大柴旦盐湖硼矿床与国内外硼矿床的对比研究

The Study on Borate Deposit of Da Qaidam Salt Lake Compared to Other Borate Deposits in the World

大柴旦盐湖因蕴藏固体和液体硼矿资源成为柴达木盆地诸多盐湖中最早被关注和开发的盐湖之一;不仅如此,还沉积有全球少有分布的湖底特色柱硼镁石矿床。基于大柴旦盐湖硼矿床的地质特征和硼同位素地球化学特征,与国内外不同硼矿床开展对比研究,旨在探讨主控硼矿床形成的影响因素及其异同点。研究发现,大柴旦盐湖硼矿床与国内外硼矿床的形成均受控于新构造运动、封闭—半封闭的低洼汇水盆地以及极度干旱的气候条件等因素,所有硼矿床均与火山岩或含电气石花岗岩有密切关联,成矿物质特别是硼元素主要来源于火山岩或含电气石花岗岩,经热泉水、温泉水和大气降水的水岩作用后迁移富集。主控因子化学组分或盐湖水化学特性的不同致使硼矿物的种类和矿物共生组合特征等方面表现出一定的差异性。

Da Qaidam Salt Lake,northern Qaidam Basin,is known for its liquid and solid boron resource.More than that,pinnoite bearing sediments,occurred in this lake,are rare in the world. Based on the geological characteristics and boron isotopic geochemical characteristics of Da Qaidam Salt Lake,and compared to other borate deposits in the world,the study aims to discuss the controlling factors of borate formation and differences. The results showed that all borate deposits controlled by neotectonics,enclosedsemienclosed low catchment basin and hyper-arid climate conditions,as well as volcanics or tourmaline granite,the metallogenic materials especially boron are derived from volcanics or tourmaline granite,which migrated and enriched after water-rock interaction by thermal spring water and atmospheric precipitation.Chemical composition or salt-lake hydrochemical characteristic is a main controlling factor,which resulted in the differences of borate ore and mineral assemblages.