舒兰盆地构造格架的地球物理制约

    Structural characteristics and evolution of the Shulan Basin

    • 摘要: 舒兰盆地位于佳伊地堑中南段,伊通盆地东北部,是北东向展布的一个狭长状断陷盆地,前人仅对舒兰盆地开展过初步的地质调查,但对盆地构造特征、演化过程的研究相对薄弱。综合区域地质资料、孢粉资料等,分析对比了舒兰盆地与伊通盆地的新生代沉积地层;通过电法、地震剖面解析,认为盆地南段为半地堑式构造特征,中段为地堑式构造特征,盆地北段从西北至东南呈阶梯状加深的构造形态;结合钻井资料分析认为,盆地基底岩性南段以上二叠统杨家沟组为主,中段主要由花岗岩和白垩系组成,北段主要由白垩系组成;综合分析认为,舒兰盆地构造演化可划分为3个构造演化阶段,即初始断陷期(古新世早期)、断陷期(古新世—渐新世)和挤压反转期(渐新世—中新世)。

       

      Abstract: Located in the middle south segment of the Jia-Yi graben and northeast Yitong Basin, the Shulan Basin is a NE-trending narrow faulted basin. Previous studies only carried out preliminary geological survey in the Shulan Basin, whereas researches on the structural characteristics and evolution of the basin were insufficient. This paper focused on the correlations of Cenozoic strata between the Shulan Basin and Yitong Basin on the basis of all research data collected, e.g., sporopollens and stratigraphy. Moreover, the electrical and seismic profiles from the Shulan Basin suggest that the southern section of the basin shows half-graben type structure, the middle basin shows graben type structure, and the northern section becomes increasingly deep step by step southwestward. In addition, the basement of the basin is slightly different in different parts and characterized by upper Permian Yangjiagou Formation, Cretaceous granites and Cretaceous strata in the southern, middle and northern parts, respectively. A comprehensive analysis suggests that the Shulan Basin underwent three tectonic evolutional stages, e.g., the initial faulted phase (Early Paleocene), the main faulted phase (Paleocene-Oligocene), and the extrusion-reversion phase (Oligocene-Miocene).

       

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