Discussion on Genesis of the Upper Triassic Xujiahe Formation Water in
The combination of ions of formation water from the Members 2 and 4 of the Upper Triassic Xujiahe Formation in Xinchang area, Western Sichuan depression, show the characteristics of water from marine strata, especially in the Cl- -Na+ -Br- system, the water also show the mixture by bromine-rich compacting fluids from the adjacent shale and coal beds, and the enrichment of bromine can be used as a symbol of ballast water discharged, the modern formation water have been resulted from mixture of bromine-rich compacting fluids and water of marine. The diagenetic reaction assumption that is proposed for the variation above is in line with previous researches about the diagenesis. More open water-rock reaction system results in formation water of the Members 2 of the Xujiahe Formation being riched in Ca2+, Mg2+, Fe2+, but poor in K+ compared to that of the Members 4 of the Xujiahe Formation water, by which both formation water can be distinguished from each other.