Travertinos asociados a la actividad de la Falla de Alhama de MurciaEstudio geoquímico para la caracterización de una falla de desgarre

Abstract

The Alhama de Murcia Fault (FAM) is a major seismic source in the Iberian Peninsula. Over the last 20 years, efforts have been focused on the fault characterization through paleoseismic, geodesic, seismotectonic and structural stu- dies in an attempt to reduce the seismic risk in the area. In this work, we use the geochemical analysis of the carbo- nate deposits (travertine) associated to the fault activity as a new tool for the determination of the seismic history of the FAM. The geochemical and geochronological determination of these deposits informs us about the ruptures his- tory and can provide fundamental data for seismic hazard assessment (Temiz et al., 2013; Vignaroli et al., 2016). Northeast of Lorca city, coinciding with ancient Carraclaca’s thermal baths, there are travertine deposits related to the FAM. The stable isotopes δ13C and δ 18 O analysis carried out in the Carraclaca’s travertine confirm its thermogenic origin. The tra- vertines are the result of the precipitation of carbonates dissolved in deep water, transported to the surface through the fault during seismic events. The analyses also indicate that there is an interaction between deep waters and surficial aquifer, which causes an enrichment in the isotopes signature. It seems, therefore, that there is a direct correlation between FAM activity and travertine formation in the Carraclaca area.