新疆阿克苏—巴楚地区寒武—奥陶纪海平面变化与旋回层序的形成  

Sea Level Changes and Formation of Cyclic-Sequence of Cambrian-Ordovician in Akesu-Bachu Area,Xinjiang

作　　者：陈国俊[1,2,3] 薛莲花[1,2,3] 王琪 康剑[1,2,3] 肖立新 史基安[1,2,3] 

机构地区：[1]中国科学院兰州地质研究所 [2]中国石油学会 [3]新疆石油管理局地调处地球物理研究所

出　　处：《沉积学报》1999年第2期192-197,共6页Acta Sedimentologica Sinica

基　　金："九五"国家重点攻关项目

摘　　要：通过研究新疆阿克苏巴楚地区寒武奥陶系沉积特征、层序地层序列及其海平面变化规律，首次识别出２个二级旋回层序、４个三级旋回层序和９个四级旋回层序。重点对三级旋回层序的层序界面性质及其体系域特点进行了深入、细致的分析。研究表明，每一旋回层序的形成，理论上均由海平面相对快速上升、缓慢上升、静止、缓慢下降和快速下降所引起，但实际情况较之复杂。海平面上升的最大幅度发生在丘里塔格晚期—吐木休克早期，之后由于构造运动和全球海平面下降，该区海平面亦快速下降，海水迅速退出本区。The Cambrian Ordovician sequences are the most widespread ones in Tarim basin.More and more results of explorations and exploitations indicate that they are most important source and reservoir rocks in the basin. It is a set of shallow bathyal deposits of carbonate and clastic rocks. The sedimentary facies of the study area were a kind of local platform in Cambrian,and platform open sea shelf in Early Middle Ordovician,at the same period,it was shelf facies in Keping area and open platform facies in Bachu area.In late Ordovician,the bulk areas were rapidly uplifted and changed into land by the influences of Caledonian orogeny. So the Upper Ordovician was hiatus or truncation in most areas of the basin. The variations of sea level had varying scales or orders during the long geological history and it led to formation of various sedimemtary characteristics in which it were objectively recorded in sedimentary rocks and sequences.For this reason,by means of studying the sedimentary features,sequences and boundary characters in the rocks and strata,it is able to estimate the laws of sea level changes during the period of sedimentation,analyse the conditions of paleogeography and paleoclimatology,and provide some scientific basis for exploration of oil and gas.Through study on the deposition characteristics,sequence stratigraphic framework and sea level changes,two second order cyclic sequences,four third-order cyclic sequeces and nine fouth-order cyclic sequences have been recognized.Detailed analysis has focussed on the third-order cyclic sequences. The study shows that the formation of every cyclic sequence is caused by the relatively rapid rise,slowly rise,stagnant,slowly fall and rapid fall of the sea level,in which the maximun sea level rise occured during late Qioulitage period early Tumuxiouke Period and,thereafter,for the sake of tectonic activity and global sea level fall,the sea water withdrawed rapidly from the study area,resulting in the loss of the Upper Ordovician deposition. In brief,acc

关 键 词：旋回层序 体系域 海平面变化 寒武-奥陶纪 地层 

分 类 号：P534.41[天文地球—古生物学与地层学] P731.23[天文地球—地质学]