闽东南基性岩脉形成的构造应力场地质意义  

GEOLOGICAL IMPLICATIONS OF TECTONIC STRESS FIELD FORMED IN MAFIC DIKES IN SOUTHEASTERN FUJIAN

作　　者：张贵山[1,2] 温汉捷[1] 胡瑞忠[1] 裘愉卓[1] 杨光树[1] 于文修[1] 

机构地区：[1]中国科学院地球化学研究所矿床地球化学重点实验室 [2]中国科学院研究生院,北京100039

出　　处：《大地构造与成矿学》2006年第2期142-148,共7页Geotectonica et Metallogenia

基　　金：中国科学院知识创新工程项目(KZCX3-SW-125;KZCX2-102)资助.

摘　　要：闽东南沿海地处长乐-南澳构造带内,发育晚中生代以来的基性岩脉(岩群),其几何形态和产状记录着区域应力场活动。通过对漳浦赤湖和东山海边基性岩脉的几何形态和产状的分析,推测长乐-南澳带在白垩纪为左旋韧性剪切带,古新世转变成左行脆性剪切带。长乐-南澳带的左旋走滑活动,是由古太平洋板块朝NW斜向俯冲引起的。晚白垩世以来,闽东南应力场性质为剪切与拉张相互变换,指示地壳拉张不是连续的,而是分期次;晚白垩世以来大洋板块属于低应力型俯冲,拉张是东南部主构造。The coastal area around Southeastern Fujian is located in the Changle-Nan＇ao tectonic zone, where mafic dikes （swarms） were developed since late Mesozoic. To prove the popular view that the geometrical form and occurrence of mafic dikes should record the evolution of local stress field, a study was carried out on the mafic dikes from Chihu of Zhangpu and Haibian of Dongshan, and it was found that the Changle-Nan＇ao tectonic belt might be a levorotatory ductile shear zone in the late Cretaceous, but was thereafter converted to the lefthanded fragile shear zone in the Paleocene; We believe that this was caused by the NW-trending subduction of the paleo-Pacific plate. Since late Cretaceous, the stress changes between shearing and tension in Southeastern Fujian, which indicates that the crustal extension is not continuous but proceeded by many stages; Through the low stress subduction of oceanic plate, crustal extension has dominated in Southeastern China.

关 键 词：基性岩脉 拉张 左旋走滑 剪切带 长乐-南澳带 闽东南 

分 类 号：P542[天文地球—构造地质学]