川西南晚奥陶世五峰期岩相古地理  

Lithofacies palaeogeography in Late Ordovician Wufeng Age in southwestern Sichuan

作　　者：牟传龙[1,2] 葛祥英[1,2] 周恳恳[1,2] 王秀平[1,2,3] 

机构地区：[1]国土资源部沉积盆地与油气资源重点实验室,四川成都610081 [2]成都地质矿产研究所,四川成都610081 [3]山东科技大学,山东青岛266590

出　　处：《中国地质》2015年第1期192-198,共7页Geology in China

基　　金：国家重大科技专项(2011ZX05043-005);中国地质调查局项目(1212010916060);中石化南方分公司页岩气资源评价项目联合资助

摘　　要：通过对川西南汉源—马边—雷波地区典型剖面上奥陶统五峰组沉积岩性特征、充填序列、沉积构造及室内分析等研究,并结合研究区晚奥陶世构造特征,将川西南地区五峰期分为2期,划分为潮坪、浅水陆棚和深水陆棚3种沉积相。指出在晚奥陶世五峰早期,受加里东构造运动影响,扬子与华夏陆块发生构造挤压碰撞,川中、黔中等边缘隆起抬升扩大,上扬子地区由克拉通海相盆地转为被隆起围限的隆后盆地,除川中隆起、川西—滇中隆起周缘沉积潮坪相白云质页岩、泥灰岩和白云质灰岩外,川西南绝大部分面积主要发育深水陆棚相炭质页岩和硅质页岩、含炭粉砂质页岩。五峰晚期,伴随着全球性冰期事件的发生,研究区乃至整个上扬子区发生大规模海退,大面积的深水陆棚相转为浅水陆棚沉积,岩性主要为粉砂质页岩、泥灰岩、钙质炭质页岩和硅质灰岩等,较前期钙质成分明显增多。According to the lithological characteristics, filling sequences, sedimentary structures and lab analysis of Late 0rdovician Wufeng Formation, combined with the structural features, the authors divided the Wufeng Age in southwestern Sichuan into two periods, and the southwestern Sichuan can be divided into tidal- fiat facies and deep shelf and shallow shelf facies. In the Late Ordovician early Wufeng Age, affected by the Caledonian Movement and the continuous extrusion and collision between Yangtzeand Cathaysia blocks, the Central Sichuan and Guizhou were increasingly uplifted, and the Upper Yangtze region was submerged and transformed into carbonate ramp, and finally developed into the back-bulge basin confined by the marginal uplifts. Tidal fiat facies were developed around Central Suchuan and Western Sichuan-Central Yuiman uplifts with dolomitic shales, muddy limestones and dolomitic limestones. Large areas of westem Sichuan developed deep shelf facies which deposited carbonaceous shales, siliceous and carbonaceous- silty shales. In the late Wufeng Age of Late Ordovician, with the emergence of the worldwide glacial event, large- scale regression started in the study area and even in the whole Upper Yangtze area, shallow shelf facies replaced deep shelf facies with silty shales, muddy limestones, calcareous-carbonaceous shales and siliceous limestones, and they had more calcium in comparison with those in former periods.

关 键 词：川西南 晚奥陶世五峰期 沉积相 岩相古地理 

分 类 号：P531[天文地球—古生物学与地层学]