渤海湾盆地新生代拉张中心迁移的热-流变机制  

Thermal-rheological mechanism of stretching centers migration in Bohai Bay Basin in Cenozoic

作　　者：焉力文 刘琼颖 何丽娟[1,2,3] 武金辉 陈超强 YAN LiWen;LIU QiongYing;HE LiJuan;WU JinHui;CHEN ChaoQiang(State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;University of Chinese Academy of Sciences,Beijing 100049,China;Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing 100029,China;Institute of Geology,China Earthquake Administration,Beijing 100029,China)

机构地区：[1]中国科学院地质与地球物理研究所岩石圈演化国家重点实验室,北京100029 [2]中国科学院大学,北京100049 [3]中国科学院地球科学研究院,北京100029 [4]中国地震局地质研究所,北京100029

出　　处：《地球物理学报》2023年第5期2039-2050,共12页Chinese Journal of Geophysics

基　　金：国家重点研发计划(2021YFA0716002);国家自然科学基金(42074095)共同资助。

摘　　要：在区域拉张应力作用下,岩石圈拉张减薄,减薄的中心地带成为拉张中心,渤海湾盆地新生代期间拉张中心具有自西向东、自南向北的迁移规律.为了探究渤海湾盆地新生代期间拉张中心的迁移与岩石圈热-流变结构的关系,本文在构造-热演化模拟的基础上,对渤海湾盆地各坳陷新生代岩石圈热-流变结构进行了计算.结果表明:渤海湾盆地新生代岩石圈拉张中心的迁移主要受岩石圈流变强度的非均匀性所控制.拉张中心开始位于岩石圈强度最低的济阳坳陷,拉张及伴随的的热冷却过程使得济阳坳陷岩石圈强度增大,并且超过了渤中坳陷岩石圈强度,因此,沙四段时期,拉张中心迁移到了渤中坳陷;沙三段时期,拉张中心迁移到了黄骅以及辽东湾坳陷.这是由于拉张速度较慢时(对于约90 km厚度的岩石圈而言,如果初始地壳厚度>34 km,拉张速度0.5 cm·a^(-1)),拉张初期会造成岩石圈强度的降低,但随着拉张的持续进行,岩石圈整体强度反而增加.孔店组时期,在岩石圈强度较大的冀中及临清坳陷形成拉张中心可能是叠加了其他地质因素(如前期构造、断裂活动、远程应力等)的影响.东营组时期,在岩石圈强度较大的渤中坳陷形成拉张中心,这可能是该时期岩石圈强度同时受到了郯庐断裂带的活动或小规模的地幔对流的影响,导致其实际强度比模拟计算的强度更低,因而使得应变集中在渤中以及辽东湾坳陷.Under the background of regional stretching stress,the lithosphere is thinned,the center area of thinning becomes the stretching center,and the stretching center of the Bohai Bay Basin(BBB)migrated from west to east and from south to north during Cenozoic.To explain the relationship between the migration of the stretching center and the thermal-rheological structure of the lithosphere during the Cenozoic in BBB,based on the simulation of tectono-thermal evolution,the thermal rheological structure of the Cenozoic lithosphere in each depression of the BBB is calculated in this paper.The results show that:the migration of the lithospheric stretching center in the BBB in the Cenozoic is mainly controlled by the heterogeneity of the lithospheric rheological strength.The stretching center starts from the Jiyang depression with the lowest lithospheric strength,stretching and the accompanying thermal cooling process increased the strength of the lithosphere in the Jiyang depression,even exceeding that in the Bozhong depression,which made the stretching center migrate to the Bozhong depression in the fourth member of the Shahejie formation.During the third member of the Shahejie formation,the stretching center migrated to the Huanghua and Liaodongwan depressions.This is because when the stretching speed is slow(for the lithosphere with a thickness of~90 km,if the initial crustal thickness is>34 km,the stretching speed is 0.5 cm·a^(-1)),the strength of the lithosphere will decrease at the initial stage of stretching,but with the continuation of stretching,the overall strength of the lithosphere will increase.During the Kongdian Formation,Jizhong and Linqing depressions,with the stronger lithosphere,became the stretching center,which may be affected by other geological factors(such as previous tectonics,faults,and,remote stress).During the Dongying Formation,the stretching center was formed in the Bozhong depression with high lithospheric strength,which may be that the strength of the lithosphere in this period was affecte

关 键 词：渤海湾盆地 新生代 热-流变结构 拉张中心 构造-热演化 

分 类 号：P314[天文地球—固体地球物理学]