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胶北地体中的深层次拆离构造:扬子板片折返的板上响应
引用本文:梁凤华,许志琴,李忠海,陈方远.胶北地体中的深层次拆离构造:扬子板片折返的板上响应[J].岩石学报,2011,27(4):969-979.
作者姓名:梁凤华  许志琴  李忠海  陈方远
作者单位:中国地质科学院地质研究所国土资源部大陆动力学重点实验室,北京,100037
基金项目:本文受地质调查项目(1210823218、1212010711816)和中国地质科学院地质研究所基本科研业务费(J0919)联合资助.
摘    要:通过对胶北地体基底中的韧性变形构造的研究,厘定了位于太古宙胶东群和古元古界粉子山群之间及粉子山群与晚元古界蓬莱群之间的2条深层次韧性拆离断层。显微构造和石英组构研究表明它们的剪切指向自SE向NW,并经历了高温(>650℃)到低温(350℃)的组构演化过程。对剪切带中的长英质糜棱岩进行SHRIMP U-Pb测年,获得153±2Ma和128.5±1.5Ma两组重结晶变形年龄,代表韧性拆离断裂形成及活化的时限。结合地体中岩浆作用、莱阳白垩纪盆地沉积以及制约盆地的韧性拆离断裂(148Ma)等相关伸展构造特征,认为胶北深层次拆离构造是扬子深俯冲板块折返后期的板上伸展的响应。

关 键 词:胶北陆块  板上拆离构造  后造山伸展作用  扬子/华北碰撞造山带
收稿时间:2010/10/20 0:00:00
修稿时间:2011/2/12 0:00:00

Deep-level ductile detachment system in the Jiaobei terrain, eastern China: Deformation response of the overlying plate during the exhumation of Yangtze plate.
LIANG FengHu,XU ZhiQin,LI ZhongHai and CHEN FangYuan.Deep-level ductile detachment system in the Jiaobei terrain, eastern China: Deformation response of the overlying plate during the exhumation of Yangtze plate.[J].Acta Petrologica Sinica,2011,27(4):969-979.
Authors:LIANG FengHu  XU ZhiQin  LI ZhongHai and CHEN FangYuan
Affiliation:Key Laboratory for Continental Dynamics, MLR, Institute of Geology, CAGS, Beijing 100037, China;Key Laboratory for Continental Dynamics, MLR, Institute of Geology, CAGS, Beijing 100037, China;Key Laboratory for Continental Dynamics, MLR, Institute of Geology, CAGS, Beijing 100037, China;Key Laboratory for Continental Dynamics, MLR, Institute of Geology, CAGS, Beijing 100037, China
Abstract:Two large-scale deep-level ductile detachments are identified in the Precambrian basement of Jiaobei block, at the southeast end of North China Craton and nearing the northern Sulu ultrahigh pressure metamorphic belt, eastern China. They are respectively DF1 locating between Archean Jiaodong Group (JD) and Paleo-proterozoic Fenzishan Group (FZS) and DF2 between FZS or JD and Neo-proterozoic Penglai Group (PL). Microstructures and fabrics show the top-to-northwest shear sense and the fabric evolution of quartzite with temperature decreasing. The recrystallized deformation ages are restricted at 153±2Ma and 128.5±1.5Ma by SHRIMP U-Pb dating for mylonitic orthogneiss from DF1, which behalf respectively the forming age and reactive age of detachment. Combining with other extension structures, such as magmatism, sediments of Cretaceous Jiaolai basin and the ductile detachment confining Jiaolai basin (148Ma), we suggest that the large-scale deep-level ductile detachments with top-to-NW shear sense formed during the uplift (late exhumation) extension stage of UHP metamorphic rocks and is kind of intraplate deformed effect of overlying plate during continental deep-subduction of Yangtze plate.
Keywords:Jiaobei block  Ductile detachment on the overlying plate  Extension during post-collision  Continental collision between North China plate and South China plate
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