【摘要】 目前关于地幔柱存在与否的争论主要集中在地幔柱学说的三个假设上:(1)起源于地球核幔边界缓慢上升的细长柱状热物质流;(2)热点下具有异常高温地幔;(3)地幔柱是相对静止的。这三个方面的验证需要今后深部地球物理探测、岩石学和古地磁等学科的综合运用和进一步的工作。文中认为,地幔柱学说依然能合理地解释地球上一级地质现象,反对地幔柱的学者过分强调了一些小尺度的与地幔柱理论不符的细节,而小尺度地壳特征显然还受到其他许多因素的影响。可以从以下5个方面来鉴别老地幔柱:(1)大规模火山作用前的地壳抬升;(2)放射状岩墙群;(3)火山作用的物理特征;(4)火山链的年代学变化;(5)地幔柱产出岩浆的化学组成。研究表明,峨眉山大火成岩省满足其中的3到4个指标,因此地幔柱是形成峨眉山玄武岩的主要动力学机制。更多还原

【Abstract】 Current debates over mantle plumes are centered on three assumptions namely: (1) cylindrical thermally-anomalous materials which arise from the core-mantle boundary; (2) high temperature of mantle plumes; (3) mantle plumes are stationary. A full test of the validity of these assumptions requires a comprehensive evaluation using techniques including high-resolution seismic tomography, petrology and paleomagnetism. It is argued in this paper that the plume hypothesis can fairly well explain first-order geologic observations. Geoscientists against the plume hypothesis often tend to over-emphasized some details that may be also influenced by other factors, in addition to mantle plumes. Five criteria can be used to identify ancient mantle plumes: (1) crustal uplift prior to volcanism; (2) dyke swarms; (3) volcanic chain; (4) physical characteristics of volcanism and (5) chemical characteristics of plume-derived basalts. Our investigation shows that at least three, and perhaps, four of these criteria are met for the Emeishan large igneous province, suggesting that a mantle plume played a central role in the generation of the Emeishan basalts.更多还原