The Origin And Mineralization Significance Of The Paleogene Salt Minerals In Lixian Sub-depression

Lixian sub-depression,as a secondary sub-depression of Jiangling depression in southwest,its formation in paleogene in the development of rock salt and anhydrite,saline minerals such as calcium mirabilite,forming large scale of evaporite deposits.The deposit belongs to the typical terrestrial clastic-chemical rock type salt deposit,and has been exploited for a long time.Has plenty of oil and gas exploration in Jiangling de pression development,the understanding of the basic geological problems such as structure,sedimentary is relatively deep and accumulated a lot of basic data,but the development of the salt resources in the depression of targeted research is less.For is located in the southwest edge of Jiangling depression Lixian sub-depression,the study of the saline minerals are more rare.To fill this gap,this study intends to Jiangling depression through collecting and sorting the south rim regional geological background,aiming at Lixian sub-depression ZK0303 drilling core of core logging,sampling,and draw out the core comprehensive figure.Selecting representative section of the layer of salt mineral samples,thin section identification,X-ray diffraction analysis and sulfur isotope analysis technology,deep research Lixian sub-depression,the characteristics and the causes of saline minerals.The petrology and mineralogical characteristics of ZK0303 core evaporite show that the evaporite is deposited in the perennial salt lake.Drilling evaporite period of native sulfur isotope characteristics of glauberite,showed that the sulfur source Lixian sub-depression,calcium mirabilite has little to do with the sea,under the condition of the sulfur isotopes in the natural biological fractionation is not obvious,sulfur may come from the western Huangling uplift and older evaporite Dabieshan orogenic belt,etc.Based on the available drilling data and previous study found that Lixian sub-depression,potassium mineral mainly occurs at the beginning of the new system and palaeocene of Xingouzui formation in Shashi formation;Lixian northern sub-depression Shenjindu-Donggang sunken into potassium is yet to be identified,the southern Yanjing sunken(including brine mining area)relatively insufficient potassium metallogenic conditions.