基于水文地球化学模拟的昆特依盐湖杂卤石成矿流体来源初步研究

Preliminary Study on the Source of formation-ore fluids of Polyhalite in Kunty Playa Based on Hydrogeochemical Simulation

柴达木盆地昆特依盐湖赋存大量杂卤石。研究结果显示,苏干湖湖水模拟蒸发析出的盐类矿物与研究区实际情况相符,但杂卤石析出量很少;油田卤水模拟析盐结果中没有发现杂卤石,且析出盐类矿物与实际情况差异很大。典型钻孔杂卤石饱和指数(SI)分析表明,卤水相对杂卤石而言是不饱和的。综合分析揭示,地表水应该是昆特依盐湖成盐物质的主要来源,而深部油田卤水对于杂卤石的形成具有重要作用,杂卤石的沉积是不同流体混合作用的结果。

There are voluminous polyhalite deposits in Kunty Playa of north Qaidam Basin.The present study shows that the saline minerals formed by evaporation simulation of Suganhu lake water is in accordance with the facts in the area,while only little polyhalite is found during the process.For oilfield waters,no polyhalite is found during the simulated evaporating process and the saline minerals from the simulation are obviously different with the fact.The analyses result of saturation index(SI) from typical core profile shows that these brines are undersaturated relative to polyhalite.Comprehensive analyses suggest that surface water should be main source of Kunty playa and the oilfield brines play an important role in the formation of polyhalite.The deposition of polyhalite is the result of mixing of different fluids.