地质论评2017，Vol.63Issue(5)：1169-1179,11.DOI:10.16509/j.georeview.2017.05.004
陕西汉中梁山二叠系乐平统底部吴家坪组王坡页岩新认识
New Petrographic and Mineralogical Analyses of the Wangpo Shale, Wujiaping Formation (Basal Lopingian, Permian) in the Liangshan Area of Shaanxi
摘要
Abstract
Objectives:The Wangpo Shale,representing Guadalupian—Lopingian Boundary (GLB) deposits,occurs at the base of the Wujiaping Formation in the Liangshan area of Shaanxi Province.It was traditionally interpreted as a terrigenous shale bed related to a paleo-weathering surface,suggesting a regression event after the Maokouan Stage.Methods:We carried out an investigation in detail for Wangpo Shale and collected the rock and fossil samples.the analysis of X ray diffraction (XRD),paleontology,petrography and lithology are carried out.Results:X ray diffraction (XRD) analysis shows that the Wangpo Shale consists predominantly of montmorillonite (71％),heulandite (23％),and quartz (6％),suggesting an origin from volcanic glass.Petrographic analysis shows that the Wangpo Shale is primarily composed of altered minerals montmorillonite and heulandite with residual tuffaceous structures and vitric pyroclast.Abundant brachiopod fossils occur in the Wangpo Shale,suggesting deposition in a marine environment.Conclusions:These data indicate that the Wangpo Shale is a typical bentonite,derived from volcanic ash fall that was subsequently altered in a marine environment.Sudden ash fall may have destabilized the shallow marine ecosystems at the Guadalupian—Lopingian Boundary,resulting in an ecological crisis for Permian brachiopods.关键词
王坡页岩/斑脱岩/乐平统/陕西梁山Key words
Wangpo shale/bentonites/Lopingian/Liangshan, Shaanxi引用本文复制引用
郭俊锋,宋祖晨,肖良,李相传,郑亚娟,姚肖永,周雪柔..陕西汉中梁山二叠系乐平统底部吴家坪组王坡页岩新认识[J].地质论评,2017,63(5):1169-1179,11.基金项目
本文为国家自然科学基金资助项目(编号:41472015)、中国国家留学基金管理委员会资助项目(编号:201306565037)和中央高校基本科研业务费专项基金资助项目(编号:2013G3274021,2014G3272013)的成果.This paper is funded by the National Natural Science Foundation of China (No.41472015),China Scholarship Council(No.201306565037) and the Special Fund for Basic Scientific Research of Central Colleges,Chang'an University,China (No.2013G3274021,2014G3272013). （编号:41472015）
