Geochemical characteristics of gypsum and its geological significance in Jinding Mining area of Lanping basin, western Yunnan

In order to understand the relationship between gypsum and metallogenic in Jinding mining area of Lanping basin, the rare earth, trace elements, strontium and sulfur isotopes of gypsum have been studied. The results show that strontium isotope of gyrpsum (⁸⁷Sr/⁸⁶Sr = 0.707695 ∼ 0.707988, averaging 0.707817) is close to strontium isotope in the limestone samples of Sanhedong formation in Late Triassic (⁸⁷Sr/⁸⁶Sr = 0.707795 ∼ 0.708313, averaging O.707984). Sulfur isotope δ³⁴S_v.CDT of gypsum is mainly concentrated in 12.6% ∼ 17.99%, averaging + 15.05‰, close to δ³⁴S (+ 15‰) of Late Triassic Paleo oceanic sulfate, combined with the geochemical characteristics of rape earth elements and the distribution patterns of REE, the results show that the thick-massive layer of gypsum is evaporation and deposition plaster of Sanhedong formation in Late Triassic. The REE geochemistry parameters of gypsum in Jinding mining area compare with single mineral fluid inclusion of different mineralization stages, and geochemical analysis of trace elements, the results show that the relationship between gypsum of Sanhedong formation in Late Triassic and metal sulfide mineralization is closely. (authors)