四川盆地上三叠统划分对比研究

STRATIGRAPHIC DIVISION AND CORRELATION OF UPPER TRIASSIC IN SICHUAN BASIN

四川盆地上三叠统对比长期存在混乱,给盆地整体评价带来困难。通过岩石地层、地震地层、事件地层及高分辨率旋回地层等多种方法讨论了须家河组与香溪群各岩性段的对比关系,得出了全盆地上三叠统的对比关系;指出须四段底可近似看成等时界面;须家河组下部地层自西向东、向南逐层超覆在雷口坡组之上,上部地层在盆地西北部自东南向西北方向剥蚀层位渐次变老。文章建议四川盆地上三叠统废除“香溪群”,统一使用“须家河组”,以利于对全盆地上三叠统进行油气资源整体评价与深化研究。

Correlation of the Upper Triassic in Sichuan basin has long been in confusion, making it difficult to evaluate the basin as a whole. Correlation between the Xujiahe Formation and the Xiangxi Group is performed by using various methods, such as petrostratigraphy, seismic stratigraphy, event stratification and high resolution cyclic stratigraphy, and the Upper Triassic in the whole basin is correlated. The lower boundary of the 4 th member of Xujiahe Fm can be approximately treated as a chronohorizon. The lower strata of Xujiahe Fm override, from west to east and south and layer by layer, the Leikoupo Fm. While in the northwestern part of the basin, the denuded horizons of the upper strata get older from southeast to northwest. It is proposed to abolish the 'Xiangxi Group' and unitarily use the 'Xujiahe Fm' in the Upper Triassic in Sichuan Basin, so as to facilitate the evaluation of oil and gas resources in the Upper Triassic in Sichuan basin as a whole.