华北地区晚中生代重大构造转折的地质证据  

The geological evidences for the tectonic transition in late Mesozoic in North China

作　　者：陈根文[1] 夏换[1,2] 陈绍清 

机构地区：[1]中国科学院广州地球化学研究所成矿动力学重点实验室,广东广州510640 [2]中国科学院研究生院,北京100039 [3]重庆川东南地质队,重庆401329

出　　处：《中国地质》2008年第6期1162-1177,共16页Geology in China

基　　金：国家重点基础研究发展规划项目(2006CB403507);中国科学院广州地球科学研究所创新项目(GIGCX-04-03)资助

摘　　要：华北地区在侏罗纪和白垩纪分别发生了两次不同性质的岩浆活动,早期形成一套高锶石英闪长岩,另一期为钾玄岩系。两套岩石分别代表地壳加厚和减薄的构造背景,两次岩浆活动的转折期大致在130Ma左右。此外,华北地区白垩纪广泛分布的碱性岩同样表明区域内在白垩纪曾发生过强烈的岩石圈伸展作用。这一地质特征与区内盆地地震剖面、造山带构造活动年龄、变质核杂岩的年龄、早白垩世太平洋板块运动方向和运动速率的改变以及郯庐断裂左旋运动年龄等地质资料相佐证。因此华北地区岩石圈减薄作用主要发生在早白垩世时期,晚侏罗世—早白垩世是华北地区中生代重大构造发生的转折点。There were two intensive igneous activities m North China. The early stages of magmatism is charecteristized by Jurassic high-Sr quartz diorites and the latter stage is charateristic of Cretaceous shosholites. These rock series represent two different geological setting of crust thichenning and lithospheric thinning, respectively. The transition of two igneous activities occurred at about 130 Ma. The development of Cretaceous alkaline rocks in North China shows that in the lithosphere extension occurred in Cretaceous. This conclusion can also been verified by-seism profile, the ages of extensional and compressional structures, the ages of metamorphose core complexes, strike-slip ages of Tanlu fault zone. The lithosphere extension took place in the Early Cretaceous, and the boundary of Late Jurassic-Early Cretaceous is the tectonic turnning point in North China.

关 键 词：华北地区 中生代 构造转折 岩浆活动 岩石圈减薄 

分 类 号：P547[天文地球—构造地质学]