【摘要】 桂东北煌斑岩SiO2含量主要在33.74%～48.14%之间,属基性-超基性范围,为钙碱性岩系、钾质-超钾质煌斑岩;地球化学表明,桂东北煌斑岩以富集大离子亲石元素和轻稀土元素,而亏损高场强元素(Ta-Nb-Ti)为特征,轻、重稀土具有较好的分馏。结合元素地球化学和地质发展史研究表明,桂东北煌斑岩为富含稀土元素的俯冲带流体交代过的富集地幔部分熔融所产生的岩浆,在上升过程中受到部分地壳混染的产物。更多还原

【Abstract】 The content of silicon dioxide in the lamprophyres in northeast Guangxi changes from 33.74% to 48.14%,which can be classified as basic to ultra-basic,potassic to ultra-potassic lamprophyre of the calc-alkaline rock series.The geochemical study demonstrates that the lamprophyre dykes are characterized by significant LILE and LREE enrichment but a depletion in HFS elements(Ta-Nb-Ti),there is moderate to strong fractionation between the light and heavy REE.The study of element geochemistry and geological history shows that the lamprophyre formed from the magma derived from partial melting of the mantle with metasomatism of fluids rich in REE in subduction zone,and with contamination of crustal materials in rising process of the magma.更多还原