Abstract:

The northern margin of Yangtze Block borders on Qinling orogen. In Changxing Phase, its rockstratigraphic unit includes Changxing Formation and Dalong Formation. Changxing Formation is composed of carbonate sediment and its main sedimentary facies include platform facies, platform edge reef and bank facies, 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, i.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.

Key words: north margin of Yangtze Block； Changxing Phase, lithofacies paleography； platform edge reef/bank facies； reservoir