燕山构造带承德地区晚侏罗世盆地火山-沉积地层充填过程和构造演化

    Late Jurassic volcano-sedimentary sequences, filling process and evolution of basins in the Chengde area, Yanshan tectonic belt, China

    • 摘要: 燕山地区上侏罗统主要包括髫髻山组和土域子组2套地层。根据这2个组中火山岩同位素年龄的数据,认为这2个组的主体应是同期形成的,而非简单的上、下层关系。通过岩相、相组合、古流向和物源分析,对承德地区晚侏罗世的沉积环境进行了恢复,认为盆地发育的早期沉积物虽主要来自于北部,但并非受控于北部向南的逆冲推覆构造带。尚义-平泉断裂带具有明显的走滑特征,并控制了当时的火山喷发。提出了一个新的盆地演化模型,能很好地解释承德地区晚侏罗世火山-沉积地层的发育、古流向、物源区的变化和盆地的构造-沉积过程。

       

      Abstract: The Upper Jurassic in the Yanshan belt consists of the Tiaojishan and Tuchengzi formations. Analysis of the radiometric age data of the volcanic rocks indicates that the main parts of the two formations formed synchronously, rather than show a simple overlapping stratigraphic relation. Based on an analysis of the lithofacies, facies association, direction of paleocurrents and provenance, the Late Jurassic sedimentary environment in the Chengde area has been reconstructed, and it is thought that the sediments in the basins in the early stage of its development mainly came from north of the basin. However, even so, the authors do not think that the basin development was controlled by a south-vergent thrust fault in the north. The Sbangyi-Pingquan fault has pronounced strike-sfip features and controlled volcanic eruption. The paper proposes a new model for the basin evolution in the Chengde area, which may well explain the development of volcano-sedimentary sequences, changes in direction of paleocurrents and provenance and tectonic-sedimentary process of basins in the Chengde area.

       

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