Study On Geochemical Characteristics And Ore-Searching Prospects Of Jinya Gold Deposit,Northwestern Of Guangxi

Jinya gold deposit lies in Fengshan county, northest of Guangxi. It is a large scale micrograined-disseminated-type (carlin type) of Yunnan-Guizhou-Guangxi "gold-triangle", which located in the northeast marginal zone of Lingyun upwarping area in the Youjiang basin. Guangxi Zhuang Autonomous Region No.2geological team have explored in this area in the80’s. In recent20years, many geologists have made a lot of research work on it and got much progress. However, the study about geochemistry is not enough for Jinya gold deposit.The associations of ore-forming elements, the spatial distribution characteristics of elements and prospecting criterion are mainly discussed in this paper. The principal results are summarized as following:(1) Jinya gold deposit is a typical micrograined-disseminated-type in "Golden triangle" of Yunnan-Guizhou-Guangxi provinces. The ore bodies mainly existed in the Baifeng Group turbidite of middle Triassic. Ore bodies are controlled by the nearly NS-trending of Nayuan anticline and faults, and bedding slide fracture zone in the hinge of Nayuan anticline. Along the trend, ore bodies present the characteristics of expansion and shrinkage, thinning out and discontinuity and reversed "S" bending.(2) In this paper, the main mineralization periods were divided into two stages by field geological investigation, hand specimen and microscope petrography:stage1is major mineralization period with the mineral assemblage of gold, quartz, pyrite and arsenopyrite. Stage2with the mineral assemblage is gold, quartz, calcite, pyrite, arsenopyrite, realgar and stibnite. Based on synthesize analysis of ore-forming elements association and related host rock alteration, arsenopyrite and pyrite are considered as the main exploration criteria in Jinya gold deposit. This criterion is consistent with previous studies. While future gold mineralization exploration in the deep location or near district, arsenopyritization and pyritization, especially compared with extensive silication in fault zone can be regarded as prospecting criterion, and reflect the trace of ore-forming fluid.(3) Au-As-W are associations of ore-forming elements in Jinya gold deposit. These associations show two obvious characteristics of the distribution in space:①Au-As-W present rich in some part and poor in the other part, which is consistent with the characteristic of thinning out of gold orebody.②Au-As-W shows as the enrichment center that array to the north along the dip direction, or as the increasing tendency to the north along strike.(4) The ore-forming elements combination of Jinya gold deposit is similar with the elements associations of W-Au-Sb in Woxi gold deposit in west of Hunan province. The extension of gold ore bodies in Woxi gold deposit is more than1000m. However, W-beraing minerals have not been found in Jinya gold deposit at present. The ore body extends less than400m and the gold ore body still exist the extending possibility in deep location. Scheelite and wolframite could be found in the depth. According to the research of the space distribution features of ore-forming elements and orebody lateral trending, the northern deep location along the orebody strike could be considered as the prospecting direction for gold mineralization in the future.