A Broadband Seismic Network in the Middle-Lower Yangtze Metallogenic Belt, China

Abstract

The middle–lower Yangtze Metallogenic belt (MLYMB) is surrounded by the North China Block in the northwest, the Dabie Orogen in the west, and the Yangtze Block in the south (Fig. 1a). The MLYMB experienced tectonic adjustment from south–north compression in the late Jurassic period to extension in the Cretaceous period (Ren et al. , 1997), as indicated by the extensive Cretaceous calc‐alkaline to alkaline volcanism, granitoid magmatism, and synchronously rift volcanic basins. Major geologic features observed today, including the extensional tectonic settings in eastern China and the MLYMB, were basically formed in this transitional period. Figure 1. (a) Schematic map of the tectonic background in the middle–lower Yangtze Metallogenic belt (MLYMB) (study region). The blue patches are the known metallogenic regions. NZ, Ningzhen; NW, Ningwu; LZ, Luzong; TL, Tongling; AQ, Anqing; GC, Guichi; JR, Jiurui; EDN, Edongnan; XGF, Xiangfan‐Guangji fault; YCF, Yangxin‐Changzhou fault; and TLF, Tancheng‐Lujiang fault. The triangles denote the permanent stations deployed by China Digital Seismological Network. (b) Installation of the sensor. A flat marble board is fixed horizontally at the bottom of an excavation (the depth of the excavation is about 100 cm) using fast concrete mix. The sensor is then placed on this marble inside this excavation, with its horizontal components oriented north–south. The excavation is protected by a large, 50 cm×50 cm box without a base panel, which allows the closing of the geophone space and is used to thermally isolate the sensor. Seven large ore‐concentration districts with more than 200 kinds of polymetallic (Cu, Au, Mo, and so on) deposits are clustered in the narrow mineralization zone of the MLYMB. It is still unclear how such rich mineral resources are concentrated in such a narrow zone and what deep geodynamic processes and magmatic activities are …