华北板块北缘东段晚二叠世构造属性:小梨河高分异Ⅰ型花岗岩地球化学的制约  

Later Permian epoch tectonic attribute of the eastern segment of the northern margin of North China plate: constraints from geochemistry of highly fractionated I-type granites in Xiaolihe Area

作　　者：李超[1] 马超[1] 刘东伟[1] 贾海明[1] 黄健[1] LI Chao MA Chao LIU Dong-wei JIA Hai-ming HUANG Jian(Geological Survey of Jilin Province, Changchun 130061, Jilin, China)

机构地区：[1]吉林省地质调查院,吉林长春130061

出　　处：《吉林地质》2016年第3期6-11,共6页Jilin Geology

基　　金：中国地质调查局项目(12120114069801)资助

摘　　要：小梨河正长花岗岩岩体位于华北板块北缘东段。岩体富硅、钾、钠,高铝,低镁、磷,P_2O_5与SiO_2呈负相关,铝指数A/CNK为0.91~1.23,分异指数为78.98~89.02,属高分异I型花岗岩类。LREE/HREE=10.28~12.91,（La/Yb）_N=10.69~14.87,配分曲线呈不对称右倾形,具有微弱Eu的负异常（δEu=0.64~0.77）;与原始地幔相比,富集大离子亲石元素（LILEs,如Rb、Ba）,亏损高场强元素（HFSEs,如Nb、Ta、P和Ti）,显示火山弧岩浆岩特征;样品在花岗岩构造环境判别图解中均落入火山弧范围内。结合区域研究资料,表明其可能为一种活动大陆边缘弧环境。Xiaolihe syenogranite rock mass are located in the eastern segment of the northern margin of the North China plate. These rocks have high content of silica, potassium and sodium, high alumina, low abundance of magnesium and phosphorus, P_2O_5 decreases with the increasing of SiO_2, A/CNK equals 0.91-1.23, and differentiation index DI is 78.98-89.02, the granites can be classified as highly fractionated I-type granite. LREE/HREE=10.28-12.91, La N/Yb N=10.69-14.87, the chondrite normalized patterns are right declined with a weak negative Eu anomaly（δEu=0.64~0.77）; They are enriched in the large ion lithophile elements（LILEs, e.g., Rb, Ba）, and depleted of the high field-strength elements（HFSEs, e.g., Nb, Ta, P, and Ti）. Combined with regional geological data, the authors hold that the eastern section of northern margin of the North China plate might have been in an active continental-margin setting in the Carboniferous.

关 键 词：华北板块北缘 小梨河 晚二叠世 高分异I型花岗岩 岩石成因 构造意义 

分 类 号：P588.121[天文地球—岩石学]