The Gredos massif (Spanish Central system): a global example of magmatic processes at the emplacement level

Abstract

The Gredos massif occupies the central part of the Spanish Central system batholith. It primarily comprises calc-alkaline granodiorites and monzogranites rich in alkalis, with lesser amounts of leucogranitic and basic rocks. In areas where detailed studies have been conducted, the intrusive units form tabular bodies emplaced within the metamorphic rocks that constituted the mid-crust during the Late Carboniferous, remaining as septa of metasediments and migmatites between the intrusive sheets. The recent history of uplift and glaciation in the Sierra de Gredos has exposed many of these plutonic and metamorphic rocks, revealing excellent outcrops that provide opportunities to observe world-class examples of magmatic processes at the emplacement level. The study of field relations in outcrops such as the Gredos massif has enabled an in-depth discussion on the origin of magmatic fabrics and structures, the observation of the variety of enclave types and how these contribute to a deeper understanding of petrogenetic and rheological aspects, as well as a more precise interpretation of the interaction (assimilation) processes between intrusive magmas and the host metasediments. This work represents a journey into the crust where all these magmatic processes occurred, highlighting their main characteristics based on field relationships and supported by geochemical, petrological, structural, experimental, and geochronological evidence.