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我们首次在湖南发现了钾镁煌斑岩。这套岩石由于遭受强烈风化和蚀变,与典型的西澳钾镁煌斑岩相比,其K_2O和MgO含量明显偏低,Al_2O_3含量偏高。REE含量、金云母成分及以金云母作为主要载体的元素(如Rb、Ba、Ti、Sc、Zn、Ga和Nb等)都与西澳的钾镁煌斑岩基本一致,此外高度富集LREE和U,Th、Nb、Ta、Zr等不相容元素,并有高的δ~(18)O‰值,表明形成这套岩石的上地幔源区受到了软流圈的交代作用。
For the first time, we found the lamproas in Hunan Province. Due to intense weathering and alteration, this rock has significantly lower K 2 O and MgO content and higher Al 2 O 3 content than the typical western Australian lamproites. REE content, phlogopite composition and the elements with phlogopite as main carrier (such as Rb, Ba, Ti, Sc, Zn, Ga and Nb) are basically the same as those of western Australia. In addition, And U, Th, Nb, Ta, Zr and other incompatible elements, and have high δ ~ (18) O ‰ values, suggesting that the upper mantle source zone forming this set of rocks was interbedded with asthenosphere.