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Objective Yishu fault zone geothermal field and central Shandong uplift geothermal field are typical geothermal fields in south central Shandong Province. In order to investigated the distribution characteristics and mechanisms of fluorine enrichment in the geothermal water of the this area, Methods hydrochemical diagrams, geochemical simulations and principal component analysis were employed. Results The results show that the geothermal water in the study area is mainly Na-Ca-Cl-, Na-Ca-SO4-Cl- and Na-Cl-SO4-type water, dominated by weakly alkaline water. The predominant cation is the sodium ion, with fluorine concentration between 0.38 and 4.5 mg/L. Sodium-rich and weakly alkaline environments are faciliated to the enrichment of fluorine in the geothermal water. The fluorine concentration has significant positive correlations with the Na+, Cl- and TDS concentrations in the geothermal water. In addition, it has significant positive correlations with K+ and SO42- concentrations and significant negative correlations with Mg2+ and HCO3- concentrations in the geothermal water in the Yishu fault zone. The cation exchange effect in the geothermal water of the central Shandong uplift zone is stronger than that in the Yishu fault zone, and the reaction strength of Na+ is significantly stronger than that of Mg2+. The geothermal field of the central Shandong uplift and Yishu fault zones are both fracturing types. The thermal storage lithologies are limestone, limestone in the thermal alteration zone and ansanite in the broken belt, with strong water-rock interactions. The provenance of fluorine in the geothermal water is the dissolution reprecipitation of fluorine-containing minerals, and the fluorine concentration in the geothermal water is further increased by cation exchange and other water-rock interactions. High temperature and sodium-rich have a great influence on fluorine enrichment. Conclusion This research provides a reference for the exploitation and utilization of geothermal resources.

To further explore the diagenetic environment, uranium precipitation mechanism and mineralization mechanism of the sandstone type uranium deposit in Sifangtai Formation on the southern margin of Daqing placanticline in Songliao Basin, the systematic research has been by drilling core observation, rock slice, sandstone uranium containing carbonate cement carbon and oxygen isotopic analysis of the sandstone rock types in the study area, the types of carbonate cements, diagenetic stage and systemic research on the carbon and oxygen isotopic been characteristics, The results show that the uraniferous sandstone rock types are feldspar lithic sandstone and lithic feldspar sandstone, carbonate cement being divided into three periods.For the first time and second time, the priority is given to cement, including calcite, ferroan calcite, see very small amounts of iron dolomite.The value of δ13CPDB is -22.45‰--13.65‰, with an average value of -18.00‰.The value of δ18OPDB is -17.56‰--9.46‰, with an average value of -13.52‰, revealing that there are some organic matters involved.The paleosalinity Z value is between 75.98 and 90.97, which is fresh water deposit.The paleotemperature is between 67.31℃ and 94.92℃, and the diagenetic environment is judged to be in the stage A of early-middle diagenesis based on the above rock features, cementite types and diagenesis.The comprehensive analysis shows that the compaction and cementation of the sadnstone during the early diagenesis stage reduce the porosity of the uranium-bearing sandstone and inhibits the migration of oxygen-rich uranium-bearing fluid.As diagenesis and bruial depth increase, higher organic matter maturity in the hot decarboxylate effect, and the compaction of adsorbed water to form acid solution were formed by dissolution of the feldspar, carbonate cement secondary pore, in order to increase sandstone porosity and promote oxygen rich fluid infiltration of uranium migration.Underlying oil and gas with upward dissipation through fracture provide stratum with reducing agent, making uranium be precipitated and enriched large scale at the bottom of Sifangtai Formation.