鄂西—渝东晚二叠世长兴期古地理格局及生物礁展布的再认识*

通过地层、古生物、地震相、地震属性分析,笔者发现了利川和石柱地区存在晚二叠世长兴期台内盆地的证据,并分别命名为利川台内盆地和石柱台内盆地。基于上述证据和前人研究成果,对鄂西—渝东地区的古地理格局及生物礁展布提出了新的认识:利川台内盆地、石柱台内盆地及鄂西盆地共同控制了鄂西—渝东地区晚二叠世长兴期台盆相间的古地理格局,生物礁主要沿这3个盆地边缘呈带状展布;鄂西盆地在长兴组一段沉积时期形成,该台地边缘坡度较陡,发育陡坡型生物礁;利川台内盆地和石柱台内盆地分别形成于长兴组一段和组二段沉积时期,其台地边缘坡度较缓,分别发育长一期和长二期缓坡型生物礁。与缓坡型生物礁相比,陡坡型生物礁横向及纵向发育规模更大。

Recognition of palaeogeographical pattern and organic reef distribution in the Late Permian Changhsingian in western Hubei and eastern Chongqing

The stratigraphic,paleontological seismic facies and seismic data illustrated that Lichuan and Shizhu area had syneclises during the Changhsingian of Late Permian which are called Lichuan syneclise and Shizhu syneclise respectively. Based on the above findings and previous research results,the author advanced a new view about the palaeogeographical pattern and reef distribution in the Changhsingian of Late Permian in western Hubei and eastern Chongqing,i.e.,all the Lichuan syneclise,Shizhu syneclise and western Hubei Basin controlled the palaeogeographical pattern with the platform and basin alternatively arranging in western Hubei and eastern Chongqing,and the organic reef had a banding distribution along the above mentioned three platform edges. The western Hubei Basin formed in the depositional period of Member 1 of Changxing Formation,with a steep platform edge which developed the steep slope reef during the Changhsingian. The Lichuan and Shizhu syneclises formed during the depositional period of Member 1 and 2 of Changxing Formation respectively,with gentle platform edges which developed gentle slope reefs in the correspondind period. Compared with the gentle slope organic reefs,the steep slope organic reef shows a larger developing scale on horizontal and vertical.