冀北承德地区孤山二长闪长岩及其包体与捕虏体的岩石学与地质意义

承德大庙地区的孤山闪长岩体是前寒武纪大庙斜长岩杂岩体伴生的岩体，其内含有不同类型的暗色包体以及超镁铁—镁铁质杂岩型捕虏体。孤山闪长岩体主要岩性为二长闪长岩，岩体含有二长闪长岩、黑云母辉石角闪石岩和斜长角闪岩型包体以及超镁铁—镁铁质杂岩型捕虏体。超镁铁—镁铁质杂岩由黑云母辉石角闪石岩、斜长角闪岩、含有辉长闪长岩包体的大理岩等组成。孤山二长闪长岩体、包体和杂岩捕虏体普遍经历了绿帘角闪岩相变质，典型变质反应Cpx+Pl+H₂O→Amp₂+Ep+Ab±Chl。二长闪长岩体和包体中的角闪石有早、晚两期，早期角闪石是岩浆原生的，晚期变生角闪石与绿帘石围绕原生单斜辉石环带状生长，是由单斜辉石变生的。孤山二长闪长岩属于正常类型SiO₂不饱和岩石与偏铝质岩石，富集大离子亲石元素（如Sr、Ba和K）、亏损高场强元素（如Th、Nb、Ta、Zr、Hf和Ti），Rb和Y含量低，相容元素Ni、Cr含量低，V高，轻稀土富集，轻重稀土分异明显，Eu轻微正异常。与太古代TTG、高镁闪长岩、典型的赞歧岩类、芬兰和西格陵兰岛闪长岩、美国纽约州铁闪长岩以及西藏中生代的泽当闪长岩的对比研究表明，孤山二长闪长岩与西藏泽当闪长岩非常相似，微量和稀土元素具有赞歧岩质闪长岩的特点，应是俯冲环境产物。本研究对认识大庙斜长岩杂岩体的成因以及冀北地区构造演化有重要意义。

Petrology and its geological significance of Gushan monzodiorite pluton and its enclaves and xenoliths in Chengde area,northern Hebei Province

The Gushan diorite pluton in the Damiao area of Chengde City is associated with the Precambrian Damiao anorthosite complex, which mainly consists of diorite and different types of dark enclaves and ultramafic-mafic complex-typed xenoliths. The main lithology of Gushan diorite pluton is monzodiorite, which contains monzodiorite, biotite-pyroxene-hornblendite and plagioclase-amphibolite enclaves and ultramafic-mafic complex-typed xenoliths. The ultramafic-mafic complex-typed xenoliths consist of biotite-pyroxene-hornblendite, plagioclase-amphibolite, marble with gabbro-diorite enclaves, etc. The Gushan diorite, as well as its enclaves and complex-typed xenoliths generally experienced the metamorphism of the epidote amphibolite facies, the typical metamorphic reaction is Cpx+Pl+H2O→Amp2+Ep+Ab±Chl. Among them, the hornblendes in the monzodiorite have two types, primary hornblendes and metamorphic hornblendes growing in a zonal pattern around the clinopyroxenes which were formed by the metamorphic reaction of clinopyroxene. Chemical compositions of Gushan monzodiorites belong to extreme and low-degree SiO2 unsaturated rocks of normal type, which enriches large ion lithophile elements (Sr, Ba and K), depletes high field strength elements (Th, Nb, Ta, Zr, Hf and Ti) and has low Rb and Y content. The compatible element Ni and Cr contents are low and V content is high. The LREEs are enriched, the LREEs and HREEs are clearly differentiated, and Eu has slight positive anomaly. Through the comparative studies of Gushan monzodiorite with Archean TTG, high-Mg diorite, typical sanukitoids, monzodiorite in Finland and West Greenland, Nain ferrodiorite in New York and Zedang diorite in Tibet, it is shown that Gushan monzodiorite with the characteristics of sanukitoids in the geochemistry of trace elements and rare earth elements is very similar to Zedang diorite and should be the products of subduction environment. This study is of great significance to understand the genesis of Damiao anorthosite complex and the tectonic evolution in northern Hebei Province.