Application of high-frequency magnetotelluric method in porphyry copper deposit exploration：a case study of Duobaoshan deposit area

摘要

The Duobaoshan mine area in Heilongjiang is located in the northeast section of Xingmeng orogenic belt and is in the west side of Hegang Mountain-Heihe fault zone. There exist many deposits in this area,and its metallogenic conditions are superior,which has been one of the hotspots in geological prospecting and metallogenic research in Northeast China. On the basis of previous studies,the authors used the EH-4 electromagnetic imaging system to carry out the data acquisition of three survey lines in Woduhe Village,Duobaoshan Town,Nenjiang County. Through the analysis of apparent resistivity section under TE and TM polarization modes,integrating regional geological data,it is concluded that:(1) the electrical characteristics of the metal ore in this area show a relatively low resistance,and according to its resistivity difference with surrounding rocks,the geometrical structures and apparent resistivity parameters of the low resistivity bodies in the lower section of the survey line are defined,and the electrical anomalies can be identified;(2)faults F1 and F2 may have a good metallogenic environment,so they are recommended for further exploration;(3) low resistance metal ore bodies have good correlation with local small structures or faults,which may play an iconic role for the delineation of key target areas;(4) in the process of using apparent resistivity to define the geometric structures of ore bodies underground,comprehensive analysis integrating the advantages of TE and TM models should be carry out to achieve more reliable inversion results.