康滇古陆两侧五峰组—龙马溪组沉积演化差异  

Sedimentary Evolution Difference in the Black Mudstone of Wufeng Formation-Longmaxi Formation on both Sides of Kangdian Ancient Land

作　　者：张茜 张海全 王剑 门玉澎 余谦 周业鑫 曹竣锋 赵安坤 ZHANG Qian;ZHANG HaiQuan;WANG Jian;MEN YuPeng;YU Qian;ZHOU YeXin;CAO JunFeng;ZHAO AnKun(Chengdu Center,China Geological Survey(Geosciences Innovation Center of Southwest China),Chengdu 610218,China;Key Laboratory of Sedimentary Basin and Oil&Gas Resources,Ministry of Land and Resources,Chengdu 610218,China;School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China)

机构地区：[1]中国地质调查局成都地质调查中心(西南地质科技创新中心),成都610218 [2]自然资源部沉积盆地与油气资源重点实验室,成都610218 [3]西南石油大学地球科学与技术学院,成都610500

出　　处：《沉积学报》2024年第6期2144-2158,共15页Acta Sedimentologica Sinica

基　　金：贵州省自然科学基金项目(2023-344,2022-ZD005)。

摘　　要：【目的】深入研究康滇古陆东西两侧五峰组—龙马溪组黑色泥岩沉积环境及沉积构造演化差异,旨在支撑区域页岩气勘探开发及相关研究。【方法】通过全面的地质调查及系统矿物岩石学及地球化学分析,综合对比研究了古陆东侧昭通地区及西侧盐源盆地五峰组一龙马溪组黑色泥岩沉积的物源属性、古海洋环境及古气候特征。【结果】东侧陆源碎屑指示参数Al_(2)O_(3)、TiO_(2)、Sc、Zr等元素均较西侧富集,而MoEF、UEF及V/Cr、U/Th等水体氧化还原性指标参数均较西侧低。两侧沉积环境差异明显,东侧属于局限海陆棚沉积,富有机质页岩以硅质钙质岩系为主,而西侧属于开阔海陆棚,富有机质页岩为硅质岩系。东侧距物源更近,源岩以长英质火成岩为主,化学风化作用更强,气候也更温暖,沉积水体较浅,以弱氧化—贫氧环境为主。西侧水体较深,以缺氧还原环境为主,构造运动较强,背景更复杂,有活动大陆边缘及岛弧环境属性,可能与西侧洋壳与扬子陆壳的碰撞相关。【结论】富有机质页岩的形成是不同的沉积构造演化模式下多因素共同作用的结果。相比而言,古陆西侧富有机质页岩的形成主要受控于还原性水体有利的保存条件,而东侧则主要受控于弱氧化环境下生物繁盛造成的极高古生产力。[Objective]This study examined the difference of sedimentary environment and tectonic evolution of the Wufeng Formation-Longmaxi Formation on the east and west sides of the Kangdian ancient land to support regional shale gas exploration and development and related research.[Methods]Based on a comprehensive geological survey and systematic mineralogical,petrological,and geochemical analysis,the provenance,paleoredox environment,and paleoclimate characteristics of black mudstone in the Wufeng Formation-Longmaxi Formation in the Zhaotong area on the east side of the ancient land and Yanyuan Basin on the west side were studied[.Results]The results show that the indicator parameters of terrigenous detrital such as Al_(2)O_(3),TiO_(2),Sc,and Zr on the east side are more enriched than those on the west side,whereas the redox index parameters of MoEF,UEF,V/Cr,and U/Th are lower than those on the west side.There are clear differences in the sedimentary environment between the two sides.The eastern side is confined to marine shelf deposits,and the organic-rich shale is dominated by siliceous calcareous rocks.The west side is an open marine shelf,and the organic-rich shale is a siliceous rock series.Well XD2 on the east side is closer to the ancient land,the parent rock is mainly felsic igneous rock,the chemical weathering is stronger,the climate is warmer,and the sedimentary water is shallow and dominated by weak oxidation environment.The western side of the water body is relatively deep and dominated by anoxic reduction,with strong tectonic movement and more complex tectonic background,as well as active continental margin and island arc environmental properties,which may be related to the collision between the western ocean crust and Yangtze continental crust.[Conclusions]The formation of organic rich shale is the result of multiple factors together under different sedimentary evolution patterns.In comparison,the formation of organic rich shale on the western side of the ancient land is controlled by favorable preservatio

关 键 词：康滇古陆 五峰组—龙马溪组 地球化学 沉积环境 构造背景 

分 类 号：P595[天文地球—地球化学]