江西相山潜火山岩中淬冷包体的发现及其成因机制探讨

在江西相山大型塌陷式火山盆地北部的潜火山岩岩墙中，笔者发现了闪长质的岩石包体，这种包体具典型的反向脉及淬冷边，且淬冷边内含有大量针状磷灰石。在包体内部或包体与寄主岩的边界均见有钾长石及斜长石捕虏晶，这种捕虏晶是包体岩浆从寄主岩岩浆中捕获的，常被熔蚀成筛状或浑圆状。包体与寄主岩（次斑状花岗闪长岩）的稀土元素曲线和不相容元素蛛网图的形态非常相似。因此，相山潜火山岩岩墙中的闪长质岩石包体是不同成分、不同温度的岩浆经对流及不均一岩浆混合作用而形成，在成因类型上属淬冷包体。

Discovery of Quenched Enclaves in Subvolcanic Rocks in Xiangshan, Jiangxi Province and Its Genetic Mechanism

Dioritic enclaves were discovered by the authors in the subvolcanic rock dike of the northern part of the large collapse volcanic basin in Xiangshan, Jiangxi Province. These enclaves have a typical back vein and a quenched margin,and contain a large number of acicular apatites. Potassium feldspar and plagioclase xenocrysts are seen within these enclaves and the boundary between the host rock and the enclaves. These xenocrysts are trapped from the host magma by the enclave magma and are frequently resorbed into a round and sieve shape. There are many similarities of the REE distribution patterns and incompatible element patterns between the enclave and the host rock ( subvolcanic porphyric granodiorite ). Therefore , the quenched dioritic enclaves in subvolcanic granodiorite in Xiangshan were formed by the convection of the magma with different composition and temperature and by the heterogeneous mingling between them. These enclaves are genetically quenched enclaves.