复电阻率法在滇东北羊场隐伏磷矿深部勘查中的应用研究OA

Phosphate rock is a national strategic mineral resource.With the gradual depletion of easily discovered deposits,the exploration and prospecting for concealed phosphate deposits have become a focus.The Yangchang phosphate deposit in northeastern Yunnan is a newly discovered super-large concealed deposit.However,its thick overburden and deep burial depth render conventional geological and geochemical methods ineffective for detection.Addressing this challenge,this paper presents the first application of the complex resistivity(CR)method for deep exploration in the Yangchang phosphate deposit,which aims to investigate the effectiveness of this method in locating and predicting concealed phosphate ore bodies.A north-south trending CR profile,5.28 km in length,was deployed in the study area.Data were acquired using the V8 multi-function electrical system and subsequently inverted using the SFIPX-SW system combined with the Cole-Cole model,which effectively separated the induced polarization(IP)effect from the electromagnetic(EM)coupling effect.The results indicate that multi-parameter pseudo-sections,such as apparent resistivity and apparent chargeability obtained from inversion,clearly reveal a"low-high-low"vertical electrical structure of the strata in the exploration area.A distinct geophysical signature characterized by"low apparent resistivity and high apparent chargeability",was identified for the ore-bearing horizon(the Lower Cambrian Meishucun Formation).Strata exhibiting these electrical characteristics can be targeted as favorable zones for phosphate mineralization,which enables rapid spatial delineation of the phosphate-bearing strata.Furthermore,three fault structures(F1,F2,F3)were inferred and interpreted,leading to a preliminary understanding of the spatial distribution characteristics of the deep phosphate ore body.This exploration confirms that the CR method is sensitive to low-resistivity strata,achieves an effective detection depth of 1～1.2 km,and can significantly enhance the accuracy and efficiency of phosphate deposit exploration.It can serve as an effective geophysical technique for detecting similar types of concealed phosphate deposits.To address the issues of deep signal attenuation and the inherent non-uniqueness of geophysical interpretation,this paper proposes future improvements such as conducting borehole-to-surface joint inversion,integrating gravity and magnetic methods for comprehensive interpretation,and exploring the quantitative relationship between electrical parameters and phosphate grade.This study provides a scientific geophysical basis and methodological reference for the further exploration of the Yangchang phosphate deposit and for prospecting similar concealed sedimentary deposits.