汉南—川东北灯影组古地理演化:晚震旦世扬子西北缘拉张背景的沉积学证据  

Paleogeographic Evolution of the Dengying Formation in Hannan-Northeastern Sichuan Basin:Sedimentary evidence of the extensional tectonic setting for the northwest margin of the Yangtze Block in the Late Sinian

作　　者：杨瑞青 杨风丽[1,2] 周晓峰 周志 YANG RuiQing;YANG FengLi;ZHOU XiaoFeng;ZHOU Zhi(State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China;School of Ocean and Earth Science,Tongji University,Shanghai 200092,China;Oil&Gas Survey,China Geology Survey,Beijing 100083,China)

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092 [2]同济大学海洋与地球科学学院,上海200092 [3]中国地质调查局油气资源调查中心,北京100083

出　　处：《沉积学报》2019年第1期189-199,共11页Acta Sedimentologica Sinica

基　　金：国家重点研发计划项目(2016YFC0601005);国家科技重大专项(2016ZX05034);中央高校基本科研业务费专项资金(22120180128)~~

摘　　要：古地理面貌的呈现往往是构造演化与沉积充填共同作用的结果。通过对野外露头系统的观察与分析,在汉南—川东北地区进行了晚震旦世灯影期沉积相分析,识别出古隆起、局限台地、开阔台地和台缘斜坡4种类型的古地理单元;确定了汉南—川东北地区地势南高北低、各沉积单元呈南北向和北东向展布,且在平面上呈现"一隆两凹"的古地理面貌特征。在露头及盆地内钻井岩芯识别出的同沉积断层等特征,反映了沉积区处于拉张构造背景;且古地理研究中所确定的沉积坳陷区与隆起区的位置与重磁震等地球物理资料中识别出的裂陷/坳陷和古隆起位置相吻合,证实了四川盆地内绵竹—乐至—隆昌—长宁拉张槽/裂陷槽和万源—达州裂陷槽的存在,表明灯影期汉南—川东北地区处于拉张的构造背景,反映古地理背景发生了由稳定沉积到活动拉张的变化,并且经历了稳定沉积、拉张前奏和主体拉张三个阶段,进一步印证了沉积演化与构造背景之间的耦合关系。The appearance of paleogeography is the result of the joint action of tectonic evolution and sedimentary filling.In this study,which was based on previous research and exploration results,systematic observations and analyses of the field outcrops in Hannan-Northeastern Sichuan Basin were conducted.The results reveal that there are four types of paleogeographic units in Dengying Formation in the Late Sinian:ancient Hannan paleo-uplift,restricted platforms open platforms and slopes.The terrain in the northeastern part of the Hannan-Northeastern Sichuan Basin is lowest in the south and highest in the north;the depositional elements are distributed in the north-south and northeasterly directions.The paleogeographic appearance in the study area was of“one uplift,two depressions”.It is suggested that the study area was in an extensional setting,which is reflected by the characteristics of co-sedimentary faults identified from outcrops and drillings.In addition,the location of the rift/depression identified in the geophysical data is consistent with the location of the ancient land on the paleogeographic map.This confirms the existence of the Mianzhu-Lezhi-Longchang-Changning pull/rift and Wanyuan-Dazhou rift in Sichuan Basin,and also indicates an extensional setting in the study area during the Dengying period.The paleogeographic background was transformed from one of stable deposition to active extension,and experienced stable deposition,prelude and main extension.Thus,this study further indicates the coupling relationship between sedimentary evolution and tectonic setting.

关 键 词：灯影组 古地理演化 拉张背景 汉南—川东北 

分 类 号：P618.13[天文地球—矿床学] P534.31[天文地球—地质学]