Geochemical Research On Shenjiayao Gold Deposit In Xiaoshan, Henan Province

It has been pointed out that there is a good ore prospecting potential in Xiaoshan district, and ore prospecting should be further intensified. However, this area is mostly covered by Quaternary loess, which make the exploration difficult. The Shenjiayao gold deposit belongs to typical tectonic altered rock type deposit. This paper carried out its mineralogical and deep-penetrating geochemical studies for the Supplement to the previous studies. In addition, by the comparison of elements assemblage in the ores and geogas, this paper tested and verified the effects of deep penetrating geochemical prospecting method for hidden deposits in this area in the hope of providing a reference for the future exploration work.The ore body is dominated essentially by a NW-NNW strike fault. Massive and banded structure are common in the ores, and the major textures of ores are cataclastic texture, crumpled texture, metasomatic texture and so on. Ore compositional testing showed that the highest value of gold grade in ore samples is 36.65×10-6 and that of silver grade is 1.03. Cu, Pb, Zn and As is also rich in the gold ore. In chondrite-normalized REE patterns, the ore samples have shown the characteristics of slight LREE enrichment and negative cerium anomalies, which is similar to Yanshanian granite of Longwogou.With light microscope and scanning electron microscope, this paper found that ore minerals are mainly composed of pyrite, galena, arsenopyrite, sphalerite, and chalcopyrite. The main gangue minerals include quartz, siderite and sericite. Gold is present chiefly as electrum and native gold, mainly occurred in gold-carrying minerals(such as pyrite, galena, quartz and arsenopyrite) in the form of fissure gold, inclusion gold or intercrystalline gold. In addition, a small amount of argentite and gustavite were also observed. The formation of gold minerals is closely related to polymetallic sulphides. According to the results of Electron microprobe analyses about pyrite, Sphalerite as well as other minerals, it is found that the main mineralization occurred in the middle and low temperature hydrothermal conditions and the ore-forming hydrothermal solution originated from the mixing of magmatic water and meteoric water.Using the method of Geogas, this paper researched the characteristic of spatial distribution of elements in the mining area. We took use of foam plastic and aqua regia to collect geogas samples, and the number of each kind of samples is 163. Based on the content isograms of a total of 12 elements(consist of Au, Ag, Cu, Pb, Zn, As and other 6 elements), it was found that there were distinct anomalies of these 12 elements above the ore deposits. The anomaly is strip in shape and accords with the NW-striking deep-level ore body. The element associations of anomalies reveal a high-ranked consistency and correlation with the mineralization element in ores and the ore mineral assemblage. Furthermore, REE in geogas samples and ores have the same character and thus suggest that the anomaly of elements in geogas are derived from the ore deposits. The ore-prospecting results of deep-penetrating geochemistry in this area is greatly authentic.