西秦岭糜署岭岩体镁铁质微粒包体的特征及成因

糜署岭岩体的岩石组合为灰白色似斑状二长花岗岩-花岗闪长岩-石英闪长岩，其中镁铁质微粒包体十分发育。包体密集成群、成带状分布，个体大小悬殊且有定向性。有的包体具有细粒边，有的见冷凝边；包体与寄主岩石在成分、色率以及组构上多呈弱过渡关系，界线模糊；包体中发育斜长石异常环带及针状磷灰石，常有寄主岩石中的钾长石巨晶(捕虏晶)。这些特征提供了基性岩浆与酸性岩浆混合的证据，也为探讨本区中生代壳幔混合作用和地壳增生提供了信息。

Features and origin of mafic microgranular inclusions in the Mishuling intrusion in the West Qinling

The host rocks of the Mishuling intrusion consists of a grayish white porphyritic monzogranite-granodiorite-quartz diorite,in which mafic microgranular inclusions are well developed.The in clusions are close-spaced and occur in swarms and zones.They are highly varied in size and display preferred orienta-tion.Some of them have fine-grained rims and chilled borders.The inclusions commonly exhibit grada-tional contact relationships with their host rocks in respect to the composition,color index and fabrics,the boundaries being vague.Acicular apatite,K-feldspar megacrysts(xenocrysts),rimmed structure as well as abnormal zoning of plagioclase can be observed in most of the inclusions.These features suggest that the Mishulin g intrusion formed by mixing of basic magma and acid magma.This offers important evidence for the determination of the regional tectonic boundary and tectonic units and also furnishes new information for the study of Mesozoic crust-mantle mixing and crustal accretion in the study area.