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Title:: High-density Resistivity Surveying and the Features of Boundary Fault along the Edge of Anyuan Basin

Author(s):: WANG Ai-guo¹; 2; YANG Bin¹; ZHOU Jun-xi¹; (1. Lanzhou Base of Institute of Earthquake Prediction, CEA, Lanzhou 730000, Gansu, China)(2. Earthquake Administration of Gansu Province, Lanzhou 730000, Gansu, China)

Keywords:: Anyuan Basin; high-density resistivity tomography; Maomaoshan Mountain fault; Jinqianghe River-Maomaoshan fault; Gansu

摘要:: 结合钻孔资料,采用高密度电法对安远盆地边缘的毛毛山南麓活动断层(F₁)和金强河—毛毛山北麓活动断裂(F₃)进行了探测。结果表明,F₁断层错断了盆地区内晚更新世晚期至全新世早期的Ⅲ级阶地; 受拉分构造的影响,该断层最新活动显示了向安远拉分盆地方向迁移的阶梯状递减的张性正断裂性质。F₃断层在走向上呈锯齿状,错断了山前Ⅰ级冲洪积阶地及全新统至上更新统地层,断距大,基岩破碎带宽,新活动主要表现为断层附近原地连续沉降。这两条断层的发育特征及展布位置的确定,为该区工程稳定性评价及建设提供了依据。

Abstract:: The south foot fault of Maomaoshan Mountain(F₁)and the north foot fault of Jinqianghe River-Maomao-shan Mountain(F₃)develop along the edge of Anyuan Basin. We conducted high-density resistivity surveying combining with boring data across F₁ and F₃. The results show that F₁ cut the 3rd terrace which formed in late Pleistocene, and the last activity was extensional normal slip by echelonment falling down toward the basin. F₃ stroke zigzag and cut the 1st alluvial-proluvial terrace and Holocene stratum with large displacement of fault and wide fracture zone in bedrock, and the last activity is the continuous falling around the fault. The survey confirms the characteristics and locations of the faults along the basin edge, which provides the evidence for engineering stability evaluation and construction.