| The discovery in the Wusonggeer Formation as a potential new layer for risk exploration in the Cambrian
subsalt dolomite field is a significant breakthrough in Tarim Basin. Understanding the genesis and evolution of dolomite
is crucial for the formation, preservation, and evaluation of high-quality carbonate reservoirs. This study focus on the
outcrops of Wusonggeer Formation in the Keping area. By analyzing the geochemical characteristics including trace
element content, rare earth element content, and carbon and oxygen isotopes composition of the Wusonggeer
Formation’s dolomite, origin of dolomitization and source of dolomitized fluids in the study area were discussed, and
possible dolomite patterns were explored. It is shown that the dolomites in the study area have formed in a sedimentary
environment characterized by arid and hot climates, saline seawater, and oxidation. The relatively low ΣREE value (5.51-
89.10 μg/g, with an average value of 27.32 μg/g）and obvious low negative value of δ13C (from -3.14‰ to -0.73‰ ) , and
the high negative value of δ18O (from -10.45‰ to -6.19‰ ) indicates that the diagenesis process was significantly
affected by the leaching of atmospheric fresh water. The 87Sr/86Sr value and REE distribution patterns of the dolomite are
similar to those of dolomite originating from seawater, and the salinity index (Z) of the dolomite is higher than that of
normal seawater. Therefore, it is inferred that the dolomite fluid mainly comes from high salinity seawater. This study
provides important insights into the formation mechanism of dolomite reservoirs and the prediction of high-quality
reservoirs in the study area. |
