地幔柱构造、大火成岩省及其地质效应

MANTLE PLUMES, LARGE IGNEOUS PROVINCES AND THEIR GEOLOGIC CONSEQUENCES

地幔柱是源于核幔边界或上下地幔边界的热异常物质 ,其隐含的巨大能量导致地幔的大规模熔融和大火成岩省的形成。不同时代的科马提岩和苦橄岩的地球化学性质表明地幔柱源区经历了由太古宙时的亏损源区向现代OIB型源区演化的历程 ,可能与壳幔再循环强度的不断增加有关。地幔柱活动和大火成岩事件与大陆裂解 ,全球气候变迁 ,生物灭绝事件 ,磁极倒转和一些大型矿产资源的形成均有密切的联系。文中还介绍了中国开展地幔柱和大火成岩省研究的概况。

Mantle plumes are thermally anomalous materials and arise from the core-mantle boundary or the upper-lower mantle boundary. Huge energies involved in the starting plumes result in the large-scale melting of the deep mantle and the formation of large igneous provinces in surface. Geochemical studies of komatiites and picrites of different ages suggest that the source of mantle plumes during the Archaean was dominated by depleted MORB-type mantle, and this type of mantle was gradually replaced by enriched OIB-type mantle during the Proterozoic. Such an evolution could be related to increasing frequency and intensity of crustal recycling during the Phanerozoic. Continental break-up, climatic change, mass extinctions, reversal of magnetic field and formation of some large mineral deposits are somewhat temporally related to mantle plume activities and generation of large igneous provinces. Finally, a brief review is made on the current investigation on mantle plumes and large igenous province in China.