The Origin of the Upper Cambrian Basin-Scale Massive Dolostones of the Xixiangchi Formation, Sichuan Basin, China

The thick Upper Cambrian Xixiangchi dolostones, developed in the Sichuan Basin, are an important deep exploration target, but their genesis is still controversial, which hinders predicting porous dolomite distribution and related potential hydrocarbon play. Herein, based on observation sampling of field outcrops, combined with a microscopic thin section analysis, cathodoluminescence geochemical study, characteristics were investigated. results showed that there mainly three types can be distinguished: (1) fine crystalline low crystallinity (Type 1); (2) granular coarse grains, maintaining original particle structure 2); (3) grain-texture relict higher degree crystal form obvious recrystallization 3). Type 1 common lamina highest 87Sr/86Sr ratio implies most continental-influenced seawater supratidal environment around paleouplift, where evaporation pump effect its formation. 2 recorded slightly diagenesis temperature lower brine salinity, would formed seepage-reflux model beach platform. lowest REY content structural residuals indicate 3 result further burial dolomitization during diagenetic process.