四川乐山震旦系灯影组火山碎屑岩锆石LA-ICP-MSU-Pb定年及盆地裂陷演化讨论

发布时间：2018-03-27 19:30

本文选题：四川盆地　切入点：寒武纪　出处：《地质论评》2017年04期

【摘要】：四川盆地中部晚震旦(埃迪卡拉)世—早寒武世克拉通内裂陷与安岳震旦(埃迪卡拉)系—寒武系特大气田的形成关系密切,年代学研究对认识克拉通内裂陷构造意义重大。对四川盆地乐山先锋剖面灯影组三段火山碎屑岩进行锆石LA-ICP-MS U-Pb定年,研究结果表明四川盆地灯影组三段火山碎屑岩的锆石U-Pb年龄为(539.6±1.4)Ma,年代学结果表明四川盆地灯三段与灯四段属于寒武系。基于灯影组底界(551.1 Ma)、含火山碎屑岩的灯三段(539.6 Ma)、含小壳化石的麦地坪组(535.2 Ma)和下寒武统Ni—Mo多金属硫化物富集层(521.0 Ma)四个等时面构建了克拉通内裂陷演化的时间框架。在此基础上认为四川盆地中部晚震旦(埃迪卡拉)世—早寒武世隆坳构造的形成主要受边界断裂控制,断层活动使裂陷内水体加深,少量灯四段含硅质白云岩沉积后,麦地坪组与筇竹寺组开始沉积,麦地坪组与灯四段的界线在裂陷内与裂陷两侧并不等时,裂陷内麦地坪组、筇竹寺组与裂陷两侧灯影组四段为同期异相沉积。
[Abstract]:The late Sinian (Eddie Carla) -early Cambrian craton rift in the central Sichuan Basin is closely related to the formation of the Anyue Sinian (Eddie Cara) -Cambrian giant gas field. The chronological study is of great significance to the understanding of the tectonic structure of the craton inner rift. Zircon LA-ICP-MS U-Pb dating of volcanic clastic rocks of the third member of the Dengying formation in the Leshan Pioneer profile, Sichuan Basin, is carried out. The results show that the zircon U-Pb age of the third member of the Dengying formation in Sichuan Basin is 539.6 卤1.4 Ma.The geochronological results show that the third and fourth member of the Dengying formation belong to Cambrian. The time frame for the evolution of the craton inner rift was constructed on the four isochron of the Madiping formation containing small crust fossils and the Ni-Mo polymetallic sulphide enrichment layer of the Lower Cambrian (521.0 Ma). Based on this, it is considered that the late Sinian in the central Sichuan Basin. The formation of the Edikala (early Cambrian) uplift depression was mainly controlled by the boundary faults. The fault activity deepens the water body in the rift. After a small amount of siliceous dolomite deposits in the fourth member, the Madiping formation and Qiongzhusi formation begin to deposit. When the boundary between the Madiping formation and the fourth member of the mai Diping formation is not the same as the two sides of the rift depression, the inner mai diping formation in the rifting is not equal to the two sides of the rift. The fourth member of Qiongzhusi formation and Dengying formation on both sides of the rift are synchronal and heterogeneous deposits.
【作者单位】：南京大学内生金属矿床成矿机制研究国家重点实验室;中国石油勘探开发研究院廊坊分院;首都师范大学;
【基金】：国家科技重大专项(编号:2016ZX05003-001、2017ZX05008-001) 国家自然科学基金资助项目(编号:41230208)的成果~~
【分类号】：P597.3;P618.13

【相似文献】