Geochemistry, geothermometry and influence of the concentration of mobile elements in the chemical characteristics of carbonate-evaporitic thermal systems. The case of the Tiermas geothermal system (Spain)

Abstract

The Tiermas low temperature geothermal system, hosted in the Paleocene-Eocene carbonates of the Jaca-Pamplona basin, has been studied to evaluate the geochemistry and the temperature of the waters in the deep reservoir. These waters are of chloridesodium type and emerge with a temperature of about 37 ºC. Two hydrogeochemical groups of waters have been distinguished: one with lower sulphate concentration and lower TDS (about 7,500 ppm) and the other with higher sulphate content and TDS values (close to 11,000 ppm). There are also slight differences in the reservoir temperature estimated for each group. These temperatures have been determined by in the vicinity of the injection well due to desiccation of the waters and, 2) carbonate dissolution and sulphate precipitation in the long term.

Geochemical evolution of thermal waters in carbonate – evaporitic systems: The triggering effect of halite dissolution in the dedolomitisation and albitisation processes

“…These geothermometers have provided coherent results in some systems similar to the ones studied here (e.g. Apollaro et al, 2012;Blasco et al, 2018Blasco et al, , 2017Fernández et al, 1988;Gökgöz and Tarkan, 2006;Michard and Bastide, 1988;Mohammadi et al, 2010;Pastorelli et al, 1999;Wang et al, 2015) and, therefore, their applicability in the Fitero -Arnedillo geothermal system is tested. Classical chemical geothermometers and calibrations used in this study are:…”

“…The temperatures obtained with this last calibration (CaSO4-H2O exchange) are the most reasonable ones since anhydrite is in equilibrium in the system (see below) and, they are in the range previously defined with the chemical geothermometers. The bad results obtained with the calibration based on SO4 2-(despite being the dominant sulphur species in this type of waters), are probably due to the lack of equilibrium between SO4 2and H2O (Blasco et al, 2018(Blasco et al, , 2017Boschetti et al, 2011). On the contrary, although, the HSO4 is not the main species, the calibration based on it provides good results because it is very similar to the CaSO4-H2O calibration in a 10 3 lnα -10 6 /T 2 plot (see Blasco et al, 2018).…”

“…Bischoff et al, 1994;Cañaveras et al, 1996;López-Chicano et al, 2001;Moral et al, 2008), in deeper aquifers and thermal waters with variable salinity (e.g. Auqué et al, 2009;Back et al, 1983;Blasco et al, 2017;Frondini, 2008;Plummer et al, 1990; Prado-Pérez and Pérez del Villar, 2011) and even in brines during burial diagenesis (e.g. Budai et al, 1984;Stoessell et al, 1987;Woo and Moore, 1996 and references therein).…”

“…These issues were thoroughly treated in the previous study on the Arnedillo waters (Blasco et al, 2018) and, therefore, only some observations are included here. In any case, as both systems belong to the same reservoir, the study of the Fitero thermal waters will improve the general understanding in the particularities of the use of these geothermometers (as explained in Blasco et al, 2017).…”

Hydrochemical Characteristics and Evolution of Geothermal Fluids in the Chabu High-Temperature Geothermal System, Southern Tibet

“…The ion charge imbalances for the water samples were calculated using the program AquaChem, and the results showed that all of the samples have a charge imbalance less than ±5% (Table 1). Values in this range are usually accepted as valid and can support the reliability of the data used in this work [25][26][27].…”