New data on the evolution of the Tan–Lu fault belt: constraints from geological–geophysical surveys in the southern segment
New data on the evolution of the Tan–Lu fault belt: constraints from geological–geophysical surveys in the southern segment
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DOI：
10.1080/00206814.2011.649950
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发表时间：
2012-08
影响因子：
2.6
通讯作者：
Jiaodong Zhang;Xiaoyong Yang;Wei-dong Sun;Guangtao Wang;Changchun Yang;Chengzhai Liu;Deliang Liu
中科院分区：
文献类型：
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作者：
Jiaodong Zhang;Xiaoyong Yang;Wei-dong Sun;Guangtao Wang;Changchun Yang;Chengzhai Liu;Deliang Liu
郯庐断裂是我国东部著名的活动断裂带，40多年来一直是地质研究的热点。自20世纪90年代末以来，中国石油公司和大学对该位错带进行了大量的地球物理和地质调查。但其深部构造、活动期次、断裂机制等问题仍不清楚。本研究以郯庐断裂带夹山-庐江段深部构造为研究对象，采用高精度大地电磁测深、磁测深等地球物理手段，结合人工地震主动震源法进行了研究。我们的研究结果表明，这一段是由几个子断层。郯庐断裂带南段沿着夹山-庐江次级断裂，根据地质特征的对比，可分为两部分。以池河-太湖次级断裂为界，研究了两条断裂的构造演化特征。在池河-太湖次级断裂以东地区，沿着多条次级断裂走滑活动为主。仅夹山-庐江次级断裂出露地表，形成一个大型正花状构造，是中侏罗世晚期至晚侏罗世早期沿位错带沿着走滑运动的结果。定远县境内存在三条次级断裂，其中两条在合肥盆地南部消失。只有池河-太湖次级断裂延伸到盆地的东缘，形成了早白垩世形成的半地堑式凹陷。结果表明，郯庐断裂带南段现今深部构造是走滑构造和伸展构造共同作用的结果。
The Tan–Lu fault is a well-known active fault belt in eastern China that has been the focus of geologic studies over the past 40 years. Since the late 1990s, numerous geophysical and geological investigations of this dislocation zone have been carried out by Chinese oil companies, as well as by universities. However, its deep structure, active periods of slip, and fault mechanism remain obscure. This study focuses on the deep structures within the Jiashan–Lujiang segment of the Tan–Lu fault belt, using high-precision geophysical tools, including magnetotelluric and magnetic sounding, and artificial seismic exploration using active source methods. Our results suggest that this segment is composed of several sub-faults. The southern part of the Tan–Lu fault belt, along the Jiashan–Lujiang sub-fault, can be divided into two parts on the basis of contrasting geological features. The Chihe–Taihu sub-fault is taken as the boundary between the two. The region east of the Chihe–Taihu sub-fault is dominated by strike–slip activity along several sub-faults. Only the Jiashan–Lujiang sub-fault is exposed at the surface, forming a large, positive flower structure, the result of late Middle Jurassic to early Late Jurassic strike–slip movement along the dislocation zone. Three sub-faults are present in Dingyuan County, two of which disappear in the southern Hefei Basin. Only the Chihe–Taihu sub-fault extends to the eastern edge of this basin, creating a half-graben depression that formed during the Early Cretaceous. Our results indicate that the present-day deep structure of the southern portion of the Tan–Lu fault zone is the result of a combination of strike–slip and extensional tectonics.