Lai S C, Yao A P. 2004. Mianlue paleo-suture on the southern margin of the Central Orogenic System in Qinling-Dabie-with a discussion of the assembly of the main part of the continent of China. Geol Bull China, 23: 846–853. Google Scholar

[125] Zhang G W, Zhang B R, Yuan X C, Xiao Q H. 2001. Qinling Orogenic Belt and Continental Dynamics. Beijing: Science Press. 855. Google Scholar

[126] Zhang H, Peng P A, Zhang W Z. 2014. Zircon U-Pb ages and Hf isotope characterization and their geological significance of Chang 7 tuff of Yanchang Formation in Ordos Basin. Acta Petrol Sin, 30: 565–575. Google Scholar

[127] Zhang W Z, Yang H, Peng P A, Yang Y H, Zhang H, Shi X H. 2009. The influence of late Triassic volcanism on the development of Chang 7 high grade hydrocarbon source rock in Ordos Basin. Geochimica, 38: 573–582. Google Scholar

[128] Zhang Z H, Fu Z Y, Luo K Q, Geng G C. 1982. The Mesozoic palynological assemblage in northern Ordos Basin. In: Palynological society of China, ed. The Symposium of the First Academic Conference of Palynological Society of China. Beijing: Science Press. 116–124. Google Scholar

[129] Zhao W Z, Wang X M, Guo Y R, Liu H Q, Bai Y L. 2006. Restoration and tectonic reworking of the Late Triassic basin in western Ordos Basin. Petrol Explor Dev, 33: 6–13. Google Scholar

[130] Zheng L D, Yao J X, Tong Y B, Song B, Wang L T, Yang Z Y. 2010. Ziron U-Pb dating for the boundary of Olenekian-Anisian at Wangmo, Guizhou Province. Acta Geol Sin, 84: 1112–1117. Google Scholar

[131] Zhong X C. 1964. Upper Triassic and Middle Jurassic ostracod fossils from the Odors Basin. Acta Palaeont Sin, 12: 426–447. Google Scholar

[132] Zhou X, He S, Chen Z Y, Liu P, Wang F R. 2016. Characteristics and controlling factors of source rocks in Yanchang Formation sequence framework, Ordos Basin. Earth Sci, 41: 1055–1066. Google Scholar

[133] Zou C N, Zhu R K, Cui J W, Deng S H, Luo Z, Lu Y Z, Qiu Z. 2018. High-precision dating and geological significance of Chang 7 tuff zircon of the Triassic Yanchang Formation, Ordos Basin in central China. J Palaeogeogr, in press. Google Scholar

  • Figure 1

    Comprehensive stratigraphic column of the Yanchang Formation in the Ordos Basin.

  • Figure 2

    Outcrops of the Yanchang Formation in the Ordos Basin. (a) Sandstone intercalated with mudstone of Chang-8, Yaochanggou section, Longxian, Shaanxi Province, containing plant fossils, such as Annalepis sp., Linguifolium sp.; (b) Tuff bed intercalated in mudstone at the lower of Chang-7, Ruihe section, Chongxin, Gansu Province; (c) Mudstone intercalated with thin tuff bed at lower of Chang-7, Yaoqu section, Yaoxian, Shaanxi Province, yielding plant fossils, including Pleuromeia sp., Annalepis zeilleri; (d) Oil shale intercalated with numerous tuff seams of Chang-7, Yaoqu section, Yaoxian, Shaanxi Province; (e) Boundary between the Yanchang Formation and the Jurassic, An′kou section, Huating, Gansu Province, arrows showing position of plant fossils Danaeopsis fecunda and Symopteris zeilleri; (f) Mudstone of Chang-4+5, intercalated with a thin tuff bed (arrow), Ruihe section, Chongxin, Gansu Province.

  • Figure 3

    Some newly discovered plant fossils from the Yanchang Formation. (a)–(c) Annalepis sp., (d)–(e) Annalepis zeilleri, (f) Linguifolium sp., (g) Pleuromeia sp., (h) Danaeopsis fecunda, (i) Symopteris zeilleri. (a)–(c), (f) From the Chang-8 of the Yaochanggou section, Longxian, Shaanxi; (d), (e), (g) from the lower part of the Chang-7 of the Yaoqu section, Yaoxian, Shaanxi; (h)–(i) from the uppermost part of the Yanchang Formation of Ankou, Huating, Gansu. Scale bar = 1 cm.

