非洲乍得盆地玄武岩K-Ar和^39Ar-^40Ar年代学及其动力学背景  

K-Ar and ^(39)Ar-^(40)Ar Geochronology of Basalts from the Chad Basins,Africa and Its Geodynamics Setting

作　　者：路玉林[1,2] 刘嘉麒[1] 窦立荣 郭正府[1] 肖坤叶 胡勇 杜业波 孟凡超[1] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]安徽省地质调查院,合肥230001 [3]中国石油天然气勘探开发公司,北京100034

出　　处：《地质学报》2009年第8期1125-1133,共9页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号40772050、40773023);中国石油天然气集团公司科技攻关项目(编号04B60204)的资助成果

摘　　要：乍得的Doba、Bongor和Lake Chad盆地是早白垩世中非右行走滑应力场控制下形成的一系列中新生代陆内拉分盆地,形成与中、赤道及南大西洋打开有关。钻井揭示了盆地内分布有大量的中新生代玄武岩。系统的K-Ar、Ar-Ar法年代学研究发现,至少可识别出2个周期的火山活动旋回,即:①95～75Ma,只分布于Doba盆地;②66～52Ma,分布于Bongor和Lake Chad盆地。研究表明,乍得盆地内中新生代火山活动是板内伸展应力机制下的产物,与白垩纪整个西中非地区的区域构造背景相一致,岩浆作用与裂谷作用密切相关。Doba, Bongor and Lake Chad basins in Chad are a series of the intra-continental rifted basins resulted from and controlled by the dextral strike-slip stress field along the Central African Shear Zone during Mesozoic-Cenozoic time. Their formation is likely related to the opening of the central, equatorial and south Atlantic oceans. The borehole data reveal a wide distribution of Mesozoic-Cenozoic basalts throughout the basins, but they are poorly documented. A detailed chronology study shows that at least two periodic magmatic activities in the study areas can be recognized using K-Ar and Ar-Ar methods： （1） 95- 75 Ma only in the Doba basin; （2） 66-52 Ma, well expressed in the Bongor basin and Lake Chad basin. The research shows that the Mesozoic-Cenozoic volcanic activities in Chad basins are the products of the intraplate extensional stress regime, corresponding to the tectonic setting of the whole West and Central African during Cretaceous. Magmatism is closely correlated with rifting.

关 键 词：玄武岩 中新生代 乍得盆地 非洲 

分 类 号：P597.3[天文地球—地球化学]