Termit盆地构造变形的力学机制  

Mechanics of Termit Basin in Central Africa Rift Systems

作　　者：张庆莲[1,2] 侯贵廷[1] 潘校华[3] 万伦坤[3] 毛凤军[3] 

机构地区：[1]北京大学地球与空间科学学院,教育部造山带与地壳演化重点实验室,北京100871 [2]石家庄经济学院资源学院,河北石家庄050031 [3]中国石油勘探开发研究院,北京100083

出　　处：《大地构造与成矿学》2013年第3期377-383,共7页Geotectonica et Metallogenia

基　　金：中石油勘探开发研究院和国家重点基础研究发展计划"973"项目(编号:2009CB219302)联合资助;国家重大专项项目29"海外重点风险项目勘探评价及配套技术";中石油重大专项子课题"被动裂谷成盆机理研究"资助

摘　　要：Termit盆地是中西非裂谷系中典型的中-新生代裂谷盆地,形成于早白垩世大西洋张裂的构造背景下。在白垩纪至古近纪经历了"裂谷-坳陷-裂谷"的构造演化过程,且两期裂陷作用形成的断裂走向不同。依据Termit盆地的基础构造特征,运用弹性有限元数值模拟方法,从动力学角度讨论盆地构造演化模式,为盆地的构造演化研究提供动力学依据。模拟结果表明,在早白垩世,盆地受区域NE-SW向拉张作用,在盆地西部边界发育一系列NW-SE向早白垩世早期断层。在古近纪,盆地受近EW向拉张作用,在盆地西部受早期断层影响较大的Dinga断阶带和Yogou西斜坡地区,局部应力场使断层发育走向为NW-SE;受其影响较小的Araga地堑发育张扭性断层,沿早白垩世断层呈雁行排列;不受其影响的Fana低凸起和Moul凹陷发育NNW-SSE向断层。The Termit basin is a Mesozoic-Cenozoic rift basin developed along the Central African Shear zone, it is formed under the tectonic setting of the opening of the Atlantic Ocean during the Early Cretaceous. The Termit basin underwent three stages of tectonic evolution--＂rift-depression-rift＂ and two phases of rifting that formed two different fault strikes from Cretaceous to Paleogene. Based on the geological setting of the Termit basin, the mechanics of the basin is investigated through the analysis of the stress field using linear elastic theory with two dimensional finite element modeling, through the analysis of the stress field. The modeling results suggest that a series of NW-SE faults were developed at the west part of the Termit basin under the effect of the Early Cretaceous NE-SW regional stress field. The direction of the regional stress changed to nearly W-E in Paleogene. A series of N-S faults were formed at the SE part of basin where there were no pre-existent faults. The change in fault strike from near N-S trending to NW-SE trending in the place that had pre-existent faults was caused by the local stresses of the Early Cretaceous faults.

关 键 词：Termit盆地 中西非裂谷系 东尼日尔 局部应力场 有限元数值模拟 力学机制 

分 类 号：P542[天文地球—构造地质学] P628.3[天文地球—地质学]