中国科学院南京地质古生物研究所机构知识库

蒸发岩是保存古环境信息的宝库,而石盐是蒸发岩盆地完全干涸后最主要的矿物。石盐矿物具有很好的封闭性,在浅埋深状态就会固结成岩,没有孔隙并且不可压缩。石盐、石膏、钙芒硝、芒硝中的包裹体,是潟湖或陆地盐湖环境下,通过蒸发而结晶析出过程中所捕获的流体（液体和/或气体）。因此,在石盐矿物的内部可以保存下来良好的原生石盐流体包裹体,它们记录了原始海洋/盐湖的温度、化学组分和大气成分的信息,为古环境研究提供了绝妙的直接记录。其中石盐原生流体包裹体的均一温度,可记录卤水沉积时的温度;浅水环境石盐流体包裹体记录的卤水温度近似等于气温。石盐原生流体包裹体中的卤水成分代表了海水/盐湖蒸发浓缩过程中的卤水,可通过其来推断当时的海水/盐湖水体的成分。石盐漏斗晶形成时是漂浮在卤水表面的,其原生流体包裹体可捕获当时的大气,而石盐是一种稳定的无机矿物,其原生流体包裹体可保存原始的大气信息。石盐原生流体包裹体可以提供其他传统地球化学手段无法提供的直接、精确、定量的地质记录,因此在未来的古环境研究中将成为焦点。

Evaporite is a treasure chest for reserving the information of ancient environments. Halite is the most widely distributed evaporitic mineral in the completely dried evaporitic basin. Halite has good closure and will be consolidated to halite rock with poreless and incompressible features in a shallow buried state. Fluid inclusions in halite,gypsum and glauberite,and mirabilite contain fluids（ liquid or/and gases） which were captured during their crystalizations in the evaporation process of ancient marine lagoon or continental salt lake. Therefore,primary fluid inclusions in halite can record informations of temperature,chemical composition of the ocean,salt lake,and composition of the atmosphere in geological times directly,and can provide excellent direct records of paleoenvironments. Homogenization temperatures of primary fluid inclusions in halite can represent the brine temperature during halite crystalization. In shallow brine,the highest homogenization temperatures of fluid inclusions in halite can approximately represent the air temperature. The compositionsof brines in primary fluid inclusions in halite can respectively represent those of seawater/salt lake water during evaporation process,and then can be used to infer the composition of seawater/salt lake water at that time. The halite funnel crystals,which were formed and floated in the top part of the brine,can capture ancient atmosphere as gas bubbles in primary fluid inclusions of the halite,indicating that primary fluid inclusions in halite can preserve original information of the paleo-atmesphere. Therefore,primary fluid inclusions in halite can provide accurate,direct and quantitive geological records that are not available by other traditional geochemical means,and will become the focus of paleoenvironmental studies in the future.