中文摘要：

认识地幔组成不均一性及其成因对于揭示固体地球的演化规律具有重要意义。简要论述了全球典型大洋玄武岩（洋岛／海山玄武岩（0IB）、洋中脊玄武岩（MORB））源区组成不均一性的化学特征及成因，并分析了国内外对地幔组成不均一性的认识不足之处和原因。30多年以来，玄武岩地球化学研究主要围绕地幔组成端元成分差异性及其成因，包括HIMU（‘μ’=”238U／204Pb）、EMI和EMII及FOz0（同位素组成介于HIMu和MORB之间）富集端元，以及DMM亏损地幔端元（包括印度洋型（Indian-typeMORB）和太平洋型（Pacific-type MORB）。富集地幔端元通常被认为与板块构造导致的地球化学循环有关，然而，这些端元的成因存在多解性。尽管过去常将亏损地幔作为一个地幔端元，但全球主要地幔库的亏损端元之间的同位素差别也是长期演化的结果，地幔亏损端元组成差异的研究也是至关重要的。地幔端元成因的多解性主要是由于对板块构造导致物质循环的关键环节了解不够，以及对地球早期熔融导致的上地幔亏损过程的认识不足。在总结研究现状和科学问题的基础上，本文指出地幔不均一性成因研究的潜力方向和方法：（1）深化对玄武质洋壳深部地幔压力下的物理化学相变研究，认识再循环洋壳重返浅部地幔的基本理论前提；（2）利用年轻的大陆裂张海盆玄武岩，有效检验大陆富集物质是否拆离进入地幔软流圈；（3）碳酸岩熔体来源及其对碱性玄武岩富集端元组成的贡献；（4）板块俯冲进入地幔过程中化学分异过程。

英文摘要：

It is crucial to study the nature and origin of the mantle heterogeneity for understanding the solid Earth evolution. In this study we evaluated the mantle heterogeneity through oceanic basalts, e. g. , ocean island basalts （OIBs） and mid-ocean ridge basalts （MORBs）, and discussed the reason for insufficient un- derstandings of the mantle heterogeneity. Studies in the past three decades show that the enriched mantle end-members include HIMU （（ ＇μ ＇ = 238 U/204 Pb） （low 87 Sr/86 Sr and high 206 pb/204 Pb））, EMI （medium 87 Sr/86 Sr, low 206 pb/204 Pb）, EMII （high 87 Sr/86 Sr, medium 206 pb/204 Pb）, FOZO, and depleted mantle endmember of DMM （including Indian-type and Pacific-type）. Origins of enriched mantle end-members are supposed to be related to plate tectonics, such as oceanic plate subduction, continent rifting and detach- ment. However, the origin of compositional differences between the end-members remains highly contro- versial. We consider that studies on depleted mantle end-members are also important for understanding the diversity of the compositions of mantle end-members. Debates on the origin of mantle end-members are mainly caused by lack of knowledge on the role of plate subduction in driving geochemical cycling and the mantle depletion in the early stage of melting of the Earth. We, therefore, suggest the following study as- pects： Firstly, phase transition and the fate of subducted oceanic plate in the lower mantle; Secondly, test if detached continental crust can be mixed into the upper mantle due to continent rifting; Thirdly, the role of carbonate in the genesis of alkali basalts; Fourthly, the geochemical fractionation of subducting oceanic plate in the mantle.