黄土覆盖区地球化学数据采集及采样单元之间误差校正方法研究——以内蒙古敖汉旗为例

GEOCHEMICAL DATA COLLECTION AND ERROR CORRECTION FOR SAMPLING IN LOESS COVERED AREAS: A Case Study of Aohan County, Inner Mongolia

敖汉旗幅为赤峰地区的黄土覆盖区,在该区进行1∶5万区域地球化学调查工作以水系采样为主,土壤为辅.为便于研究,水系粒级采用-10^+60目,土壤样品采用-10目粒级.因采样介质不同,所代表的化学意义不同,测试中产生系统误差.对不同采样介质的测试数据以Au元素为例分别进行统计,确定不同采样地区的背景值,并利用不同的系统误差校正方法对土壤采样区与水系采样区进行系统误差校正,以求在满足异常分析的同时更低程度遗漏厚黄土覆盖区低缓弱异常.3种校正方法在保证水系沉积物异常条件下,对黄土区异常都有一定程度弱化.标准化方法弱化的程度相对小,对刻划黄土区地球化学信息最接近,衬度变换与中位数变换校正后对黄土区地球化学信息反映弱.

Aohan County is located in the thick loess covered area of Chifeng region, Inner Mongolia. The 1：50 000 regional geochemical investigation in the area involves mainly stream sediments sampling, supplemented by soil sampling. The study is carried out by using -10 - ＋60 mesh granularity of stream sediment samples and -10 mesh granularity of soil samples in loess covered area. However, due to different sampling media, which represent different chemical significances, there are system errors in testing. In this paper, the experimental results of different media are calculated divisionally, taking Au for example, to determine the background values of different sampling areas. In addition, different methods are adopted to correct the system errors between soil and stream sediment samples, in order to meet the need of anomaly analysis and avoid omitting the low weak anomalies as far as possible. The three methods weaken the anomalies of loess covered area in some degree, although the stream sediment anomalies are confirmed. The standardized method causes a less weakening to the anomaly, which is most close to the geochemical information of loess covered area; while the correction methods of contrast transformation and median transformation reflect weaker geochemical information.