大同盆地形成机制的构造研究  

Structural Analysis on the Formation Mechanism of Datong Basin

作　　者：岑敏[1,2] 董树文[2,1] 施炜[3] 周涛发[1] 陈龙[3,4] 陈兴强[2] 

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009 [2]中国地质科学院,北京100037 [3]中国地质科学院地质力学研究所,北京100081 [4]中南大学地球科学与信息物理学院,长沙410083

出　　处：《地质论评》2015年第6期1235-1247,共13页Geological Review

基　　金：中国地质调查局地质调查项目(编号1212011220259;1212011120099)的成果

摘　　要：大同盆地为位于华北地块中部的新生代断陷盆地,自中新世晚期以来经历了持续的强烈伸展作用。基于边界断裂滑动的运动学及动力学分析,结合对本区新生界沉积地层与玄武岩资料的总结归纳以及对区域动力学背景的讨论,本文提出了大同盆地的形成机制:自10~8 Ma以来,鄂尔多斯地块东北缘形成NW向伸展的构造应力场,其中σ1垂直,σ2、σ3水平,σ2的方位角为60°,σ3方位角为150°,此构造应力场控制边界断裂的运动,形成NE向大同断陷盆地。盆地的形成对应岩石圈减薄深部过程,可能受到了印度——欧亚板块碰撞、太平洋——欧亚板块碰撞板缘动力作用的影响。本文将岩石圈浅部构造应力场与深部地幔活动结合起来综合分析大同盆地的形成机制,并提出了一些新的认识:控制大同盆地形成的正断型构造应力场不同于华北区域性走滑型构造应力场;首次测得了与地幔活动相关的大同火山群大峪口玄武岩K-Ar年龄为0.68±0.13Ma;大同盆地具有板内狭窄型裂谷的构造特征。本文为建立鄂尔多斯地块东缘山西地堑系的运动学和动力学模型提供新的依据。The Datong basin is a Cenozoic rift located in the central part of North China Craton. It has experienced intensive and persistent rifting since late Miocene. Based on the analysis on the kinematics and dynamics of the marginal faults,the summary on the Cenozoic sedimentary and basaltic strata and the discussion on regional dynamic background,writers proposed the formation mechanism of the Datong basin. Since 10 ~ 8 Ma,the NW extending tectonic stress field formed on the northeastern margin of the Ordos block and acted on the marginal faults resulting in the Datong basin's forming. The formation of the Datong basin corresponds to the lithosphere thinning process and may be related to the far-field effect of India——Eurasia collision and Pacific——Eurasia collision. What's more,the article shows some new facts. The normal fault stress field of the Datong basin is thatσ1is vertical,σ2and σ3is horizontal,the strike of σ3is about 150°,which differs from the strike-slip fault stress field of North China. The K-Ar age of Dayukou basalt in Datong volcanic field related to mantle activity is 0. 68 ±0. 13 Ma. The Datong basin has characteristics of intraplate narrow rifts. All these research provide a new basis for building the Cenozoic kinematics and dynamatics model of the Shanxi Rift system.

关 键 词：大同盆地 形成机制 断层滑动矢量测量 构造应力场 地幔活动 板内裂谷 

分 类 号：P548[天文地球—构造地质学]