试论地幔柱构造与川滇西部古特提斯的演化

基于全地幔对流(MOMO模式)提出的地幔柱构造理论将人们对地球深部的认识延伸到核幔边界.它和主要揭示地球表层构造的板块构造理论一起,为认识地球深部过程和大陆裂解等提供了新思路.在早古生代时期川滇西部古特提斯域几个大陆地块从位于赤道附近的冈瓦纳联合古大陆上裂解后又拼合到一起.该地区广泛分布的地幔柱活动产物和引起的浅表地质响应与特提斯的演化有很好的时空耦合关系,证明其间可能存在一个特提斯超级地幔柱,它可能是导致特提斯演化的原动力.根据古地磁资料和地幔柱活动的火成岩记录,认为特提斯超级地幔柱开始活动于晚志留世,结束于晚二叠世,历时约170 Ma.其幕式活动造成了3个陆块先后裂解脱离扬子地块,形成3个特提斯大洋和峨眉山大火成岩省.

Mantle Plume Tectonics and Tethyan Evolution:A Preliminary Interpretation in Sichuan and Western Yunnan Provinces

Mantle plume tectonics based on whole-mantle convection(MOMO model) , along with plate tectonics provides a new hypothesis for the interpretation of earth deep processes and continental break-up. Within palaeo-Tethyan area, the continental blocks located in Sichuan and western Yunnan provinces experienced splitting from the united Pangea super-continent from Late Silurian to Late Permian and aggregation from Early Permian to Late Triassic. The widespread plume-related igneous products, together with surface responses correspond with the evolution palaeo-Tethyan both temporally and spatially. Thus it implies that there was a super-mantle plume and could have provided driving force to cause continent brokeup. The Tethyan super-mantle plume that initiated at late Silurian and died out at Late Permian, with a time span of -170 Ma that caused three blocks to split from Yangtze block and formed three oceans, and the Emeishan large igneous province by its episodic activities, based on integration of palaeogeomagnetic data and plume-related igneous rocks.