Análisis de la fracturación y campos de paleoesfuerzos en el centrooeste de la Península Ibérica.

Abstract

The Tormes Dome is a granitic massif emplaced during the Hercinian orogeny and later deformed by several posthercynian fracturation episodes. Three main paleostress fields have been obtained from stress inversion o f 1375 fault-slip data collected throughout the study area. The maximum horizontal stress (SHMAX) are oriented N-S, NE-SW and E-W with extensional and strike-slip stress regimes. Difficulties to determine age dating o f the three paleostress fields made necessary to enlarge the study area to the surrounding Cenozoic basins borders. In addition, geocronological information obtained form K-Ar dating o f fault gouges collected in the Tomes Dome has been used to establish the relative chronology of the three tectonic episodes from field data and determine their activity periods form Mesozoic to present time. An important result is that there is no relevant brittle tectonic activity associated with the recent NW-SE stress field in the western peninsula from Upper Miocene to the present times and some field evidences, as well as two focal mechanisms of earthquakes occurred in the area seem that in the Tormes Dome the recent stress field present an Shmax oriented N-S.