西北地区矿产资源潜力地球化学评价中成矿元素异常的圈定方法

Delineation method of metallogenetic element anomaly in mineral resources potential geochemical evaluation,northwestern China

地球化学方法是矿产资源潜力评价的重要手段,特别是在资源潜力预测评价的潜力区优选中尤为重要。但在工作实践中发现,用统一的异常下限圈定异常,常常会出现"有矿无异常或有异常无矿"的信息错位,给资源潜力地球化学评价工作中的异常定位造成困惑。经过对比分析认为:应用经滑动平均处理得到的滑动平均衬值数据绘制等量线图和相应的异常图,是解决区域性地球化学评价工作中异常信息错位的有效手段。在西北地区(包括各省区),滑动平均窗口大小选择49km×49km为宜。经过这种数据处理后圈定的异常图可以有效地解决异常信息错位现象,明显压制高背景异常,突出低背景区的弱小异常,同时也很好地显示了区域异常带的展布规律,间接地反映了区域构造和控矿构造的空间特征。

Geochemical survey is an important method of mineral potential evaluation,especially important to prefercial selection in mineral prospective area.But in practice if using the same anomaly threshold to outline all anomaly,locations of mineral occurence are usually different from boundary of anomaly.Based on comparative analysis,we found that it＇s an effective way using window moving average data to draw geochemical isoline map and corresponding anomaly map.In northwestern China （including five provinces）,the applicable length of moving average window is 49km×49km.The problem of anomaly dislocated can be solved by this way.High background values are obviously weakened and low background values are heightened in this way.At the same time,the distribution of regional anomaly belt is illustrated well and the spatial features of regional structure and ore-controlling structure are reflected indirectly.