  • Figure 4

    Typical elements of the palynoflora from the Yanchang Formation. 1. Sphagnumsporites sp., from the middle and upper part of the Yaoshan Formation of the Yaoshan section in Tongxin; 2. Waltzispora sp., from the middle and lower part of the Yaoshan Formation of the Mahuanggou section in Zhongwei; 3. Triquitrites sp., from the Chang-7 of the Yaochanggou section in Longxian; 4. Concavisporites sp., from the Chang-7 of the Shanshuihe section in Xunyi; 5. Apiculatisporis sp., from the Chang-8 of the Yaochanggou section in Longxian; 6. Lophotriletes sp., from the Chang-4+5 of the Ankou section in Chongxin; 7. Dictyophyllidites sp., from the Chang-7 of the Yaochanggou section in Longxian; 8. Annulisporaperforatus, from the middle and upper part of the Yaoshan Formation of the Yaoshan section in Tongxin; 9. Limatulasporites sp., from the top of the Yanchang Formation of the Qishuihe section in Tongchuan; 10. Aratrisporitesminimus, from the Chang-7 of the Yaochanggou section in Longxian; 11. Angiopteridaspora sp., from the Chang-7 of the Yaochanggou section in Longxian; 12. Leiotriletes sp., from the middle and upper part of the Yaoshan Formation of the Yaoshan section in Tongxin; 13. Punctatisporites sp., from the Chang-7 of the Yaochanggou section in Longxian; 14. Annulisporamicroannulata, from the lower part of the Yanchang Formation of the Shangjiayuan section in Huating; 15. Retusotriletes sp., from the middle and upper part of the Yaoshan Formation of the Yaoshan section in Tongxin; 16. Kraeuselisporites sp., from the Chang-1 of the Ankou section in Chongxin; 17. Kyrtomisporis sp., from the Chang-9 of the Shiwanghe section in Yichuan; 18. Cyathidites sp., from the Chang-1 of the Ankou section in Chongxin; 19. Asseretospora sp., from the middle part of the Yaoshan Formation of the Yaoshan section in Tongxin; 20. Lundbladispora sp., from the Chang-4+5 of the Ankou section in Chongxin; 21. Triquitritesincises, from the middle part of the Nanying′er Formation of the Dongqinggou section in Jingtai; 22. Calamospora sp., from the top of the Yanchang Formation of the Qishuihe section in Tongchuan; 23. Aratrisporitesfischeri, from the middle and upper part of the Yaoshan Formation of the Yaoshan section in Tongxin; 24. Striatoabieites sp., from the Chang-7 of the Yaochanggou section in Longxian; 25. Lueckisporites sp., from the top of the Yanchang Formation of the Qishuihe section in Tongchuan; 26. Caytonipollenitespallidus, from the Chang-7 of the Yaochanggou section in Longxian; 27. Klausipollenites sp., from the Chang-7 of the Shanshuihe section in Xunyi; 28. Verrucosisporites sp., from the Chang-8 of the Yaochanggou section in Longxian; 29. Aratrisporitespalettae, from the Dingjiayao Formation of the Dongqinggou section in Jingtai; 30. Cordaitinagunnyalensis, from the Chang-8 of the Ankou section in Chongxin; 31. Protohaploxypinus sp., from the Chang-3 of the Ankou section in Chongxin; 32. Taeniaesporites sp., from the top of the Yanchang Formation of the Qishuihe section in Tongchuan; 33. Chordasporites sp., from the Chang-7 of the Shanshuihe section in Xunyi; 34. Parataeniaesporitespseudostriatus, from the Chang-7 of the Yaochanggou section in Longxian; 35. Florinites sp., from the Chang-4+5 of the Ankou section in Chongxin.

  • Figure 5

    Concordia diagram (right) and individual 206Pb/238U ages (ranked by their uncertainties) of zircon analyses from tuff layers of the Yanchang Formation in the Ordos Basin.

  • Table 1   Brief evolution of subdivision of the Triassic System in the Ordos Basin

    Gan K W. 1959. Preliminary study report on the strata of the Sinian to Jurassic in the North and Northwest of the Ordos Platform. unpublished. b) Xie Q Y, Sun G F, Li Y L. 1974. Report on the general petroleum geological investigations in the Shaanxi-Gansu-Ningxia Basin. unpublished.

