1∶20万区域化探方法核心技术“取样粒级”的讨论

A DISCUSSION ON THE "SAMPLING GRADE",A KEY TECHNOLOGY IN 1∶200000 REGIONAL GEOCHEMICAL EXPLORATION

内蒙古区域化探扫面采用水系沉积物测量(或土壤测量),取粗粒级样品,取得了较好的地质找矿效果,但局部景观区找矿效果受到了一些影响。我国南北方水系沉积物中元素含量呈"U"形分布,反映了南北方不同的风化类型,以及所取不同粒级样品的物质成分也不同;取粗粒级和细粒级样品均可能有化探异常显示,采用-5^+20目(0.9 mm≤A<4 mm)和-120目(A<-0.125 mm)组合粒级作为采样粒级。为提高工效,取样时可以采用-5目(或-20目)全粒级物质,也能获取更多的找矿信息。这种取样粒级技术,也适宜于全国各种不同的景观区的不同尺度的水系沉积物测量和土壤测量的化探工作。

Stream sediment survey or soil survey was adopted during the 1：200 000 regional geochemical exploration in Inner Mongolia. The coarse sampling grade has performed well in the geological mineral resource prospecting. However, the prospecting is to some extent affected by local landscape. Geochemical elements in stream sediments from southern China are distributed in a ＂U＂-shaped pattern, which indicates the difference in weathering types and correspondingly the difference in sedimentary materials between northern and southern China. Both the coarse and the fine grade samples can probably reflect the anomalies, and therefore the -5 - ＋ 20 meshes （ -4 - ＋ 0.9 mm）and the - 120 meshes （ -0. 125 mm） samples should be adopted during exploration. For improving the working efficiency, even the -5 meshes （or -20 meshes） whole grade grains can be adopted. In this way, more exploration information can be acquired. This key sampling technology can also be applied to stream sediment survey or soil survey of different scales for various landscapes in China.