【作者】 王弭力； 吴必豪； 田白； 李兴；

【Author】 Wang Mili,Wu Bihao,Tian Bai and Li Xing (Institute of Mineral Deposits,Chinese Academy of Geological Sciences)

【机构】 矿床地质研究所；

【摘要】 马海盆地位于世界罕见的大型内陆盐湖盆地——柴达木盆地北缘中部。盆地的东西部均有光卤石等钾镁盐矿物沉积。笔者经过野外和室内观察研究,确定了23种盐类矿物,并对其共生组合、分布规律及含盐系的地球化学特征作了研究;对钾镁盐的形成条件及方式进行了探讨。更多还原

【Abstract】 Located in the middle of northern Qaidam basin,Mahai subbasin is characterized by continuous deposition of evaporates since late stage of Early Pleistocene.Besides halite,gypsum,anhydrite,glauberite,bissanite and thenardite in the whole subbasin,large quantities of carnallite and bischofite as well as minor amounts of polyhalite,sylvite,langbeinite,kainite and lowewite are accumulated in the enricned carnallite zone in the northeast and the Niulang-Zhinu lake cluster in the west of the subbasin.These potassium-magnesium saline minerals mainly occur at the top of the salt layer or at surface. Potassium and magnesium content and Br·10³/Cl values of the soluble saline minerals vary consistently and tend to increase from bottom to top with several undulations,indicating that the salts in the lake water has been concentrated cyclically.Plasma spectral analysis reveals that the modes of occurrence of Li,Sr and Ba in sediments are related respectively to clay, gypsum and carbonate.δ³⁴ S values are vertically controlled by evaporation fractionation and bacterial action and laterally affected mainly by difference in sulfur sources. The investigation into the evolution of the subbasin and the formation history of potassium-magnesium salts has led us to the conclusion that neotectonism is the most significant factor controlling saline deposition in Mahai subbasin.Neotectonism has resulted in the deposition differentiation in the subbasin,governed the formation of the subsidence center and created conditions for the accumulation of remanent brine and deep recharge water.Remanent brine,leaching water and deep recharge water are three important material sources for Mahai subbasin and serve as substantial basis for the formation of carnallite,bischofite and other potassium and magnesium saline minerals.更多还原