Eduardo González Partida

Isotopic zoning and origin of the aquifers in the discharge area of the geothermal fields of ahuachapán and Chipilapa, El Salvador

Abstract The northern discharge areas of the Ahuachapan, and Chipilapa geothermal fields can be subdivided into four different zones based on their structural position, and the isotopic and chemical composition of their waters. In general, the contribution of geothermal waters from these two fields was estimated to be less than 10%. Elevation effects are of little importance, whereas a slight trend towards higher isotopic values with increasing water temperatures may exist. The NNW-SSE-trending Escalante and Agua Caliente faults represent lateral groundwater barriers, and provide vertical conduits for the ascending geothermal waters. The western discharge areas seem to be more influenced by the Ahuachapan, geothermal field, whereas those to the east are more influenced by the Chipilapa field. Groundwaters in the Northern Plain are mainly from shallow northward-flowing aquifers. These waters show temperature effects, mixing with geothermal waters and are affected by the geology of the area. However, none of these factors alone can explain the isotopic variations observed in the waters of the northern discharge areas.

Magnetostratigraphy of the Ahuachapán-Chipilapa geothermal field, El Salvador

Abstract The volcanic stratigraphy for the Ahuachapan-Chipilapa geothermal field is defined on the basis of the magnetostratigraphic results on 156 oriented samples from 33 sites. The magnetostratigraphic sequence shows that the major volcanism associated with the Concepcion de Ataco caldera and the Cuyanausul volcano took place during the middle Brunhes chron (Quaternary). Pre-caldera activity of small centers such as Empalizada and Apaneca in the southern sector of the field occurred during the early Brunhes (0.77±0.07 Ma). Basaltic-andesitec activity associated with the Cuyanausul volcano took place earlier, i.e. during the Matuyama chron, possibly around 1.3±0.15 and 1.7±0.3 Ma.The local igneous basement is composed of Late Miocene-Pliocene andesites, ignimbrites and volcano-sedimentary deposits. Normal polarities and a KAr date of 7.37±0.73 Ma indicate that the volcanic activity in the study area extends beyond the Gauss chron. The polarity of some of the units in the post-caldera sequence and in the Concepcion de Ataco and Cuyanausul sequences suggests that they may have recorded short polarity subchrons.

Thermodynamic state updated of the volcanic caldera and geothermal reservoir of Los Humeros, Puebla, Mexico

Based on information of enthalpies of the fluids of wells from the geothermal reservoir of Los Humeros, Puebla, Mexico, we determined the thermodynamic conditions of the reservoir comparing the values of enthalpies of the fluids of discharge of the wells with the values published in the literature for different thermodynamic state of fluids.

Thermodynamic model for the phase equilibria of gases and brines. Example in the H2S-H2O-NaCl system

We present a thermodynamic model for the phase equilibria of gases and brines, which couples Henrys Law with the Soave?Redlich?Kwong equation of state to reproduce experimental data. In this communication we focus on the H2S H2O NaCl system.