内蒙古苏尼特左旗早白垩世宝德尔花岗岩伸展穹隆的确定及其地质意义  

The identification of Early Cretaceous Baoder extensional granitic dome in Sonid Left Banner, Inner Mongolia, and its tectonic implications

作　　者：郭磊[1,2] 李建波[3] 童英[1] 王涛[1] 莫南[1,4] 曾涛[3] 焦永艳 

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]中国地质调查局三维地质调查研究中心,北京100037 [3]东华理工大学,江西南昌330013 [4]中国地质大学(北京),北京100083

出　　处：《地质通报》2015年第12期2195-2202,共8页Geological Bulletin of China

基　　金：国家重点基础研究发展计划(973计划)课题(编号:2013CB429803);国家自然科学基金项目(批准号:41372006);中国地质调查局项目(编号:12120115069701)

摘　　要：内蒙古宝德尔穹隆是发育在苏尼特左旗中蒙边境地区的不对称同构造伸展穹隆。该穹隆由内向外由核部早白垩世花岗岩、边缘韧性剪切带和脆性拆离断层组成,上盘为未变形的早二叠世花岗闪长岩、泥盆系片岩和早白垩世盆地,韧性剪切带和拆离断层仅发育在穹隆西南部。区域构造解析和显微构造分析表明,岩体侵位和韧性剪切带形成于同一构造应力场,指示上盘统一向NW方向剪切,变形程度由未变形的岩体核部向外侧逐渐增强,面理的形成与岩体的侵位和隆升过程密切相关。因此,该穹隆和东北亚其他岩浆穹隆相似,是不对称的花岗岩穹隆,反映了区域伸展拆离环境下侵位的同构造花岗岩穹隆的特点。Located in the China-Mongolia border area of Sonid Left Banner, the Baoder dome is an asymmetric syn-kinematic extensional dome. This dome consists of core Early Cretaceous granitic pluton, ductile shear zone and brittle detachment fault from center outwards. The hanging wall consists of undeformed Early Permian granodiorite, Devonian schists and Early Cretaceous basin.Ductile shear zone and detachment fault are only developed in the southwestern part. Detailed field observation and microstructures show that core pluton and ductile shear zone were formed in the same tectonic stress field, suggesting a unified top-to-the-NW shearing. The deformation grade increases outwards. All these characteristics imply that the foliations of the dome were genetically closely related to the emplacement and uplift of the pluton. Thus, the Baoder dome is similar to other extensional domes in Northeast Asian, which reflects geological features of syn-kinematic granitic dome during the regional extensional detachment setting.

关 键 词：不对称花岗岩穹隆 同伸展侵位 晚中生代伸展 苏尼特左旗 

分 类 号：P534.53[天文地球—古生物学与地层学]