Application of Cl, B tracers and geoindicators to delineate some production characteristics of Mt. Labo geothermal system, Philippines

Abstract

This report focuses on interpretation on water chemistry in the Mt. area with respect to delineating characteristics of its waters. The types of waters in the area are: a) dilute neutral warm springs, b) alkaline hot springs, c) acid to neutral warm springs, d) slightly acid of 5.1 at 270?C) well waters, with relatively high so,. The source of supply of and B in the warm springs is the rock, with these waters react. On the other hand, the main source of supply of in the other types of water is considered to be the magma heat source to geothermal system. In these latter water types, however, most of the B is derived from the dissolving rock. The warm springs are considered to form by mixing of magmatic gases with surface waters, whereas, the alkaline hot spring waters and well fluids are formed by mixing of magmatic gases at depth. The acid to neutral waters are relatively far from equilibrium for secondary minerals, geothermometry results for these are not considered to be reliable. Quartz equilibrium temperatures (266 to 270 for the well discharges match accurately with the measured temperatures indicating that equilibrium is attained with respect to quartz in the reservoir.