化探方法技术之取样粒度研究——以豫西牛头沟金矿1∶5万化探普查为例  

Sample Granularity of Soils and Stream Sediments in Geochemical Surveys: A Case Study of the Niutougou Gold Deposit,Xiong'ershan Gold Mine in Hennan Province

作　　者：贾玉杰[1] 龚庆杰[1] 韩东昱[1] 刘宁强[1] 夏旭丽[1] 李晓蕾[1] 

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《地质与勘探》2013年第5期928-938,共11页Geology and Exploration

基　　金：中国地质调查局地质调查工作项目(1212011120950);国家科技支撑计划课题(2011BAB04B09)资助

摘　　要：水系沉积物测量在我国是一门比较成熟的技术,但在不同的表生环境条件下开展水系沉积物测量的最佳采样粒度也不尽相同。通过对豫西熊儿山金矿田牛头沟矿区不同粒度土壤和水系沉积物样品风化过程中元素行为的研究,发现土壤和水系沉积物样品随粒度变细其风化程度增强,且这一特征在水系沉积物样品中表现更为明显。当样品粒度为4～100目时,元素含量逐渐升高或降低,变化趋势较为稳定;当粒度小于100目时,样品中元素含量发生显著变化,其主导风化机制可能发生了改变。热液成矿元素在土壤样品中相对富集在60～100目的粒度,在水系沉积物样品中相对富集在80～100目的粒度,参考各粒级样品在全粒级样品中的质量分数,建议选择60～100目作为水系沉积物测量的最佳采样粒度。这一粒级样品既可继承原岩在连续风化过程中的元素行为,又不受后期新的风化机制的明显影响,同时可最大限度地风化而分散以达到降低采样密度的需要。选择60～100目粒级样品在牛头沟金矿区开展了1∶5万化探普查,结果发现元素浓集中心与各矿段空间位置吻合较好,为豫西熊儿山地区开展1∶5万化探普查提供了技术参考。Although the measurement of stream sediments has become a relatively mature technology in China, the optimal sampling granularity of stream sediments remains variable in different supergene environments. In this paper, element behavior of different granularity soils and stream sediments in weathering processes is investigated taking the Niutougou gold deposit of the Xiong＇ ershan gold mine in western Hennan Province as an example. The results show that the weathering degree of soils increases with the decreasing soft granularities. This behavior is also found in the stream sediments and is clearer than that in the soils. Element content shows a stable trend in soils or stream se,,diments when the sample granularity decreases from 4 to 100 mesh （ or 2 - 0.154 mm）, but the element content changes sharply when granularity is less than 100 mesh （or 0.154 mm）. This sharp change may be resulted from the transfer of weathering mechanisms. Hydrothermal ore-forming dements are concentrated in the 60 - 100 mesh granularity in soils and 80 - 100 mesh in stream sediments, respectively. The sample granularity of 60 - 100 mesh is optimal for the measurement of stream sediments in the Niutougou gold deposit. This granularity of soil or stream sediment samples not only inherits the element behavior of their parent rocks, but also is weathered sufficiently to represent their source rocks and thus to meet the need of decreasing sampling density. The geochemical survey at a scale of 1：50000 was carried out in the Niutougou gold deposit choosing the sample granularity of 60 - 100 mesh, and the results indicate that the concentration centers of elements coincide with the ore blocks in the ore district. This result validates the feasibility of sampling granularity and provides guidance for geochemical surveys in the Xiong＇ ershan gold mine.

关 键 词：化探方法技术 采样粒度 熊耳山 牛头沟金矿 水系沉积物 

分 类 号：P618[天文地球—矿床学]