硼同位素地球化学应用研究进展

硼的2个稳定同位素(10B和11B)间较大的同位素相对质量差导致自然界明显的硼同位素分馏,加上硼易溶于水和活泼的化学性质,使其在不同的地质环境下具有不同的同位素组成。现已查明自然界硼同位素组成(δ11B)的变化范围为-70‰~+75‰。较负的δ11B值见于非海相蒸发硼酸盐矿物和某些电气石,而较正的δ11B值见于盐湖卤水和蒸发海水。20世纪80年代以来,随着硼同位素测量方法的建立和改进,硼同位素地球化学研究领域不断拓宽。目前,硼同位素已成功地应用于判别沉积环境、示踪地下水污染、研究矿床成因、示踪海水入侵、重建古海洋与古气候条件和研究大陆化学风化等方面。综合概述了硼同位素的分馏机理、硼同位素在自然界的分布及其硼同位素在地球化学领域研究中取得的成果、最新进展以及研究中存在的问题,以促进硼同位素地球化学研究在我国的进一步发展。

PROGRESS OF GEOCHEMICAL APPLICATION OF BORON ISOTOPE

The large relative weight contrast between 10B and 11B leads to an obvious boron isotopic fractionation in the nature. Boron is soluble in water and is chemically active. So, the boron isotopic composition is diverse in different environments. The variation of boron isotope composition (δ11B) in nature ranges between -70‰ and +75‰. The negative δ11B values are found in non-marine evaporite borate minerals and certain tourmalines, while positive δ11B values are common in salt lake brine and evaporated seawater. Since the 1980s, with the establishment and improvement of the measuring method of boron isotope, the geochemical researches of boron isotope are increased rapidly. At present, the boron isotopes are successfully applied to determine depositional environments and ore genesis, trace groundwater pollution and seawater intrusion, reconstruct ancient marine environment and study continental chemical weathering, etc. This paper studied the mechanism of boron isotopic fractionation, summarized the distribution of boron isotope in nature, reviewed the achievements and the problems, and finally proposed the research direction of boron isotope in geochemical fields, in order to shed some lights on the further development of boron isotope in the future.