郯庐断裂带泗县徐井段晚第四纪新活动的宏微观现象初步研究

发布时间：2018-06-13 22:49

  本文选题：郯庐带 + 晚第四纪　； 参考：《大地测量与地球动力学》2017年12期

【摘要】：探槽揭示,郯庐断裂带安徽泗县徐井一带第四纪以来的新活动表现为逆断型崩积楔、张裂楔、碎裂流和地震断层。根据现场分析初步认为,中更新统沉积后,探槽所在部位先遭受挤压,晚白垩世砖红色砂岩自西向东上冲垮塌到中更新世沉积之上,形成逆断型崩积楔-1;接着发生张性断裂活动,形成开口向上的张裂楔;随后,所在部位又遭受挤压,沿张裂楔的东边界断面挤压逆冲活动产生碎屑物质上抛流动,形成逆断型崩积楔-2;其上逐步形成更新沉积,当黑土层堆积以后,再次遭受挤压,使得断面上下黑土层堆积厚度显现差异。这表明中更新统沉积以后,断裂曾先后发生挤压-引张-挤压-挤压共4次活动,最新活动在全新世早期。根据逆断型崩积楔、张裂楔和地震断层等的成因,这几次活动应属高速粘滑活动,对应几次强烈的史前地震活动事件。上述认识部分得到原态微观观测分析结果的证实。
[Abstract]:The trench reveals that the new activities since Quaternary in the area of Xujing, Sixian, Anhui Province, the Tanlu fault zone are characterized by reverse fault-type avalanche wedge, extensional wedge, cataclastic flow and seismic fault. Based on the field analysis, it is concluded that after the Middle Pleistocene deposits, the location of the grooves was first squeezed, and the late Cretaceous brick red sandstone collapsed from west to east to the middle Pleistocene deposits. Forming an inverse faulted accretion wedge-1, followed by tensional fracture activity, forming an upward opening fracture wedge, and then the location is squeezed again, and the thrusting activity along the eastern boundary of the tensional wedge results in the upcast flow of debris material, which is caused by the thrusting activity along the eastern boundary of the detritus wedge. The formation of an inverse fault-type caving wedge -2, on which the renewal deposits are gradually formed, and when the black soil layer is accumulated, it is again squeezed, which makes the thickness of the upper and lower black soil layers appear to be different from that of the upper and lower sections. This indicates that the faults had four compression-extension-compression events after the Middle Pleistocene deposition, the latest activity occurred in the early Holocene. According to the origin of inverse fault type accretion wedge, tension wedge and seismic fault, these events should belong to high speed visco-slip activity, corresponding to several strong events of prehistoric seismicity. The above understanding is confirmed by the results of microscopic observation in the original state.
【作者单位】： 安徽省地震局;安徽蒙城地球物理国家野外科学观测研究站;
【基金】：安徽省公益性地质项目(2015-g-25)~~
【分类号】：P315.2
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本文编号：2015803