塔里木克拉通寒武系年代框架、层序地层与沉积演化

CAMBRIAN CHRONOSTRATIGRAPHY,SEQUENCE STRATIGRAPHY,AND SEDIMENTARY EVOLUTION OF THE TARIM CRATON

塔里木克拉通寒武系发育良好的源、储、盖层,具有良好的勘探前景,是近年来油气风险勘探的重点领域之一。阐明年代框架,搞清楚地层层序及沉积演化规律,是开展油气勘探的重要基础工作之一。本文通过钻孔测井曲线对比、岩屑碳氧同位素分析及地震层序解释方法,对塔里木克拉通寒武系开展了年代地层、层序地层及沉积演化研究,取得以下3方面成果:(1)通过钻孔岩性、电性对比理清了塔里木盆地内部各相区岩石地层对比关系,在生物地层框架约束下通过同位素地层方法,厘定了塔西台地区与塔东盆地区各岩石地层单位的年代框架。(2)在年代地层框架下,建立了不同相区等时相变关系,并通过地震反射结构特征,将塔里木盆地寒武系划分为4个复合层序、10个层序,建立了各层序沉积空间堆垛模型。(3)提出寒武系经历缓坡碳酸盐岩台地沉积体系—滩边碳酸盐岩台地沉积体系—礁边碳酸盐岩台地沉积体系—无障壁碳酸盐岩台地沉积体系的演化过程,建立了各层序的沉积模式,恢复了沉积演化规律,以层序为单元编制了沉积相图。

The Cambrian system in the Tarim Craton has well-developed source,reservoir and cap rocks,and has good exploration prospects.It has been one of the key areas of oil and gas risk exploration in recent years.We studied the chronostratigraphy,sequence stratigraphy,and sedimentary evolution of the Cambrian in the Tarim Craton by comparing borehole logging curves,analyzing carbon and oxygen isotopes in rock debris,and interpreting seismic sequences.The following three First,the lithostratigraphic correlation of various facies areas was clarified through the comparison of borehole lithology and electricity,and the chronostratigraphy framework was elucidated through carbon isotope stratigraphic correlation under the constraint of the key biostratigraphy maker.Secondly,under the framework of chronostratigraphy,the isochronous facies transformation relationship among different facies regions was revealed.Based on the seismic reflection structure characteristics,the Cambrian sequence stratigraphy framework in Tarim Craton could be divided into four composite sequences and 10 sequences,and the sedimentary space stacking model of each sequence was established as well.Thirdly,we proposed that the sedimentary evolution of the Cambrian experienced an evolutionary process from slope carbonate platform to margin carbonate platform and to reef margin carbonate platform.The sedimentary model of each sequence was generated,and the sedimentary evolution was reconstructed,and the sedimentary facies map was compiled for major sequence units.