Relation between the characteristics of magnetic susceptibilities of altered rocks and gold mineralization in the Qianhe gold deposit, Henan

Abstract：The Qianhe gold deposit, Henan, is of tectonic alteration type. In this deposit, orebodies show gradational contact relationships with wall rocks with a vague boundary, but there is distinct difference in magnetic susceptibility among orebodies, wall rocks and various types of altered rocks. Systematic susceptibility measurements were made of altered rocks in various levels and along exploratory lines of the Qianhe gold deposit using a WCL-1 portable contact magnetic susceptibility meter. The susceptibility values of various kinds of typical altered rocks are in decreasing order as follows: chloritized rocks (Ch) → silicified-chloritized rocks (Si+Ch) → chloritized-silicified rocks (Ch+Si) → K-feldspathized rocks (Kf) → silicified (Si) → pyritized-phyllic rocks (Py+Se+Si). Correlation analysis of the magnetic susceptibilities of altered rocks and degrees of gold mineralization indicates that there is a negative correlation trend between them. Profiles of magnetic susceptibilities of altered andesite along lines 78 and 83 and a vertical longitudinal projection map of magnetic susceptibilities and gold grade isolines in the ore district have been constructed, and the direction for looking for ore deposits at depth in the ore district has been predicted preliminarily.