基于遥感和重力多源数据研究沂沭断裂带南段及周边断裂的交切关系

Intersection relationship between south segment of Yishu fault zone and surrounding faults derived from remote sensing and gravity multi-source data

  • 摘要: 以沂沭断裂带南段(沂水县—郯城县)及周边地区为研究对象,收集该地区的遥感影像、数字高程模型和布格重力数据,研究区域构造地貌和地壳深部构造特征,进一步对沂沭断裂带南段与周边断裂的交切关系予以分析.研究结果显示:在遥感影像中,蒙山山前断裂和苍尼断裂的构造地貌特征明显,断裂沿线发育水系转弯、河流错断、断层陡坎、断层崖、断层三角面等地貌现象,反映了两断裂正断兼左旋走滑的活动性质,其中蒙山山前断裂向东延伸至莒南县附近,苍尼断裂向东延至郯城一带,两条断裂在地貌上均截切了沂沭断裂带;在重力细节场中,两断裂形成了不同尺度上的重力梯度带,切割至下地壳深度,在地壳浅层至深层均交切于沂沭断裂带,且交切处出现扭曲、断折、串珠状等重力异常现象,证实其在地壳深部切穿沂沭断裂带.因此,两条断裂的遥感和重力场解译结果具有明显的一致性,在地貌及深部均截切沂沭断裂带南段,使其出现分段性特征.此外,在临沭县附近发现了一条新断裂,即相庄—沙岭断裂,该断裂在地貌上呈北高南低,沿线水系发生左旋同步转弯,且在1—3阶重力细节场中形成线性梯度条带,故推测该断裂下切至中地壳深度,在临沭县附近截切沂沭断裂带交切于东地堑,并未延伸至西地堑.

     

    Abstract: This paper collected remote sensing image, digital elevation model and Bouguer gravity data of the south segment of Yishu fault zone (namely the segment between Yishui county and Tancheng county) and its surrounding areas, and studied the regional tectonic landform and deep crustal structural characteristics so as to analyze the intersection relationships between south segment of Yishu fault zone and its surrounding faults. The research results indicate that Mengshan piedmont fault and Cangni fault exhibit obvious tectonic characteristics consisting of river bends, fault steep, gully leaps, fault scarps and fault facets in the remote sensing images. In detail, Mengshan piedmont fault extends eastward to Ju'nan county, while Cangni fault extends eastward to Tancheng. Both the faults crosscut Yishu fault zone on the geomorphology; in the gravity detail field, the two faults form a gravitational gradient zone on different scales, which extend down to the lower crust and appear as deep faults. Moreover, the lineaments intersect with Yishu fault zone and contribute to the distorted, broken, beaded gravity anomalies, confirming that Yishu fault zone has been cut through in the deep crust. Therefore, a great uniformity between the interpretation results of two faults in remote sensing and gravity field suggests that the two faults all crosscut south segment of Yishu fault zone in landform and deep crust, so that the segmentation characteristics occur. In addition, there is a new fault developed near Linshu county, namely Xiangzhuang-Shaling fault. The fault is higher in north and lower in south, along which the rivers left-hand bend synchronously, and in the 1-to-3-order gravity field there are linear gradient zones, so it is speculated that the fault extends down to the middle crust, and crosscuts the eastern graben of Yishu fault zone near Linshu county, but not extends to the western graben.

     

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