大陆溢流玄武岩的地球化学特征及起源

快速上涌的大陆溢流玄武岩（CFB），与大陆裂开存在密切的成因关系。CBF总体岩石及地球化学成分均一，富集同位素及不相容元素，但一些样品含有明显的亏损成分，反映出普遍的地幔不均一性，来自上下地幔边界及软流圈的地幔柱提供了CFB所需的主要物质和能量来源，地壳混染作用对CBF的成分影响不大，而受俯冲带脱水流体以及热地幔柱自身与围岩发生的交代作用影响。交代岩石圈地幔对CBF产生重要影响，很好地解释了CFB所具备的微量元素和同位素特征。

GEOCHEMICAL FEATURES AND ORIGIN OF CONTINENTAL FLOOD BASALTS

A close genetic relationship is present between the rapidly upwelling continental flood basalts (CFB) and the continent rift. On the whole, the petrologic and geochemical compositions are homogeneous and enriched with isotopes and incompatible trace elements. However, some samples contain conspicuous depleted compositions, reflecting a general mantle heterogeneity. The mantle plume originating from upper/lower mantle boundary or asthenosphere might have served as the major materials and energies required for CFB that has not been fully assimilated by the crust. The metasomatism between the dehydrated fluid in the subduction zone or the thermal mantle plume itself and its wall rocks determines that the metasomatic lithosphere mantle with a great effect on the formation of CFB, is a major cause of the trace elements and isotope characteristics of CFB.