青海柴达木盆地北缘全吉群内部存在区域性不整合  

Recognition of the regional unconformity in the Neoproterozoic Quanji Group on the north margin of the Qaidam Basin in Qinghai Province

作　　者：王超[1] 李猛[1] 李荣社[1] 彭岩[2] 张吉衡[3] 张海军[2] 王健[1] 

机构地区：[1]国土资源部岩浆作用成矿与找矿重点实验室/中国地质调查局造山带地质研究中心/中国地质调查局西安地质调查中心,陕西西安710054 [2]中国地质大学地球科学与资源学院,北京100083 [3]中国科学院大学地球科学学院,北京100049

出　　处：《地质通报》2015年第2期364-373,共10页Geological Bulletin of China

基　　金：中国地质调查局项目(编号:1212010610102;1212011121262);中国地质调查局百名青年地质英才计划和陕西省科技计划项目(批准号:2014KJXX-19)

摘　　要：通过野外考察和前人资料分析发现,柴达木盆地北缘全吉群红藻山组之上存在一个区域性的不整合,其中发育铁质风化壳、沉积间断、地层的缺失、侵蚀作用特征。不整合面上、下地层存在古生物组合、沉积环境的突变。界面以下为碳酸盐台地沉积,界面之上代表了冰水沉积到海相潮上—潮间带沉积,上覆黑土坡组—红铁沟组—皱节山组,依次沿着不整合面向上超覆,反映了不整合发育之后的又一次海进过程。该不整合界面可能代表了新元古代晚期该地区裂谷盆地的伸展阶段的构造响应。该区域性不整合的发现,改变了以往传统的对全吉群内部整合关系的认识,说明全吉群需要解体。该不整合可能发生于成冰纪—埃迪卡拉纪。该时期的不整合面上、下生物面貌和沉积环境的变化或突变,可能与新元古代晚期罗迪尼亚超大陆的裂解和全球雪球事件相关。Based on field work in this study in combination with previous researches, the authors recognized a regional unconformity within the Quanji Group. This unconformity overlies the Hongzaoshan Formation. It is featured by the iron palaeo-weathering crust, interruption of sedimentation and erosion of the surface over and below the unconformity. There also exist remarkable differ-ences of paleontological associations and depositional environment on both sides of the unconformity. The Hongzaoshan Formation beneath the unconformity represents carbonate platform sedimentary facies. The Heitupo, Hongtiegou and Zhoujieshan formations and Xiaogaolu Group overlying the unconformity show the sedimentary environments characterized by transform from glaciofluvial deposit to supralittoral-intertidal zone, suggesting a transgression process after the formation of the unconformity. This unconformity may be related to the extension tectonic activity of the late Neoproterozoic rift setting on the northern margin of the Qaidam Basin.＆nbsp;This interpretation indicates that the contact relation between the Hongzaoshan Formation and the Heitupo Formation of the Quanji Group is not a conformable contact as previously believed. This unconformity formed in Cryogenian-Ediacaran period. The differ-ences of paleontological associations and depositional environment on both sides of the unconformity may be related to the breakup of Rodinia supercontinent and snowball Earth deglaciation.

关 键 词：全吉群 新元古代 冰碛岩 不整合 青海省 

分 类 号：P534.3[天文地球—古生物学与地层学] P547.34[天文地球—地质学]