贝加尔裂谷构造发育的主控因素探讨:来自物理模拟的启示  

Discussion on the Main Controlling Factors of the Structure of Baikal Rift:Insights from Physical Modeling

作　　者：王盟楠 李江海[1] 柳晨 刘磊鑫 WANG Mengnan;LI Jianghai;LIU Chen;LIU Leixin(School of Earth and Space Sciences,Peking University,Beijing 100871)

机构地区：[1]北京大学地球与空间科学学院,北京100871

出　　处：《高校地质学报》2023年第2期251-260,共10页Geological Journal of China Universities

基　　金：大西洋两岸被动陆缘盆地油气勘探开发与关键技术(2016ZX05033001)资助。

摘　　要：贝加尔裂谷位于全球最大的大陆板块中心,远离任何活跃板块边界,却是地球上现今构造活动最为活跃和复杂的地区之一,其形成演化的主控因素是地球科学界广泛讨论的问题之一并一直存在争议。文章通过物理实验模拟手段,研究了裂谷区在局部拉张背景下,岩石圈形变过程。贝加尔裂谷区位于较强的西伯利亚克拉通与较弱的萨彦—贝加尔造山带结合部位。克拉通一侧下地壳强度大,壳幔机械耦合程度高,实验结果显示,当区域遭受局部拉张时,应力易在克拉通一侧聚集,最先于克拉通与造山带薄弱缝合处的靠近克拉通边缘一侧发育深大断裂。随着岩石圈不断伸展,应力向造山带一侧传递,断裂也随之向造山带一侧发生迁移,呈现雁列式排列。古老克拉通相比于年轻造山带下地壳流变性质差异,决定了贝加尔裂谷窄且深凹陷的发育特征及发育结构的不对称性。Baikal Rift is located in the center of the largest continental area in the world,far away from any active plate boundary,but it is one of the most active and complex tectonic areas on earth today.The main controlling factors of its formation and evolution have been widely discussed.Yet,it is still the subject of intense debate concerning.In this paper,the process of lithospheric deformation under the background of local tension is studied by means of physical modeling.Baikal rift is located at the joint of the strong Siberian craton and the weak Sayan-Baikal fold belt.The Siberian craton is characterized by a strong lithosphere where the crust and mantle are mechanically coupled.The experimental results show that stress tends to accumulate on the craton side under the regional tension,and a deep and large fault first developed near the edge of the craton at the weak suture between the craton and orogenic belt.With the continuous extension of the lithosphere,the stress is transferred to the side of the orogenic belt,and the faults also migrate to the side of the orogenic belt,presenting an echelon arrangement.Compared with the young fold belt,the old craton has a cold and hard rigid basement,which determines the narrow and deep depression characteristics of Baikal rift and the asymmetry of its structure.

关 键 词：贝加尔裂谷 构造发育 岩石圈流变学 物理模拟 

分 类 号：P548[天文地球—构造地质学]