用1∶25万分散流追踪异常源的方法及效果

Methods and effects for finding the anomaly sources by using 1∶25 000 dispersion flow

在甘肃西部干旱、半干旱荒漠区,Ⅰ,Ⅱ级水系发育或较为发育地区,利用1∶2 5万分散流加密工作方法对1∶10万或1∶5万分散流异常进行追踪评价。采样点一般布设在Ⅰ,Ⅱ级水系中,密度一般控制在35～40点/km2,样品为水系沉积物中—细粒的细砂。异常区以1∶5万分散流测量统计的背景值为背景值,以Ca=2(C0+RS)或Ca=2Ca′来确定异常下限值,对所圈定的异常区采用踏查确定其是否为矿致异常—地化综合剖面追查其异常源—探槽工程验证—利用地质勘查手段确定其工业价值的异常评价体系。近十年来,利用该方法在甘肃西部地区发现一批金、钨矿床。

Using 1∶25 000 dispersion flow to trade the 1∶100 000 or 1∶50 000 dispersion flow anomaly in the arid and half arid desert area where the Ⅰ,Ⅱ order water system developed well or rather good in the west of Gansu. The sampling points lay in the Ⅰ,Ⅱ order water system and 35～40 points per sq.km., the sample is the middle-granule silver sand in the water system sediment. Taking the statistical background value of 1∶50 000 dispersion flow as background value, using C_a=2(C_0+RS) or C_a=2C_a′ to determine the lower limit value of the anomaly, and evaluating the anomaly by the evaluate system of whether it is induced by ore or not—trace the anomaly source by geochemical general section—test it by trenching—make sure the industrial value by geological method in the anomaly area. Gold and tungsten deposit had been found by using this method at the west of Gansu in recent years.