四川盆地灯影组与雷口坡组层序沉积特征对比研究

The characteristic comparing study of sequence and sedimentation in the Sichuan basin Dengying fomation and Leikoupo formation

作为四川盆地海相碳酸盐岩沉积的始末两个阶段,本文选取震旦系灯影组和中三叠世雷口坡组这两个特殊时期进行比较研究,来窥探盆地内整个海相沉积的发展过程。通过选取典型的剖面和井资料,结合层序地层学的原理和方法,对层序格架、沉积演化模式等方面做了整理和总结,认识到始末两个时期在层序格架上相似,都具有快速海侵,缓慢海退的海平面变化特征。在灯影组时期四川盆地总体表现为西高东低,这一长期稳定的格局在雷口坡组沉积时期由于江南古陆隆起变为东高西低,物源供应方向也从沉积开始的由西向东变为由东向西搬运。灯影组造礁生物为单一的藻类,由于生物灭绝事件和气候条件,雷口坡组的造礁生物也几乎只发育单一的藻类。

As the beginning and the end of marine carbonate sedimentary in Sichuan basin,in order to scan the whole marine sedimentary development process,this article selects the Sinian Dengying formation and the middle Triassic Leikoupo formation as the two special period to compare and study.Through selecting typical profiles and well data,combined with the principle and method of sequence stratigraphy,collecting and summarizing the sequence framework,sedimentary evolution pattern and so on,realize that the two period are similar in sequence stratigraphic framework which have the same sea level changes of rapid transgres- sive and slow regressive.The Sichuan basin is high in the west and low in the east in the whole period of Dengying formation.But this long-term stable patterm have changed into high in the east and low in the west during the Leikoupo formation sedimentary period because of the rise of Jiangnan ancient land.Source supply direction also changed from west to east in the beginning to east to west.The reef-building organisms in the Dengying fomation only have algae.Due to the extinction events and climate conditions,the reef-building organisms in the Leikoupo formation are almost single algae.