The Metallogenic Model And Prospecting Target Assessment Of Awen Gold Deposit In Laos

The Awen gold deposit is newly discovered by Hei Bei Constructions & Investment Group Co. Ltd Laos Tonglian Co. Ltd at 2002 in the southeastern part of the Truongson Fold Belt with NW-NNW trend, Laos. The gold deposit comprises 13 identified gold-bearing veins, which are restricted to the NW-NNW trending faults zone. Orebodies are hosted in low grade metamorphic rocks, which have characteristics of turbidite sedimentary, are composed of metasiltstone, metamalostone, slate and phyllite.There are two main styles of mineralization in the deposit:(1) mineralization in the altered host rocks, and (2) auriferous quartz veins, principally associated with pyrite.Hydrothermal alteration including silicification, pyritization, sericitization and carbonatization is well developed around the orebodies and shear zones. Silicification, pyritization, and sericitization are spatially associated with the gold mineralization. Pyrite is widely distributed, occurring as veinlets disseminations. The primary fluid inclusions occur as mono-phase and two-phase (liquid+gas) inclusions, rarely as three-phase inclusions containing with liquid CO2. The homogenization of fluid inclusions indicates that ore deposition took place between 118.5℃ and 376.1℃, mainly at 160℃-240℃. Freezing temperatures of fluid inclusions were measured between -22.8℃ and -1.7℃, and the estimated salinities range from 1.05-24.21 wt% NaCleqv. Their corresponding densities were estimated in the ranges of 0.733-1.044 g/cm3. Temperature and salinity histogram weakly show a bimodal structure, indicating that there may be two-stage fluid activity. Raman spectra show that vapor bubbles of inclusions have a certain amount of CO2. Fluid inclusion studies they plot in the field of epithermal mineralization and lode Au deposit with their low Th and salinity values.Concentration coefficient of the elements in ores are ranked in decreasing order according to the K-value:Au, As> Bi, Sb, Ag> Ba, W, Mo. cluster analysis divide those elements into three groups:an Au-Ag ore-forming element group, an As-Sb-Cu-Mo element group and a Cr-Ni-Bi element group.δ34S values for pyrite from gold ore veins are ranging from+4.0 to+15.2‰ with most of the values clustering between+12.0 and+13.5‰. The δ34S values of sulfides separated from gold veins are similar to those of sedimentary strata. The calcite samples of the ore veins have δ13CPDB of-2.0 to-3.3‰. This indicates that CO2 of ore fluids were probably sourced from a magmatic system, perhaps with some input from metamorphic decarbonation of carbonate strata. The δ18OSMOW ratios of calcite range between+14.02 to+14.75‰, Calcite crystallized from a Co2-bearing fluid with a δ18O fluid component ranging from+4.76～+5.41‰. hese values lie within the range with magmatic or metamorphic source calculated δ18O fluid values. In conclusion, the Awen gold deposit is characteristics of orogenic gold deposits.We study stream sediment sample mapped at scale 1:50000 and soil mapped at scale 1:10000 by geostatistical method. The results of factor analysis illustrate that Au is not Symbiotic with other ore-forming elements. Then, the target area created by Kriging and the BEMD that the anomaly thresholds calculated by Iterative method and’C-A’fractals. There are assessments of anomaly for 7 A target areas and 7 B target areas in Awen gold deposit.