  • Table 2   Comparison of the Middle and Late Triassic flora in northern China

  • Table 3   Global chronostratigraphic subdivision of the Triassic and ages for its boundaries

    Chronostratigraphy

    Boundary age (Ma)

    Source

    Jurassic

    Lower

    Hettangian

    201.3±0.2

    North America (Blackburn et al., 2013)

    Triassic

    Upper

    Rhaetian

    208.5

    Inferred

    Norian

    227

    Inferred

    Carnian

    237

    Inferred

    Middle

    Ladinian

    242

    Italy and Hungary (Brack, 2003)

    Anisian

    247.2

    Guizhou, China (Lehrmann et al. , 2006; Zheng et al., 2010)

    Lower

    Olenekian

    251.2

    Inferred

    Induan

    252.17±0.06

    South China (Shen et al., 2011)

    Permian

    Upper

    Changhsingian

     

    Based on International Commission on Stratigraphy. 2017.

  • Table 4   Zircon dating data of the Yanchang Formation and coeval strata in the Ordos Basin and its Periphery

    No.

    Section

    Horizon

    Method

    Lab

    Result (Ma)

    Reference

    1

    Well Zheng 8 in Zhengning of Shaanxi

    Chang-7 oil shale

    LA-ICPMS U-Pb

    State Key Laboratory of ContinentalDynamics, Northwest University, China

    242–220

    220–205

    Zhang et al., 2009

    2

    ? (not provided in original paper)

    Base of Chang-7

    LA-ICPMS U-Pb

    State Key Laboratory of ContinentalDynamics, Northwest University, China

    228.2±2.0

    Yang and Deng, 2013

    3

    ? (not provided in original paper)

    Middle-upper of Chang-7

    LA-ICPMS U-Pb

    State Key Laboratory of ContinentalDynamics, Northwest University, China

    221.8±2.0

    Yang and Deng, 2013

    4

    Well Ning-36 in Xunyi of Shaanxi

    Chang-7 oil shale

    LA-ICPMS U-Pb

    State Key Laboratory of ContinentalDynamics, Northwest University, China

    236.1±2.7

    Zhang et al., 2014

    5

    Well Zheng-8 in Xunyi of Shaanxi

    Chang-7 oil shale

    LA-ICPMS U-Pb

    State Key Laboratory of ContinentalDynamics, Northwest University, China

    234.3±2.8

    Zhang et al., 2014

    6

    Well Zheng-9 in Xunyi of Shaanxi

    Chang-7 oil shale

    LA-ICPMS U-Pb

    State Key Laboratory of ContinentalDynamics, Northwest University, China

    234.19±2.6

    Zhang et al., 2014

    7

    Jiaokou in Yonghe, Shanxi

    Upper Tongchuan Fm.

    SHRIMP U-Pb

    Beijing SHRIMP Center

    238.6±2.6

    Liu et al., 2013

    8

    Sangbi in Yonghe, Shanxi

    Upper Tongchuan Fm.

    SHRIMP U-Pb

    Beijing SHRIMP Center

    234.6±6.5

    Liu et al., 2013

    9

    Baojishan in Jingyuan, Gansu

    Base of Nanying’er Fm.

    SHRIMP U-Pb

    Beijing SHRIMP Center

    244.1±3.8

    Xin et al., 2013a

    10

    Wangjiashan in Jingyuan, Gansu

    Base of Nanying’er Fm.

    SHRIMP U-Pb

    Curtin University of Technology, WesternAustralia

    244.9±2.8

    Xin et al., 2013b

    11

    Well Beiluo-36 in Huan County, Gansu

    Base of Chang-7

    SHRIMP U-Pb

    Beijing SHRIMP Center

    241.3±2.4

    Wang et al., 2014

    12

    Well Beizhuang-211 in Xifeng, Gansu

    Base of Chang-7

    SHRIMP U-Pb

    Beijing SHRIMP Center

    239.7±1.7

    Wang et al., 2014

    13

    Sangbi in Yonghe, Shanxi

    Upper Tongchuan Fm.

    ID-TIMS

    MIT, USA

    241.482

    Liu et al., 2017

    14

    Jiaokou in Yonghe, Shanxi

    Upper Tongchuan Fm.

    ID-TIMS

    MIT, USA

    241.369

    Liu et al., 2017

    15

    Yaoqu in Tongchuan, Shaanxi

    Lower Chang-7

    ID-TIMS

    MIT, USA

    241.06±0.12

    241.558±0.093

    Zou et al., 2018

    16

    Ruishuihe in Chongxin, Gansu

    Lower-middle Chang-7

    ID-TIMS

    Beijing Research Institute of Uranium Geology

    239.0±1.8

    This paper

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