扬子地块北缘晚二叠世长兴期岩相古地理

摘要

扬子地块北缘与秦岭接壤,晚二叠世长兴期岩石地层单元为长兴组和大隆组.长兴组为一套碳酸盐岩沉积.沉积单元包括台地相、台地边缘礁滩相以及台地边缘斜坡相等；而大隆组则主要为一套灰黑至黑色薄层硅质岩、炭质页岩夹薄层泥晶灰岩,为一套较深水盆地沉积的产物.研究结果表明,这一深水盆地环境大致从西边的广元开始,向东经旺苍、南江与鄂西地区相连成为一广阔海域,扬子地块与华北地块隔海相望.这一沉积格局不仅为油气勘探工作的部署奠定了坚实的基础,而且可能反映出扬子地块与华北地块在此之前已经成为统一陆块.%The northern margin of Yangtze Block borders on Qinling orogen. In Changxing Phase, its rock-stratigraphic unit includes Changxing Formation and Dalong Formatioa Changxing Formation is composed of carbonate sediment and its main sedimentary facies include platform fades, platform edge reef and bank fades, and platform edge's slope facies. But Dalong Formation is mainly composed of a suite of gray/ black thin bedded silica rock, bass and a little interbed of cryptite. All these are deposited in somewhat deeper basin. The research result shows that the range of deeper basin is from west to east, L e. , from the western Guangyuan to Wangchang to Nanjiang to the western Hubei province. And the deeper basin separated the Yangtze Block from the North China Block. This kind of pattern implies the direction of exploration and may indicate that the Yangtze Block and the North China Block have already joined as a whole land block before the Changxing Phase.