Multiscale 3-D imaging of the crustal electrical structure beneath the Caosiyao porphyry Mo deposit, North China

作者：Liuyang Xu, Sheng Jin, Yaotian Yin, Wenbo Wei, Gaofeng Ye, Hao Dong, Letian Zhang, Jianen Jing, Chengliang Xie · 发表于：Geophysical Journal International · 年份：2022 · DOI：10.1093/gji/ggac244 · 被引用次数：10 · 研究领域：Geophysical and Geoelectrical Methods、Seismic Waves and Analysis、Geophysical Methods and Applications

SUMMARY We proposed a stepwise procedure to obtain a multiscale 3-D resistivity model beneath the Caosiyao porphyry Mo deposit. Due to the joint inversion of data collected from 302 audio-frequency magnetotelluric and 33 broad-band magnetotelluric sites, this model can simultaneously combine both the shallow resolution and detection depth. The near-surface part of the model reveals the high-resolution structures. Specifically, a high-resistivity body (>500 Ω m) is interpreted as the late Jurassic porphyry intruding into the metamorphic basement. Two NE-trending high-conductivity (<100 Ω m) belts are interpreted as fault zones. The one in the southeast extends deeply (>15 km) is suggested to be a crust-scale weak zone and conduit for transporting ore-forming magmas and fluids. The other one is shallow (<2 km), but coincides with outcropped orebodies and alteration zones, so it may have played an important role in the hydrothermal alteration and mineralization. A predominant high-conductivity block (<30 Ω m) occurs within the lower part (∼15–30 km) of the model and connects with Caosiyao deposit through the inferred crust-scale fault. Its enhanced conductivity may result from the abundant fluids. We determined it had been a mid-lower crustal magma chamber providing space for the mixing of ore-forming magmas and fluids, as well as the element exchange during the mineralization. Combined with a previous magnetotelluric imaging, we suggested the ...