| 摘要: |
| 位于班公湖-怒江缝合带与雅鲁藏布江缝合带之间的措勤盆地,在中侏罗世—早白垩世期间具有以且坎-古昌-阿索裂谷带为沉积、沉降中心向南北两侧展开的古地理格局:①中晚侏罗世时期,裂谷带内由深水浊积岩、放射虫硅质岩和浅水碳酸盐岩、碎屑岩岩片及基性—超基性岩等组成;裂谷带两侧由滨浅海相碎屑岩和碳酸盐岩组成。该期盆地古地理演化具有先变深后变浅的沉积序列。②早白垩世早中期,裂谷带内仍由基性—超基性岩、深水复理石碎屑岩及放射虫硅质岩和浅水碳酸盐岩及碎屑岩组成;裂谷带两侧的日松-革吉-它日错分区主要由浅海相碎屑岩和灰岩组成;盆地南北部的措勤-申扎分区和木嘎岗日分区主要由滨岸-三角洲相碎屑岩及火山岩组成。各相带在纵向上均具有向上变深沉积序列。③早白垩世晚期,盆地以台地相碳酸盐岩沉积为主,裂谷带附近以发育台地边缘礁滩相沉积;裂谷带两侧的日松-革吉-它日错分区主要由开阔台地相灰岩组成;盆地南北部的措勤-申扎分区和木嘎岗日分区由局限台地相灰岩和陆源进积碎屑岩组成。 |
| 关键词: 措勤盆地 中侏罗世—早白垩世 沉积 西藏 |
| DOI： |
| 附件 |
| 投稿时间：2002-04-15 |
| 基金项目:国土资源部国际合作与科技司十·五重点基础研究项目“青藏高原重点沉积盆地油气资源潜力分析”(20010208)。 |
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| Sedimentary characteristics in the Coqen Basin, Xizang during the Middle Jurassic to the Early Cretaceous |
| CHEN Ming, WANG Jian, TAN Fu-wen, DU Bai-wei |
(1. Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, Sichuan, China;
2. Chengdu Institute of Geology and Mineral Resources, Chengdu 610082, Sichuan, China) |
| Abstract: |
| The Coqen Basin in Xizang lies between the Bangong-Nujiang suture zone and Yarlung Zangbo suture zone, and once extended northwards and southwards, respectively centred by the Qiekan-Goicang-Asog rift zone as the center of deposition and subsidence during the Middle Jurassic to the Early Creatceous. (1) During the Middle-Late Jurassic, the rift zone was occupied by deep-water turbidites, radiolarian siliceous rocks, shallow-water carbonate rocks, clastic rocks and basic-ultrabasic rocks, while both sides of it by littoral and shallow-marine clastic rocks and carbonate rocks. The sedimentary sequences have the features of deepening- and shallowing-upward sequences. (2) During the early and middle stages of the Early Cretaceous, the rift zone was still composed of basic-ultrabasic rocks, deep-water flysch clastic rocks, radiolarian siliceous rocks, shallow-water carbonate rocks and clastic rocks. The shallow marine clastic rocks and limestone occur in the Risum-Ge'gyai-Tarico stratigraphic subprovince, while the littoral-delta clastic rocks and volcanic rocks appear in the Coqen-Xainza stratigraphic subprovince in the south and Muggar Kangri stratigraphic subprovince in the north. All these sedimentary sequences exhibit a deepening-upward sequence. (3) During the late Early Cretaceous, the Coqen Basin was mostly covered by platform carbonate rocks, with platform-margin reefal shoal deposits developed along the rift zone. The open platform limestones are arranged in the Risum-Ge'gyai-Tarico stratigraphic subprovince, while the restricted platform limestones and terrigenous progradational clastic rocks are observed in the Coqen-Xainza stratigraphic subprovince in the south and Muggar Kangri stratigraphic subprovince in the north. |
| Key words: Coqen Basin Middle Jurassic-Early Cretaceous sedimentary sequence Xizang |
