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大量的大洋玄武岩地球化学和同位素数据都证明了地幔组分中普遍存在着不均一性。最近的研究表明,大洋玄武岩的同位素不均一性甚至出现在微米级尺度上的熔体包裹体中,这进一步证明了地幔存在高度的不均一性。因此,前人基于Sr-Nd-Pb-He同位素组成,提出地幔中存在着四种端元组分,即DMM,EMI,EMII和HIMU。对于不均一过程,一般认为消减和拆沉作用是壳幔物质循环的主要过程——大洋板块和少量的上、下陆壳一起消减下插进入到深部地幔。本文主要介绍四种端元组分的地球化学特征及其成因。
A large number of oceanic basaltic geochemical and isotopic data have demonstrated the widespread heterogeneity in the mantle components. Recent studies have shown that the isotopic heterogeneity of the oceanic basalts even occurs in melt inclusions on the micrometer scale, further confirming the high degree of heterogeneity in the mantle. Therefore, based on the Sr-Nd-Pb-He isotopic composition, the authors propose that there are four kinds of terminal components in the mantle: DMM, EMI, EMII and HIMU. For the heterogeneity process, it is generally considered that the abatement and delamination are the main processes of material circulation in the crust and mantle. The oceanic plate and a few upper and lower continental crusts are reduced and inserted into the deep mantle. This paper introduces the geochemical characteristics of the four kinds of terminal components and their causes.