川滇西部地区钾质煌斑岩特征及其成因

川滇西部地区钾质煌斑岩带产物扬子板块西缘与三江褶皱带之间的过渡地带，侵位于老第三系地层。岩石化学特点具有中等含量钾、钛和钠、铝弱饱和，属岛弧环境的钙碱性煌斑岩与板内环境的钾镁煌斑岩（超钾）之间的过渡类型。微量元素Sr相对于Rb,Ba,K等元素具有明显的负异常，是地幔交代作用的产物。区域上与其伴生的壳源型花岗岩侵位在前，分布于西侧；碱性岩层中；钾质煌斑岩侵位在后，分布于东侧，属反序侵位序列，为喜山期陆壳碰撞、褶皱造山运动所触发的被动地幔作用产物。

CHARACTERISTICS AND ORIGIN OF POTASH LAMPROPIIYRE IN WEST SICHUAN-YUNNAN

The potash lamprophyre belt of west Sichuan-Yunnan is located at the transitional zone between west margin of Yangtze platform and Sanjiang fold belt. It is emphaced in Tertiary strata. The rocks are charcterized by medium content of potassium, titannuium and weak saturation of aluminium. They belong to a transitional type between Island are calci-alkali lamprophyre and intraphate potassium-magnesium lamprophyre. In contrast with Rb,Ba,K,the'trace element Sr has a negative anomaly. This is the product of replacement of the mantle. The regionelly associated crustal granites emplaced earlier are located to the west;the alkali rocks in the middle;the late potash lamprophyre to the east. Theis is a reversed order of replacement. And it is the product of passive mantle reaction detonated by continental collision during Himalayan movement.