Element Dispersion and Wall-rock Alteration from Daebong Gold-silver Deposit, Republic of Korea

The Daebong deposit consists of gold-silver-bearing mesothermal massive quartz veins which fill fractures along fault zones(N10 similar to 20 degrees W, 40 similar to 60 degrees SW) within banded gneiss or granitic gneiss of Precambrian Gyeonggi massif. Ore mineralization of the deposit is composed of massive white quartz vein(stage I) which was formed in the same stage by multiple episodes of fracturing and healing and transparent quartz vein(stage II) which is separated by a major faulting event. The hydrothermal alteration of stage I is sericitization, chloritization, carbonitization, pyritization, silicification and argillization. Sericitic zone occurs near and at quartz vein and includes mainly sericite, quartz, and minor illite, carbonates and epidote. Chloritic zone occurs far from quartz vein and is composed of mainly chlorite, quartz and minor sericite, carbonates and epidote. Fe/(Fe+Mg) ratios of sericite and chlorite range 0.36 to 0.59(0.51 +/- 0.10) and 0.66 to 0.73(0.70 +/- 0.02), and belong to muscovite-petzite series and brunsvigite, respectively. Calculated Al-IV-Fe/(Fe+Mg) diagrams of sericite and chlorite suggest that this can be a reliable indicator of alteration temperature in Au-Ag deposits. Calculated activities of chlorite end member are a3(Fe5Al2Si3O10(OH)(6)=0.00964 similar to 0.0291, a2(Mg5Al2Si3O10(OH)(6)=9.99E-07 similar to 1.87E-05, a1(Mg6Si4O10(OH)(6)=5.61E-07 similar to 1.79E-05. It suggest that chlorite from the Daebong deposit is iron-rich chlorite formed due to decreasing temperature from T>450 degrees C. Calculated log alpha K+/alpha xH(+), log alpha Na+/alpha H+, log alpha Ca2+/alpha H-2(+) and pH values during wall-rock alteration are 4.6(400 degrees C), 4.1(350 degrees C), 4.0(400 degrees C), 4.2(350 degrees C), 1.8(400 degrees C), 4.5(350 degrees C), 5.4 similar to 6.5(400 degrees C) and 5.1 similar to 5.5(350 degrees C), respectively. Gain elements (enrichment elements) during wallrock alteration are K2O, P2O5, Na2O, Ba, Sr, Cr, Sc, V, Pb, Zn, Be, Ag, As, Ta and Sb. Elements(Sr, V, Pb, Zn, As, Sb) represent a potentially tools for exploration in mesothermal and epithermal gold-silver deposits.