基于水系流域的地球化学异常分析方法——以1：50000丫他幅水系沉积物分析为例

地球化学异常靶区优选一直是勘查地球化学所面临的核心问题。目前地球化学异常靶区优选所采取的方法,主要是基于不同地质构造单元的地球化学异常评价方法和基于多元统计而发展的多元素定量化评价指标方法,然而这些异常评价方法缺少对水系中沉积物的物质来源区域进行限定。由于在一级水系中沉积的水系沉积物主要由一级水系流域内的岩石经过风化、剥蚀、搬运,最后在水系内沉积而成,因此一级水系中的水系沉积物的物源区域可近似与水系流域等同。本文通过水系流域的提取,以水系流域作为分析单元,对1∶50000丫他幅水系沉积物进行地球化学分析评价,通过与地质矿产资料对比,证明了本方法的有效性,并且缩小了地球化学异常区域,更精确地进行靶区定位。根据本文提出的方法,通过分析区内已知矿点所处流域的地球化学元素特征,将丫他幅内已有金矿划分为两种类型,对后期找矿工作有一定的指导意义。

A Geochemical anomaly analysis method based on river basins: An example of the Yata area

Regional geochemical anomaly evaluation is a major problem that exploration geochemistry has long been facing. Now several conventional methods are commonly used for the evaluation, such as the geological-tectonic unit evaluation and multi-element quantifying index. These methods do not limit the source areas of sediments in river basins,and thus can not achieve good results. In general these sediments result from weathering, erosion and transport of rocks. So the provenances of them are identical with the river basin. In this paper, using the watershed as the unit, the geochemical anomalies are analyzed for the Yaya area on a scale 1:50,000. Comparison with the known mineral resources shows this method is effective. It can reduce the extent of geochemical anomalies and determine the target more accurately. Based on this approach, this work characterizes the geochemical elements of the watershed where ore spots have been discovered, and the existing gold deposits in the Yata area are divided into two categories, which will be able to guide the further ore-search efforts.