Estructura interna del batolito granítico de Nisa-Alburquerque

Resumen

The Late Variscan Nisa-Alburquerque batholith (SW-Iberian Peninsula) is located close to the boundary between two major geologic domains of the Iberian Massif: the Central Iberian Zone and the Ossa-Morena Zone. This baholith is made up of S-type granitic rocks with minor I-type ones. The main facies displays frequent magmatic orientations defined by the k-feldspar ± plagioclase phenocrysts. We have made six schematic cross sections perpendicular to the internal structure and to the elongated shape of the batholith. These sections show the internal structure of the batholith and the relationships between the different granitic facies. The cross-cutting relationships indicate that the general orientation was developed during the emplacement of the main granitic magma and prior to the differentiation/intrusion of the remaining facies. Diachronic eastward-progressing cooling of the granitic magma could explain some of the differences between the western and central-eastern domains of the batholith: sharp contacts and fabric tightening in western domains versus sinuous contacts, magma mixing and re-intrusion of different magmas, in central-eastern domains.