Application of ICP-MS to Study REEs Geochemistry of Structure Alteration Rocks in Southwestern Guizhou Province, China

The structure alteration rocks (named as SBT) is the product of sedimentation, tectonization, and hydrothermal alteration. It is the major body hosting many ore deposits such as gold, antimony, and fluorite in Southwest Guizhou. Recently establishment and application of a metallogenic model based on the SBT made a significant breakthrough in gold prospecting in Southwest Guizhou. Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) was used to determine REEs concentrations of SBT samples from several typical ore deposits in Southwest Guizhou. The results show that: (1) ΣREEs concentrations of SBT from different locations are variable, ranging from 49.55×10^-6 to 271.72×10^-6 (in Table 1). (2) The SBT is enriched in LREEs, with LREEs/HREEs ranging from 5.62 to 13.59 (in Table 1). The REEs patterns normalized to North American shale and chondrite display enrichment of LREEs and distinct 'Four grouping' effect, indicating that they are the products of the same hydrothermal process (in Fig.2-Fig.4). The strongly positive europium anomalies in the Getang—Dachang area suggest the convergence of two hydrothermal ore fluid systems with different directions in this region. This study characterized the REEs content and its distribution in SBT from Southwest Guizhou Province, which is crucial for understanding the origin and evolution of ore-forming fluids, and provides guidance for gold prospecting in Southwest Guizhou Province.