现代地质2018，Vol.32Issue(1)：77-85,9.DOI:10.19657/j.geoscience.1000-8527.2018.01.07
云南思茅盆地上白垩统勐野井组自形黄铁矿成因及地质意义
Genesis of Euhedral Pyrites in the Upper Cretaceous Mengyejing Formation in Simao Basin, Yunnan and Its Geological Significance
摘要
Abstract
The Simao Basin is located in the southeastern part of the Tethyan metallogenic belt.The Mengyejing Formation containing evaporite successions in the Upper Cretaceous is widely distributed in this region.The Mengyejing Formation is currently the only pre-Quaternary solid potash deposit in China.Samples of gypsum and pyrite were collected from the Mengyejing Formation in Jiangcheng County in Simao Basin,and the analysis of major and trace elements and sulfur isotopes of these samples were performed by electron probe micro-analyzer (EPMA) and mass spectrometer.The results show that the S/Fe value of pyrite is 2.02,showing that it belongs to a sulfur-concentration type pyrite.The Co/Ni values range from 3.01 to 10.74,and the varying range is larger.The δ34Sv-cDrvalues of pyrite are in the range of-8.36‰ to-3.36‰ with an average of-6.33‰c,while the δ34Sv.cDT values of gypsum are in the range of 6.6‰ to 10.7‰ with an average of 9.48‰.The values of S/Fe,Co/Ni and sulfur isotope of pyrites and the values of sulfur isotope of gypsums suggest that the pyrite in the Mengyejing Formation in Jiangcheng County is formed in hydrothermal processes.The hydrothermal alteration causes the gypsum to be reduced to form S2-.S2-formed the granulated pyrite combined with Fe from the hydrothermal fluid.Through this study of the genetic mechanism of pyrite and gypsum of the Mengyejing Formation,it comes to the conclusion that the primary evaporites of the Mengyejing Formation in the Upper Cretaceous might be experienced obvious alterations by deep hydrothermal fluids accompanied by several kinds of metals,which is controlled by the Indian and Asian collision,and the hydrothermal activities in Simao Basin recrystallized the potash minerals of the Mengyejing Formation,but might have favorable contribution to the metal deposition.关键词
勐野井组/思茅盆地/黄铁矿/石膏/成因/硫同位素Key words
Mengyejing Formation/Simao Basin/pyrite/gypsum/genesis/sulfur isotope分类
天文与地球科学引用本文复制引用
董浩伟,王立成,刘成林,魏玉帅,王延路,伯英..云南思茅盆地上白垩统勐野井组自形黄铁矿成因及地质意义[J].现代地质,2018,32(1):77-85,9.基金项目
国家自然科学基金项目“云南兰坪—思茅盆地白垩纪中期海侵事件及其与钾盐成矿的关系研究”(41572067) （41572067）
国家自然科学基金项目“兰坪—思茅盆地勐野井矿区地表钾异常形成的深穿透机理研究”(41502080). （41502080）
