徐宿弧(安徽段北部)弱磁异常特征及其认识

查明徐宿弧(安徽段北部)隐伏岩体的赋存状况,圈定岩体与围岩的接触部位及找矿靶区并推测赋矿部位,是实施徐宿弧(安徽段)金多金属矿成矿背景调查的主要任务。徐宿弧(安徽段北部)为弱磁异常区,实测磁异常形态凌乱且难以识别。首先通过化极、滑动平均、匹配滤波、垂向一阶导数及向上延拓等方法进行多方法多参数变换数据处理,从弱磁异常中提取形态规则、易于识别的低缓异常; 然后对处理结果进行甄别对比,筛选出异常形态特征有利于地质解释的磁异常图,即: 低缓磁异常为叠加异常,总体呈NW方向延伸,覆盖面积较大,次级异常呈NNW-NE方向西凸的弧形延伸至前欧盘。同时,依据徐宿弧(安徽段北部)的地质背景及岩(矿)石磁性参数特征,通过对比分析实测磁异常与前欧盘闪长玢岩引起的磁异常特征,推测引起低缓异常的磁性地质体为隐伏中酸性复式岩体。该研究为徐宿弧(安徽段)金多金属矿成矿背景调查的综合解释及圈定找矿靶区提供了参考。

Weak magnetic anomalies characteristics and its recognition in Xu-Su arcuate structure (north of Anhui section)

The main tasks of metallogenic background survey of gold polymetallic deposit in Xu-Su arcuate structure (north of Anhui section) are ascertaining the occurrence status of concealed rock bodies in Xu-Su arcuate structure (north of Anhui section), delineating the contact area between rock bodies and surrounding rocks and the target area, and speculating the ore bearing position. The Xu-Su arcuate structure (north of Anhui section) is a weak magnetic anomaly area, and the measured magnetic anomalies are disordered and difficult to recognize. Through multi-parameter transformation process, such as reducing to the pole, moving average, matched filtering, vertical first derivative and upward continuation, the authors extracted low anomaly of the regular shape and easy identification from the weak magnetic anomalies. The processing results were screened and compared. Then the abnormal magnetic features which are favorable for geological interpretation were screened out. The results show that weak magnetic anomalies are superimposed anomalies in NW extension and have large coverage areas. Secondary anomalies are in NNW-NE direction and the west convex arc extends to the Qian’oupan. According to the geological background of Xu-Su arcuate structure (north of Anhui section) and the magnetic parameters of rocks (ores), and through the comparative analysis of measured magnetic anomalies and magnetic anomaly characteristics of Qian’oupan diorite-porphyrite, the authors speculated that the low anomalies are caused by the concealed intermediate-acid complex rocks. The research provides some reference for the comprehensive interpretation of the metallogenic background survey of gold polymetallic deposit in Xu-Su arcuate structure (north of Anhui section) and the delineation of the target area.