| 西藏措勤盆地的地层学研究进展及上二叠统—侏罗系地层序列的厘定 |
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| 关键词:Tibet Coqen Basin Upper Permian Triassic Jurassic |
| 基金项目:国家自然科学基金项目(编号: 41472030);科技基础性工作专项(编号: 2015FY310100);中国地质调查局基础性公益性矿产地质调查项目(编号: DD20160120-02; DD20160120-04; DD20160126);中国地质科学院基本科研业务费项目(编号: J1607) |
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| 摘要: |
| Stratigraphic Progress of the Coqen Basin and Redefinition of the Upper Permian–Jurassic Stratigraphic Sequence |
| In this paper, the authors made a brief summarization of the stratigraphic progress in the study of Coqen Basin and its adjacent areas. Based on the lots of field geological survey and indoor palaeontology identification and research in recent years, the authors and their research team obtained some new discovery. Upper Permian–Jurassic stratigraphic sequence was redefined, in combination with previous stratigraphy results and data in the study area. The Upper Permian rocks in Coqen Basin could be divided into limestone represented by Wenbudangsan Formation and dolomite indicated by Mujiucuo Formation. The Triassic stratigraphic successions have two types, formed respectively in shelf facies and carbonate platform facies. The shelf facies consists of the Lower Triassic Garencuo Formation, the Middle Triassic to Upper Triassic Carnian Zhulong Formation, the Upper Triassic Norian Jiangrang Formation, and the Upper Triassic Rhaetian to the Lower Jurassic Dibucuo Formation, whereas the carbonate platform facies comprises of the Lower Triassic Mujiucuo Formation, the unnamed Middle Triassic unit, the Upper Triassic Norian Mailonggang Formation and the Upper Triassic Rhaetian to the Lower Jurassic Quehala Formation. It is difficult to distinguish in detail the Lower Jurassic from the Upper Triassic Rhaetian strata at present. The Middle Jurassic sediments are characterized by the mudstones interbedded with basic-ultrabasic rocks, reflecting a deep sea or semi-deep sea facies. The Upper Jurassic strata comprise the Sabozhibule Formation and Tukari Formation in upward succession. No Tithonian fossils have been found yet, so there seems to have a sedimentary gap between the Lower Cretaceous Duoni Formation and the Tukari Formation. From the newly recognized Upper Permian to Jurassic successions, the authors found that Coqen Basin was in carbonate platform environments in three periods, respectively in the Late Permian to Early Triassic, Late Triassic Norian, and Late Jurassic Oxfordian to Kimmeridgian. In addition, there existed two tectonic extension events, which occurred in Middle Triassic and Middle Jurassic, and two tectonic uplifting events that happened at the end of the Late Triassic Norian and the end of late Jurassic Kimmeridgian period. These repeated tectonic extension and uplifting events directly caused the rise and fall of the sea level, leading to the vertical superposition of deep-water and shallow-water sedimentary facies. The formed sedimentary assemblages under this background were favorable for the hydrocarbon accumulation. It is necessary to strengthen the paleostratigraphic work to improve the research on the Upper Permian to Jurassic successions in the future. |
| JI Zhan-sheng,YAO Jian-xin,WU Gui-chun,SUN Qian,SHI Qiu-yuan,HE Ji-fu,LI Hao,LIU Zhen-yu,GUO An-chen,HOU Zhao-shuo,LI Dong-ze.2018.Stratigraphic Progress of the Coqen Basin and Redefinition of the Upper Permian–Jurassic Stratigraphic Sequence[J].Acta Geoscientica Sinica,39(4):401-407. |
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