地表过程与盐湖学中锂同位素地球化学应用

The application of lithium isotopic geochemistry for salinology and surface environment processes

由于具有较大的相对质量差异,锂同位素在地球化学过程中分馏程度较高。尤其是在地表环境中,锂同位素分馏现象最为明显。本文介绍了锂元素的基本性质,讨论了锂同位素分馏行为以及存在的争议。其次,地表环境中河水或海水锂同位素特征作为构造事件和气候变化的地球化学响应,可反映区域构造、气候条件以及风化程度,并且有可能作为定量计算大陆硅酸盐风化CO_2消耗量的指标。另外,在现阶段盐湖学研究中,锂同位素主要用来示踪盐湖锂的物质来源,同时也应结合其它示踪元素,共同研究锂资源来源以及找矿问题。但能否利用盐湖沉积物或者卤水的锂同位素组成来定量计算硅酸盐化学风化过程CO_2消耗量,为全球碳汇及相关古气候、古环境研究提供依据,还有待做更深入的细致调查与验证。

Lithium isotopes are effective tracers of geochemical processes due to their large relative mass difference and therefore fractionation degree, especially in the surface environment. This study attempts to introduce the basic properties of lithium and discuss the knowledge of lithium isotope fractionation behaviors, and the controversy involved in the surface environment. Moreover, as the geochemical response of tectonic activities and climate change events, the lithium isotopic characteristics in the surface environment reflecting regional tectonics, climatic change, and the degree of continental weathering have the potential to be a quantitative index for calculating the CO2 consumption of continental weathering. In addition, lithium isotopes in salinology are mainly used to trace source material; however, they should be combined with other tracer elements to jointly probe the source of lithium resources and prospect problems. Nevertheless, whether the isotopic compositions of salt lake sediments or brine can be utilized to quantitatively calculate the CO2 consumption of continental weathering processes, and lay the foundation for a global carbon sink and the related paleo-climate and paleo-environment, requires further investigation and verification.