Geophysical Characteristics and Prospecting Direction of Orogenic Gold Deposits in Yanbian Area, Jilin Province：Taking Haigou Gold Deposit as an Example

Jiapigou-Haigou-Jinchengdong tectonic-magmatic (complex) belt is an important gold metallogenic belt in Jilin Province. Haigou gold deposit is located in the middle of this tectonic-magmatic (complex) belt. It underwent the superimposition of multi-period of magma parallel penetration in Paleozoic and Mesozoic, fracture of different properties (toughness and brittleness) in different time and different types of structures (ring, arc mixed with linear). These geological events have extremely complex relationship with gold mineralization. deep metallogenic prediction of Haigou gold deposit has become a top priority. In this paper, such geophysical methods as magnetic method, gravity method and magnetotelluric method of controllable source audio-frequency are used to analyze the geophysical anomalies of surface-shallow, middle and deep parts of Haigou gold deposit. The surface and shallow ore-controlling structures of Haigou gold deposit are ductile-brittle structural transition and brittle structures. The middle ore-controlling structures are controlled by the ductile shear zone of greenschist facies. And the deep ore-controlling structures are mainly controlled by the ductile shear of amphibolite facies. Therefore, the geophysical field characteristics of different depths are the distinguishing indicators of controlling gold deposits.In the magnetic low-gentle positive anomaly, the localized high anomaly spike location layer and shallow ore-controlling structure, the gravity positive and negative anomaly gradient zone locates the middle ore-controlling structure. And the steep low-resistivity anomaly zone locates the deep ore-controlling structure. The deep-to-shallow ore-controlling structures reflect the changes of geophysical field characteristics in the transformation of the dynamic mechanism of continental crust, such as continental tension, uplift-slip and detachment structures. by comparing the geophysical characteristics of typical gold ore belts, whether or not there is this type of gold deposits in the deep and periphery is predicted.