湘南骑田岭地区锡多金属矿体的磁法找矿标志研究

A PRELIMINARY STUDY OF PROSPECTING INDICATOR OF MAGNETIC METHOD IN THE QITIANLING TIN POLYMETALLIC MINE,SOUTH HUNAN PROVINCE

中高山地区找矿的地质标志由于地面工作的困难而不易充分使用,如能利用物探特别是航空物探的指标作为有效的找矿标志,则具有实际的经济价值。文章分析骑田岭地区占总储量1/3的19号矿脉(体)的航磁异常时,发现较低精度的航磁异常的幅值不适于作为寻找该矿体的找矿标志;而利用航磁异常梯度刻画的磁结构则能完美地定位19号矿脉(体)的空间位置,“磁异常梯度矢量交汇处”是一个可能的有效的找矿标志。初步研究假设认为,流体的作用改变了区域岩石磁性的结构以及磁场的结构,磁异常梯度矢量与流体运移方向具有某种内在联系,利用磁异常梯度矢量可模拟研究区所发生过的成矿流体场的作用特征,找到成矿流体所可能的汇聚位置,从而确定成矿作用所发生的空间位置。

Due to difficulty of geological criteria for ore prospecting applied in the middle - high mountain area, it is suggested that geophysical ore - hunting indicator, special aeromagnetie exploration, may be used. Aeromagnetie anomalies are used for finding indicators of No. 19 ore vein, which tin reserves occupy 33% in the Qitianling tin - polymetallie mine, Hunan province, South China. It is shown that amplitude value of aeromagnetie anomaly with low precision could not be used as clue of prospecting, and however, intersection of anomaly magnetic field gradient vector could locate space of dominant ore vein perfectly. It is suggested that structure of anomaly magnetic field gradient vector could be a prospecting criteria used in the area. Based on primary studies, ore -forming fluids have altered structure of magnetic mineral in the rocks that may change the structure of anomaly magnetic field, and the gradient vector of anomaly magnetic field may simulate flow direction of ore - forming fluids. The confluence of ore - forming fluids is favorable place for mineralization, so that the intersection of anomaly magnetic field gradient vector may be possible place for prospecting.