雪峰山地区震旦系-寒武系之交黑色岩系地球化学特征:物源、气候与构造背景  

Geochemical Characteristics of Black Rock Series in the Transition Zone Between Sinian and Cambrian Systems in the Xuefengshan Area:Implications for Their Provenances,Paleoclimate and Tectonic Setting

作　　者：张国涛[1] 陈孝红[1] 王保忠[1] 张保民[1] 陈林 ZHANG Guo-tao;CHEN Xiao-hong;WANG Bao-zhong;ZHANG Bao-min;CHEN Lin(Wuhan Center of China Geological Survey,Wuhan 430205,China)

机构地区：[1]中国地质调查局武汉地质调查中心,武汉430205

出　　处：《矿物岩石地球化学通报》2022年第2期414-428,共15页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：中国地质调查局地质调查项目(DD20190109,12120114053801)。

摘　　要：新元古代末至早寒武世是地球历史上最重要的时期之一,雪峰山地区刀背溪剖面发育该时期连续完整地层,为探讨该区黑色岩系的发育控制因素,对该剖面下震旦统金家洞组、上震旦统留茶坡组、下寒武统牛蹄塘组3套连续黑色岩系进行了元素地球化学分析,探讨了沉积盆地的构造背景、物源及古气候变迁。结果显示,金家洞组和牛蹄塘组物源为长英质火山岩,而留茶坡组物源为偏铁镁质物源,金家洞组与牛蹄塘组源区的构造背景都具有大陆弧特征,而留茶坡组则具有大洋岛弧特征。基于构造事件与ICV、CIA、δEu等指标分析发现,3组黑色岩系源岩本质上均来自华夏与扬子板块碰撞形成的陆缘弧,但华南裂谷盆地作为Rodinia超大陆解体过程中的重要组成部分,在震旦纪-寒武纪之交经历了从板内持续伸展至稳定的构造演化全过程,尤其是留茶坡组沉积期拉伸作用达最大,导致大陆岛弧环境演化成类大洋岛弧环境。马里诺冰期后,震旦纪气候开始转暖,整体上温暖潮湿但不稳定,仍有短暂的寒冷气候,至早寒武世气温进一步升高,稳定温湿的气候为全球生命大爆发提供了必要条件。3个层系均发育黑色岩系,但控制因素不同,下震旦统黑色岩系的发育主要受板内伸展活动控制,晚震旦世区域性升降运动可能对上震旦统黑色岩系的发育起到了更为关键的作用,至早寒武世气候导致的海平面变化是下寒武统黑色岩系发育的主要控制因素。The Late Neoproterozoic to Early Cambrian is one of the most important periods in the history of Earth evolution.The continuous and complete strata of this period were developed in the Daobeixi section in the Xuefengshan area.In this paper,in order to discuss controlling factors for the development of black rock series in the Xuefengshan area,we have carried out geochemical analysis of three sets of continuously developed black rock series in the Sinian System and Lower Cambrian Series,and then have studied the tectonic setting,material source and paleoclimate change of the sedimentary basin.The results show that provenances of the Lower Sinian Jinjiadong Formation and the Lower Cambrian Niutitang Formation are felsic volcanic rocks with characteristics of those formed in the continental arc setting,while provenance of the Upper Sinian Liuchapo Formation is mafic volcanic rocks with characteristics of those formed in the oceanic island arc setting..Based on studies on tectonic events,and the ICV,CIA,δEu and other indicators of those black rocks,it is found that three sets of black rock series are essentially sourced from the continental marginal arc formed due to the collision of the Cathaysian and the Yangtze plates.As an important part of the disintegration of Rodinia supercontinent,the South China rift basin experienced the whole process of tectonic evolution from the intraplate continuous extension to the plate stability at the turn from Sinian to Cambrian periods.In particular,the maximum extensional activity had reached in the sedimentary process of the Liuchapo Formation in the late Sinian,resulting in the transformation of the continental marginal arc environment into an oceanic island arc-like environment.After the Marino Glaciation,the climate of the area in the Sinian Period generally began to warm and humid,but cold in some short times,and then the climate temperature was further increased in the Early Cambrian.The stable warm and humid climate provided the necessary condition for the global life out

关 键 词：雪峰山隆起 震旦系 寒武系 黑色岩系 物源 构造背景 古气候 

分 类 号：P581[天文地球—岩石学]