Integrated geophysical exploration and prospecting model for loess-covered gold deposits: A case study of the southern Yixingzhai Gold Deposit, Shanxi Province

Abstract

The Yixingzhai Gold Deposit in Shanxi Province is a major gold-polymetallic deposit in northeastern Shanxi, and its southern Sunzhuang area is covered by a thick loess layer, rendering conventional geological prospecting extremely challenging. To achieve a breakthrough in deep prospecting, this study developed a suite of integrated geophysical exploration techniques based on regional geological conditions and the petrophysical properties of local rocks and ores. Time-domain induced polarization (TDIP) surveys with large electrode spacing (AB = 2,000 m), long power supply duration (8 s), and high current intensity (>10 A) were carried out, and combined with high-precision ground magnetic surveys, to interpret the subsurface geological structures, spatial distribution of concealed rock masses, and mineralization information beneath the loess overburden. The results show that integrated geophysical anomalies clearly reveal the distribution characteristics of NW- and SN-trending fault systems and their controlling effects on metallogenesis, and three concealed intermediate-acidic rock masses (diorite, granitic porphyry, quartz porphyry) closely associated with mineralization are accurately delineated. By adopting the multi-information coupling method of “IP anomalies – metal factor – geochemical anomalies”, ore-induced anomalies are effectively distinguished from non-ore interference. Drill verification confirms the exposure of gold-copper ore (mineralized) bodies with a cumulative thickness of over 22 m in the study area, with a maximum gold grade of 1.22 g/t. A comprehensive information prospecting model for loess-covered areas is established in this study, which offers a valuable reference for deep prospecting in similar covered regions.