摘要
海拉尔盆地是叠置于内蒙古—大兴安岭古生代碰撞造山带之上的中—新生代盆地,总体上呈北东向展布,由三坳、两隆五个一级构造单元组成,自西向东依次为扎贲诺尔坳陷、嵯岗隆起、贝尔湖坳陷、巴彦山隆起和呼和湖坳陷,其中乌尔逊凹陷、贝尔凹陷是位于贝尔湖坳陷凹陷南部的两个二级构造单元。研究表明,乌尔逊—贝尔凹陷在早白垩世大磨拐河期—伊敏期早期、伊敏期末期分别经历了北西-南东向、近东西向两次较长时间的挤压作用,使伸展断陷中的部分控陷正断层发生反转作用,在研究区形成了新的断层传播褶皱、断层转折褶皱以及叠瓦构造和双重构造、突发构造、构造三角带等。由于挤压构造的几何学、运动学特征的不同及隆升速率与同构造生长地层沉积速率的比值在空间上的差异,同挤压地层层序在不同构造部位也表现出不同的沉积特点,其构造特征与造山带十分相似。乌尔逊—贝尔凹陷中两次挤压构造的发现,说明中国东北地区的地壳厚度在早白垩世并非一直处于伸展减薄状态,而是在上述两次挤压时期地壳处于叠置增厚的特点,在空间上形成挤压坳陷型盆地和陆内(板内)造山带相间分布的构造格局。
Hailar Basin is a Meso-Cenozoic basin which superimposed on the Paleozoic collision orogenic belt of Inner Mongolia-Greater Hinggan Mountain. The basin, trending north-east, consists of five first-order structural units (three depressions and two uplifts), they are, from west to east, the Zhalenuoer Depression, Cuogang Uplift, Beier Lake Depression, Bayanshan Uplift and Huhe Lake Depression, respectively. Wuerxun and Beier Sags are two second-order structural units in the south of Beier Lake Depression. The research indicates that in the Early Cretaceous, Wuerxun-Beier Sag underwent two long-term compressions: NW-SE tren ding during Damoguaihe Period to early Yimin Period, and near EW trending during late Yimin Period, respectively. The compressions led to the inversion of some depression-controlled normal faults in the extensional faulted depression, and formed new fault-propagation fold, fault-band fold, imbricate structure, duplex structure, pop-up structure, triangular zone etc. Because of the differences in geometric and kinematic features and the variance in the ratio of the uplift rate of compressional structures to the deposition rate of isostructurally growing strata in space, the syn-coltision strata sequences show different sedimentary features in different structural positions. These structural features are very similar to those of orogenic belt. The discovery of two phases of compressional structure in Wuerxun-Beier Sag proved that the crust of Northeast China was not always in the state of extension and thinning in the Early Cretaceous, but showed the features of superimposition and thickening during the two compression periods, and thus formed structural framework of alternative distribution of compression-depression basins and intracontinental (intraplate) orogenic belt in space.
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2009年第4期138-146,共9页
Earth Science Frontiers
基金
国家自然科学基金项目(40772125)
大庆油田有限责任公司勘探开发研究院项目(12010022002100277)
关键词
挤压构造
构造特征
断层相关褶皱
生长地层
早白垩世
地质意义
乌尔逊-贝尔凹陷
海拉尔盆地
compressional structure
structural feature
fault-related fold
growing strata
Early Cretaceous
geological significance
Wuerxun-Beier Sag
Hailar Basin