造山带碳酸岩起源与深部碳循环

发布时间：2018-11-20 04:38

【摘要】：碳酸岩是揭示地幔地球化学动力学的"探针岩石",迄今有关碳酸岩的研究集中在裂谷环境,而鲜见造山带地区碳酸岩研究的报道。在四川攀西喜马拉雅期造山带、秦岭造山带和华北中央造山带内均有碳酸岩产出,且蕴藏了大型稀土和钼矿床,是研究深俯冲、壳-幔作用和深部碳循环的理想实验室。传统观念认为碳酸岩形成于裂谷环境与地幔柱活动相关,而造山带碳酸岩很可能是陆源富碳沉积物俯冲至地幔低程度熔融的产物。中国造山带内碳酸岩地球化学研究均显示了地壳物质对碳酸岩地幔源区的贡献,这暗示地表碳俯冲至深部地幔,交代地幔发生熔融,这不仅为较还原的地幔源区提供富氧成分,还可以使碳酸岩的母体岩浆更富集稀土,形成稀土矿床。
[Abstract]:Carbonatite is a "probe rock" to reveal the geochemical dynamics of mantle. So far, the study of carbonatite is concentrated in the rift environment, but there are few reports on carbonatite in orogenic belt. Carbonatite is produced in the Himalayan orogenic belt, Qinling orogenic belt and central orogenic belt of North China in Panxi, Sichuan Province, and contains large rare earth and molybdenum deposits. It is an ideal laboratory for the study of deep subduction, crust-mantle interaction and deep carbon cycle. It is believed that carbonatite formed in the rift environment is related to mantle plume activity, while carbonatite in orogenic belt is probably the product of subduction of continental carbon-rich sediments to low melting of mantle. The geochemical study of carbonatite in the orogenic belt of China shows the contribution of the crustal material to the carbonate mantle source, which implies that the surface carbon subducts to the deep mantle and the metasomatic mantle melts, which not only provides the oxygen-rich composition for the reduced mantle source. It can also enrich the parent magma of carbonatite and form rare earth deposits.
【作者单位】：北京大学地球与空间科学学院造山带与地壳演化重点实验室;
【基金】：国家重点基础研究发展计划项目(2013CB429800) 国家自然科学基金资助项目(41573033)
【分类号】：P588.245;P61;P595

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