地壳风化系统中的Sr同位素地球化学

近20年来，人们利用Rb－Sr同位素体系对地表－近地表地球化学过程、尤其是水圈－岩石圈之间化学物质的循环进行了广泛而深入的研究。大陆地壳风化物质以及地表径流的Sr同位素组成变化揭示了不同流域盆地的地质背景和风化作用的特征。古海洋的Sr同位素组成变化则是地壳和地幔演化以及不同地质历史时期壳－幔相互作用的共同结果。本文对地壳风化系统Sr同位素地球化学研究的全面而详细的综述表明，Rb－Sr同位素体系仍将是研究地壳风化、水圈－岩石圈之间化学物质循环的重要手段，根据古海水及其化学沉积物的Sr同位素记录研究壳－幔演化和地球圈层演化过程中的物质循环特征以及地表古环境变化将是本研究领域的重点。

GEOCHEMISTRY OF STRONTIUM ISOTOPES IN THE CRUST WEATHERING SYSTEM

In recent 20 years, the geochemical processes on the surface or/and near the surface of the earth, especially the chemical circulation of materials between the hydrosphere and the lithosphere have been well documented in terms of the Rb-Sr isotope systematics. The isotopic composition of Sr in weathering products of the continental crust and surface runoff can reveal the geological background and weathering characteristics of different drainage basins. The variation of Sr isotope in paleo-ocean is regarded as the result of the evolution of crust and mantle and of the crust-mantle interaction in different geological times. Detailed geochemical studies on strontium isotopes in the crust weathering system in the present work show: (1) the Rb-Sr isotope systematics is still important in studying the weathering of the crust and the chemical circulation of materials between the hydrosphere and the lithosphere; (2) research work in this field should be focused on the evolution of the crust and mantle, changes in the paleo-environment on the surface and characteristics of material circulation during the evolution of the geospheres on the basis of the Sr isotope records in the paleosea water and its chemical sediments.