晋冀内蒙交界地区麻粒岩地体中两条花岗岩带及其对早前寒武纪地壳生长的意义  

Two Linear Granite Zones in Shanxi Hebei Nei Mongol Juncture Region and Their Implication for Early Precambrian Continental Evolution

作　　者：翟明国[1] 李永刚[1] 郭敬辉[1] 张雯华[1] 阎月华[1] 

机构地区：[1]中国科学院地质研究所

出　　处：《岩石学报》1996年第2期299-314,共16页Acta Petrologica Sinica

基　　金：国家自然科学基金

摘　　要：晋冀内蒙太古宙地区大面积出露的是英云闪长质片麻岩，也有一些花岗质片麻岩或混合片麻岩，以及很有限出露的紫苏花岗岩。两条线性分布而不是面状分布的花岗岩带引人注目的在区内穿过，无论在产状、构造、围岩特征和岩石组合特征上都在华北克拉通与众不同。这两条花岗岩带在本文中分别被称为凉城－土贵乌拉石榴花岗岩带和桑干钾质花岗岩带。凉城－土贵乌拉石榴花岗岩带发育在孔兹岩系内部，沿韧性剪切带及其两侧分布。岩带的中间部位，断断续续出露一系列的变质辉长岩－辉石岩的透镜体。在石榴花岗岩带的外侧，则与孔兹岩在成分、矿物组成、结构构造上逐渐过渡，没有明确的截然界限。石榴花岗岩与孔兹岩有密切成因联系，具有陆内Ｓ型花岗岩的地球化学性质。桑干构造带花岗岩带是以花岗岩为主的古老剪切带，其内构造混杂有包括高压麻粒岩和退变榴辉岩的不同岩片和透镜体。该带分隔了怀安古陆和恒山古陆。钾质花岗岩以一系列的岩席、岩株和小侵入体，从山西繁峙县向北东一直到河北宣化县，断续相连，北东东向延伸近２００ｋｍ，延伸方向与区域片麻理和主构造线方向一致。它们的常量和微量元素地球化学性质与显生宙碰撞型壳熔花岗岩相似。在空间分布上明显受桑干构造带控制。本区两条线状分布的花岗岩带，?Granitic rocks are extensively developed in North China craton. They represent important early Precambrian geological events, record the history of cratonization of North China. The dominant granitic rocks in Shanxi Hebei Nei Mongol juncfure region are tonalitic gneisses and some calic alkaline granitic gneisses or magmatic gneisses and a minor amount of charnokites. Two linear granite zones noticeably occur in this region. They are quite different from other early Precambrian granitic rocks in North China craton in occurrence, host rocks, structure and rock association, and perhaps represent an important geotectonic unit between different old massifs or tectonism of the lower continental crust. These two linear granite zones are called Liangcheng Togrog Ul garnet granite zone and Sanggan granite zone. The Liangcheng Togrog Ul garnet granite zone occurs in the metamorphosed sedimentary sequence (khondalite series), which is closely related with the two large scale ductile shear zones cutting from Liangcheng to Xinghe and from Zhuozi to Jining. The garnet granite zone occurs only along the shear zones. In the core part of the zones there are a series of lenses of metamorphosed gabbro peroxenite. In the outer part of the zones, garnet granites are gradually changed into khodalitic rocks. Between the granite and khodalite no clear boundarys found. The characteristics of garnet granite zone are (1) linear occurrence; (2) the close space association of garnet granite, gabbro lenses and shear zone; (3) the petrogenetic relation between garnet granite and khondalite, and (4) geochemistry of intraplate S type granite. The Sanggan granite zone is composed a series of granitic gneisses and small granite sills, which were strongly deformed and tectonically associated with different rock slabs and lenses including typical high pressure granulites and retrograde metamorphic eclogites. This granite zone occurs from Yingxian to Xuanhua 200 km in length and ENE trending consistent with regional gneiss foliation.

关 键 词：麻粒岩 地体 花岗岩带 早前寒武纪 地壳生长 

分 类 号：P588.346[天文地球—岩石学] P534.41[天文地球—地质学]