鄂尔多斯东北缘大同盆地新生代构造演化
发布时间：2018-08-30 15:41
【摘要】：大同盆地位于华北克拉通中部,自晚中新世以来经历了持续强烈的伸展作用。本文从地构造应力场、玄武岩演化两个方面对大同盆地新生代浅部伸展和与深部作用进行分析。在构造应力场方面,根据边界断裂的擦痕数据,反演控制大同盆地形成的构造应力场是：σ1垂直,σ2、σ3水平,σ2的方位角为60°,σ3方位角为150°,为NW向伸展的正断型构造应力场,不同于华北东部NE向挤压的走滑型构造应力场。对盆地内新生代玄武岩的研究表明,大同地区碱性玄武岩所占的比例随着时间不断下降,大同盆地内部碱性玄武岩Yb含量不断上升,暗示了岩石圈的不断减薄。本文首次获得大峪口玄武岩K-Ar年龄为0.68±0.13Ma。分析认为,浅部构造应力场的形成与深部地幔活动相一致,大同与华北东部构造应力场的差异性对应岩石圈厚度变化的差异性。据此,本文提出了大同盆地的形成演化模式：在晚中生代以来的华北岩石圈减薄基础上,10-8 Ma以来,软流圈上涌,地幔活动将热量传递给地壳,造成脆性上地壳出现一定强度的NW向伸展构造应力场,控制了大同裂谷型盆地形成演化。此过程可能受到了青藏高原东向挤出和太平洋西向俯冲的联合影响。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了新的依据。
[Abstract]:Datong Basin is located in the central part of North China Craton and has undergone intensive extensional process since Late Miocene. This paper analyzes the shallow extension and deep action of Datong Basin in Cenozoic from two aspects of tectonic stress field and basalt evolution. The tectonic stress field formed in the basin is_1 vertical, _2, _3 horizontal, _2 azimuth is 60 degrees, _3 azimuth is 150 degrees. It is a NW extensional normal tectonic stress field, which is different from the NE compressional strike-slip tectonic stress field in eastern North China. The K-Ar age of the Dayukou basalt is 0.68+0.13 Ma for the first time. The analysis shows that the formation of the shallow tectonic stress field is consistent with the deep mantle activity, and the difference between the Datong and the eastern North China tectonic stress field is opposite. According to the difference of lithospheric thickness, this paper puts forward the formation and evolution model of Datong basin: on the basis of lithospheric thinning in North China since Late Mesozoic, asthenosphere has been upwelling since 10-8 Ma, and mantle activity has transferred heat to the crust, resulting in a certain intensity of NW-trending extensional tectonic stress field in the brittle upper crust. The formation and evolution of the syn-rift basin may be influenced by the East extrusion of the Qinghai-Tibet Plateau and the West subduction of the Pacific Ocean.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P542
[Abstract]:Datong Basin is located in the central part of North China Craton and has undergone intensive extensional process since Late Miocene. This paper analyzes the shallow extension and deep action of Datong Basin in Cenozoic from two aspects of tectonic stress field and basalt evolution. The tectonic stress field formed in the basin is_1 vertical, _2, _3 horizontal, _2 azimuth is 60 degrees, _3 azimuth is 150 degrees. It is a NW extensional normal tectonic stress field, which is different from the NE compressional strike-slip tectonic stress field in eastern North China. The K-Ar age of the Dayukou basalt is 0.68+0.13 Ma for the first time. The analysis shows that the formation of the shallow tectonic stress field is consistent with the deep mantle activity, and the difference between the Datong and the eastern North China tectonic stress field is opposite. According to the difference of lithospheric thickness, this paper puts forward the formation and evolution model of Datong basin: on the basis of lithospheric thinning in North China since Late Mesozoic, asthenosphere has been upwelling since 10-8 Ma, and mantle activity has transferred heat to the crust, resulting in a certain intensity of NW-trending extensional tectonic stress field in the brittle upper crust. The formation and evolution of the syn-rift basin may be influenced by the East extrusion of the Qinghai-Tibet Plateau and the West subduction of the Pacific Ocean.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P542
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