近年来地幔捕虏体中富硅熔体的研究受到广泛关注,富硅熔体不仅具有多种产出状态,其成因来源也具有多样性.本文选取汉诺坝地区地幔捕虏体矿物中的熔体包裹体和斜方辉石反应边中的熔体玻璃为研究对象,探索富硅熔体在岩石圈地幔演化中的作用.通过详细的岩相学观察并结合电子探针分析发现,二者成因不同.熔体包裹体玻璃成分富硅(SiO261%～65%),相对贫Na2O(1%～3%)、K2O(＜1%),富含挥发份(约3%～6%),为地幔交代成因;斜方辉石反应边玻璃富硅(SiO2 64%～67%)、碱(Na2O 5%～7%,K2O 6%～9%),几乎不合挥发份,是地幔捕虏体被寄主玄武岩浆快速携带上升至地表的过程中两者反应的产物.地幔交代作用产生的富硅熔体包裹体深刻影响了岩石圈地幔的地球化学性质;而玄武岩浆在上升过程中与岩石圈地幔捕虏体中斜方辉石的反应,导致了岩石圈地幔由富硅向贫硅转变,为华北克拉通的破坏提供了证据.%The study on Si-rich melt in mantle xenoliths has been attracting a wide spread attention in recent years. Si-rich melt has not only several kinds of distribution patterns, but also different causes of formation. In order to search the effect of Si-rich melt during lithosphere mantle' s evolution, we chose melt inclusions in mantle xenoliths and glass in orthopyroxene reaction rims from Hannuoba for research objects. Through detailed petrographical observation and electron microprobe analysis, it is indicated that these two melts have different origins. The glass composition in melt inclusions is rich in silica (SiO2 61% ~65% ) and volatile (about 3% ~6% ), and relatively poor in Na2 O (1% ~3% ) and K2 O ( < 1% ). This kind of glass was formed by mantle metasomatism. The glass in orthopyroxene reaction rims riches in silica (SiO2 64% ~ 67% ) and alkali elements (Na2 0 5% ~ 7% and K2O6% ~9%), rarely has volatile. It is the product of interaction between mantle xenoliths and host basaltic magma when magma carrying mantle xenoliths was ascending to earth' s surface quickly. Si-rich melt inclusions which produced by mantle metasomatism deeply influence geochemical properties of lithosphere mantle. Meanwhile the reaction between orthopyroxene within mantle xenoliths and basaltic magma results in lithosphere mantle' s transformation from Si-rich mantle to Si-poor mantle, and provides evidence for destruction of the North China Craton.
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