Geochemical processes camouflaging original signatures in the thermal waters of south-central Chile

Several geothermal systems have been delineated and characterized along the Liquine-Ofqui Fault Zone, in the South-Central Volcanic Zone of Chile, from the geochemical signatures of the thermal discharges and structural analysis of the lineaments. Based on the ways of heating up of meteoric water, which is the feeder to these geothermal systems, two distinct domains of thermal discharges have been identified - (i) structural (or non-volcanic) and (ii) volcanic, the latter being directly associated with the regional volcanic centres. The process of heating is through deep circulation of meteoric water in the case of former; and absorption of heat and condensation of steam and gases by meteoric water during lateral circulation. However, these thermal discharges do not exhibit the typical signatures of steam heated waters, which are camouflaged or subdued by the means of water-rock interaction and other near surface processes.