Crustal Electrical Structure of the Wuwei Basin, Lower Yangtze Region of China, and Its Geological Implications

Abstract

The Wuwei Basin is one of the most important oil- and gas-bearing basins in the Meso-Cenozoic basin groups in the Lower Yangtze River region. It has great shale gas resource prospects. The formation mechanism of this basin is poorly studied for lack of constraining data for deep structures. In this paper, a crustal electrical structure model of the Wuwei Basin and the adjacent areas is constructed based on the two-dimensional inversion of a magnetotelluric (MT) sounding profile achieved with the nonlinear conjugate gradient method. The results show that large-scale low-resistance bodies have developed in the underlying middle and lower crust of the Wuwei Basin, and are different from the uplifts on the two sides according to their high-resistance electrical characteristics. The electrical structure and regional geological and geophysical data suggest that the peak zone of the Chuzhou-Chaohu foreland fold-and-thrust belt is located on the east bank of the Yangtze River (Wuhu Section), which, together with the main thrust fault belt in the east, forms a typical thrust structure belt. An early Yanshanian sinistral strike-slip fault developed in the deep part of the Wuwei Basin, which may have controlled the formation and evolution of the basin, whereas the tectonic inversion of the early-developed thrust faults is relatively weak. These findings provide a geophysical basis for future studies of basin tectonic evolution and regional tectonic frameworks.

Keywords

Wuwei Basin / Lower Yangtze / deep structure / electrical structure / fold-and-thrust belt / shale gas / magnetotellurics / geophysics

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