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

发布时间：2018-04-28 23:24

本文选题：王坡页岩 + 斑脱岩　；参考：《地质论评》2017年05期

【摘要】：陕西汉中梁山瓜德鲁普统—乐平统界线(GLB)附近的吴家坪组底部王坡页岩段长期以来被认为是古风化壳沉积,代表了茅口期后暴露于地表风化剥蚀的产物。最近对该地层进行了重新研究,采集了系列岩石和化石样品,进行了X射线衍射、古生物学、岩相学和岩石学分析。X射线衍射分析表明该粘土层主要矿物成分为蒙脱石71%,片沸石23%,石英6%,暗示其物质来源于火山玻璃。岩相学分析显示岩石主要由蚀变矿物组成,具有蚀变残留玻屑凝灰质结构,其中蒙脱石、片沸石保留了原岩中的玻屑的塑性形态。粘土层中大量腕足动物化石暗示其为海相环境。研究结果表明王坡页岩是典型的斑脱岩,并非风化壳和长期剥蚀的产物,而是峨眉山大火成岩省火山喷发时火山灰在海相环境下沉积、蚀变的产物。火山灰在正常浅海沉积时对海洋生态系统造成严重破坏,导致了包括腕足动物在内的海洋生物的生存危机。
[Abstract]:The Wangpo shale formation at the bottom of the Wujiaping formation near the Gelupin-Leping boundary line in Liangshan County Shaanxi Province has long been considered as a paleo-weathered crust deposit representing the product of surface weathering and denudation after the Maokou period. The strata have recently been restudied, a series of rock and fossil samples have been collected, X-ray diffraction, paleontology, X-ray diffraction analysis shows that the main mineral components of the clay layer are montmorillonite 71, zeolite 2310, quartz 6, suggesting that the material originates from volcanic glass. The petrographic analysis shows that the rock is mainly composed of altered minerals and has a residual glassy tuff structure in which montmorillonite and schist zeolite retain the plastic morphology of glassy debris in the original rock. A large number of brachiopod fossils in the clay layer indicate that they are marine environments. The results show that Wangpo shale is a typical porphyry, not the product of weathering crust and long-term denudation, but the product of volcanic ash deposition and alteration during volcanic eruption in Emeishan great igneous province. Volcanic ash caused serious damage to marine ecosystem when deposited in normal shallow water, resulting in the survival crisis of marine life, including brachiopods.
【作者单位】：长安大学地球科学与资源学院国土资源部岩浆作用成矿与找矿重点实验室;陕西省早期生命与环境重点实验室(西北大学);中国地质大学长城学院地球科学与资源系;
【基金】：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) 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~~
【分类号】：P534.46

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