PETROGRAPHY,SEDIMENTOLOGY AND RESERVOIR CHARACTERISTICS OF THE CAMBRIAN STRATA IN THE EASTERN YANGZI GORGES AREA

This paper deals with petrography, sedimentology and reservoir characteristics of the Cambrian strata in the Yangzi Gorges area. The genesis and diagenesis of the main carbonate rocks in this region are discussed with the aid of cathodoluminescence, oxygen and carbon isotopes, trace elements X-ray diffraction and electron microprobe analysis. The sedimentary environments are believed to be a shallow-marine carbonate platform controlled by the Huangling-Mianyang continental nucleus, including supratidal zone, intertidal zone, subtidal (low-and high-energy) zone, shallow-marine shelf, slope or ramp and basin or interplatform basin. The finely-crystalline dolostones, algal dolostones, grainstones and reef limestones are main reservoir rocks, and black shales in the Shuijingtuo Formation are the best source rocks in the study area.