| Abstract |
Mahanagdong area in Leyte hosts an active hydrothermal system within high-ang1e)actures system. The fluitis have maximum temperature of 300"C, salinity of 0.20m in terms of Cl, and gas contents of 3.0% by weight. .The d80 in water of -3.0 to -1.o"/, indicates mixing of about 6580% groundwater with 20-35% original magmatic components. With H2S as the dominant surfw species, the present-dq lydrothermaj system appropriately belongs to low-su@dation, epithermal environment. Mahanagdong hydrothermal system will unlikely support deposition of metals transported in bisu@& complexes, like gold silver and mercuy, because the fEuids have already attained near neutral-pH level probably through the process of water and rock interaction. The low total su&w content of the fluids (0.004m) mcry be primarily transporting arsenic complexes, the most abundant h e q metal species in Mahanagdong fluids. Arsenic increases with decline in temperahre and is expected to disperse further in supergene environment. Metals transported by CI complexes such as zinc and lead tend to decrease from the hot and saline central part of thejield towar& the cooler and dilutedperipheral sectors. Degassing and increase in pH, the consequences of boiling, appear to favor deposition of these metals. On the other hand. iron and copper, which m also transported by CI complexes, have lower correlation with temperature, salinity andfluidpH. Their mobility is also controlled by other factors, such as the redox state. Having low solubilities, iron and copper are the most dominant metal forming minerals, in form ofpyrite and chalcopm*te, in Mahanagdong. |