The Structural Superimposed Halo And Metallogenic Prognosis Study Of The Dawangding Gold Deposit, Guangxi, China

The Dawangding gold deposit located in the Gupao Town of Zhaoping County, is one ofthe most important and newly discovered gold deposits in the Gupao gold ore field. In order tofigure out the distribution of the ore body and the potential of the resources, structuralsuperimposed halo and metallogenic prognosis study of the Dawangding gold deposit aresystematacially carried out in this dissertation. Combined with comprehensive study of itsdeposit geology and ore-forming geochemical background, the following achievements areobtained.1. In the mining district, three-dimensional morphology of the ore body is controlled bythe Dawangding intrusion, nearly EW-striking and NE-striking faults. The ore body strikesnearly EW, with the trend of W and NNW in the north of the Dawangding intrusion, whereasin the south it turns into west.2.According to computing the geometric mean of10background samples from the wallrock in the mine, the elements of Bi, As, Au, Pb, Sb, W, Sn, Ba and Ag are enriched. Andthrough doing this, the geochemical background of the indicator elements are obtained, whichprovides the standard for the structural superimposed halo anomaly analysis.3.Based on systematic collection of709samples and analysis of their contents of18elements, the element assemblage and their quantitative geochemical characteristics of theDawangding gold deposit have been obtained. A series of structural superimposed halo chartsof each element have also been made in the three-dimensional space, which lay the foundationfor variation analysis on the axial zoning of the primary halo. We have also made distributioncharts of the18elements in order to reflect activity rule of the ore-forming fluid. Based on this,the ore body has been delineated again, which can better reveal the distribution of the orebody.4.Section and vertical projection drawings of the structural superimposed halo inDawangding gold deposit have been made. The corresponding metallogenic pattern of headhalo, near-ore halo and tailing halo has also been set up.The near-ore halo is composed ofAu、Ag、Cu、Pb, the head halo ofAs、Sb、Hg and the tailing halo of Mo、Bi. TheAu element hasone or more abnormal centers. The halo of the ore body, derived from different ore-formingprocessed, is characterized by apposition, or near apposition, or part apposition, or some ofthem is characterized by superimposed structure of the hailing halo of the upper ore and the head halo of the blind ore. This helps to better reveal the superimposed rule of thehydrothermal halo and also to build the structural superimposed halo metallogenic pattern inthe Dawangding gold deposit. Thus, we suggest that the best indicator elements of theDawangding gold ore body are Au, Ag, As, Sb, Hg, Cu, Pb, Zn, Bi, and Mo, which helps toconfirm mark of the structural superimposed halo used to predict the blind ore.5. According to the above indicative mark of the blind predicting, the prospecting targetsof41blind ore and one favorable ore-forming location have been proposed.6.The contrast values of the18elements studied in the Dawangding gold deposit aresignificantly lower than the other known gold mines. This shows that the metallogenichydrothermal activity is not strong in the Dawangding gold deposit, and thus indicates that themineralization scale is smaller than other mines studied before.As a representative in the Dayaoshan gold metallogenic region, structural superimposedhalo study of the Dawangding gold deposit provides a great help for the next exploration ofDawangding deposit and also for the other gold mines in the area. But there are only threedifferent middle sections, resulting in that the samples collected from the tunnels are notenough. Besides, there are also structures destroying the ore body, so the ore-controllingregularity is more complex and the representative samples are limited. All of the above factorslimit in-depth study of the geochemistry of the Dawangding deposit. It is suggested that thetracking study should be continued with the increasing of the mining middle sections. Inaddition, the structural superimposed halo metallogenic pattern is prospecting of unknown oresbased on the known ore deposits, which also needs to statistically analyze the existing data. Inconclusion, although the pattern has been widely used in many gold mines, it also needsfurther theoretical study for improving because of the complexity of the ore-forming processin various geological factors and aslo the complex formation mechanism of the primary halozone in hydrothermal deposits, etc.