| 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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| 引用本文：纪占胜,姚建新,武桂春,孙倩,石秋圆,何继富,李浩,刘振宇,郭安臣,侯召硕,李东泽.2018.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[J].地球学报,39(4):401-407. |
| DOI：10.3975/cagsb.2018.071701 |
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| 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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| 中文摘要:本文简要总结了西藏措勤盆地相关区域的地层学研究进展。近年来, 笔者及研究团队对措勤盆地及邻区进行了多次野外地质调查和室内古生物鉴定和研究, 获得了一些新的发现和认识, 在结合前人在相关地区取得的地层学成果和资料的基础上, 厘定了该地区上二叠统—侏罗系的地层序列。措勤盆地的上二叠统是以文布当桑组为代表的灰岩和以木纠错组为代表的白云岩。三叠系存在着广海陆棚相和碳酸盐岩台地两种地层序列: 前者自下而上划分为下三叠统嘎仁错组、中三叠统至上三叠统卡尼阶珠龙组、上三叠统诺利阶江让组、上三叠统瑞替阶至下侏罗统敌布错组; 后者自下而上划分为木纠错组、待建的中三叠统、上三叠统诺利阶麦隆岗组和上三叠统瑞替阶至下侏罗统的确哈拉组。下侏罗统与上三叠统瑞替阶难以区分开。中侏罗统的岩性为深海-半深海相泥岩夹有基性-超基性岩。上侏罗统自下而上划分为萨波直不勒组和吐卡日组, 目前尚未发现提唐阶的化石, 因此推测下白垩统多尼组和吐卡日组之间有沉积间断。措勤盆地在晚二叠世—早三叠世、晚三叠世诺利期和晚侏罗世牛津期—基默里奇期都处于碳酸盐岩台地环境, 冈底斯地区在中三叠世和中侏罗世发生了2期构造伸展事件, 在晚三叠世诺利期末期和晚侏罗世基默里奇期晚期发生了两次构造抬升事件。构造伸展和挤压抬升造成了海平面的反复升降变化, 导致了深水和浅水沉积相的垂向叠置, 为油气成藏创造了良好的沉积建造组合条件。上二叠统—侏罗系地层序列还有待于进一步完善, 应该加大地层古生物学的投入力度。 |
| 中文关键词:西藏 措勤盆地 上二叠统 三叠系 侏罗系 |
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| Stratigraphic Progress of the Coqen Basin and Redefinition of the Upper Permian–Jurassic Stratigraphic Sequence |
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| Abstract: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. |
| keywords:Tibet Coqen Basin Upper Permian Triassic Jurassic |
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