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Aseismic slip on the active Sabz-Pushan and Sepidar thrusts, Iran: microstructural and kinematics evidence of the slickenline fibre creep
International Journal of Earth Sciences ( IF 1.8 ) Pub Date : 2021-07-26 , DOI: 10.1007/s00531-021-02081-1
Khalil Sarkarinejad 1 , Maryam Mottahedi 1 , Maryam Nori 1
Affiliation  

For decades, seismogenic faults of the Zagros orogen that episodically experienced large earthquakes studies in detail; however, the active faults with the aseismic slips have only have been studied as a possible contributor to their seismic hazard assessments. This study identifies the contribution of pressure solution creeps to their seismic hazard assessments. Microscopic measurements of the calcite slickenline fibres on the Sabz-Pushan thrust planes documents a length of 1.28 ± 0.50 mm. Microscopic-scaled stretched calcite length measurements represent the present slip magnitude along with this thrust. This slip magnitude correlates with GPS velocity measurements of the Sabz-Pushan thrust of 1.5 ± 0.2 mm/year. The slip magnitude of the aseismic creep in the Sabz-Pushan thrust is closely associated with postseismic adjustments of the 1824 and 1994 earthquakes. The dynamic fluid flow and fluid circulations of the Mand (Qara Aghj) River along with the Sabz-Pushan and Sepidar thrusts and sub-simple shearing are the main controlling factors in an aseismic slip of the Sabz-Pushan and Sepidar thrusts. These thrusts forming a compressional push-up structure that may be a critical factor in the brittle deformation of the damage zone and ductile flow in-depth on the fault planes. The presence of rotated lens-shaped Type III e-twins within the slickenline fibres on the thrust planes confirms that the depth of aseismic creep occurred at > 400 °C which represents calcite ductile flow of the pressure solution mechanism as a potentially important deformation along with the Zagros thrust system of the Zagros orogen. Analysis of the slickenline fibre orientations indicates that the mean plunge and trend of maximum principal stress (σ1) of the Sabz-Pushan thrust are N31° E–N36° E, sub-horizontal and the mean trend of the minimum principal stress (σ3) is NNW and is sub-vertical. Horizontal maximum principal stress confirms that the Sabz-Pushan characterizes as a dip-slip fault.



中文翻译:

伊朗 Sabz-Pushan 和 Sepidar 逆冲断层上的地震滑动:光滑线纤维蠕变的微观结构和运动学证据

几十年来,扎格罗斯造山带的发震断层偶尔经历了大地震的详细研究;然而,具有抗震滑动的活动断层仅被研究作为其地震危险性评估的可能因素。这项研究确定了压力溶液蠕变对其地震危险性评估的贡献。Sabz-Pushan 推力平面上方解石滑线纤维的显微测量记录长度为 1.28 ± 0.50 毫米。微观尺度的拉伸方解石长度测量值代表了当前的滑动幅度以及这种推力。这种滑动幅度与 Sabz-Pushan 推力的 GPS 速度测量值 1.5 ± 0.2 毫米/年相关。Sabz-Pushan 冲断层地震蠕变的滑动幅度与 1824 年和 1994 年地震的震后调整密切相关。Mand(Qara Aghj)河的动力流体流动和流体循环以及Sabz-Pushan和Sepidar逆冲断层和亚简单剪切是Sabz-Pushan和Sepidar逆冲断层地震滑动的主要控制因素。这些推力形成了一个压缩的上推结构,这可能是破坏区脆性变形和断层面上深入延性流动的关键因素。在推力平面上的光滑线纤维中存在旋转的透镜状 III 型 e-孪晶证实了抗震蠕变的深度发生在 > 400 °C 代表压溶机制的方解石延展性流动,作为潜在的重要变形以及扎格罗斯造山带的扎格罗斯推力系统。对光滑线纤维取向的分析表明,最大主应力的平均下降和趋势(Sabz-Pushan 逆冲推力的σ 1 ) 为 N31° E–N36° E,次水平,最小主应力 ( σ 3 )的平均趋势为 NNW 且接近垂直。水平最大主应力证实了Sabz-Pushan 断层具有倾滑断层的特征。

更新日期:2021-07-26
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