The Appinite-Migmatite Complex of Sanabria, NW Iberian Massif, Spain

Abstract

The Sanabria appinitic rocks and host migmatites form an unusual, non-peri-batholithic complex in which all the typical members of the appinite suite are present. It differs from most appinitic complexes in the deeper level of emplacement and the close temporal and spatial association with migmatites. Consequently, many in situ relationships that resulted from the invasion of mafic magma into a crustal anatectic zone are extremely well preserved. The complex shows unequivocal relations between members of the appinitic suite and between these and migmatites derived by anatexis of a gneissic formation (Ollo de Sapo gneiss). These relations point to derivation of monzodiorites and biotite diorites by hydrous basalt fractionation combined with fluid-assisted melting of the crustal rocks surrounding the appinitic intrusions. This hydrous basic magma may be derived from an enriched region of the mantle associated with subduction. Petrogenetic models have been tested using a combination of field relations and geochemical data. Despite the complexity of the processes involved, it is concluded that water played an important role in the petrogenesis of the intermediate and mafic magmas. Reaction between monzodiorite melts and the host migmatites was responsible for the generation of a range of intermediate rocks within the complex. The need for water to facilitate magma generation in both the mantle and the crust suggests that melting is linked with subduction. This interpretation has important implications because appinitic magmatism may be considered as indicative of subduction processes involved not only in the generation of the mafic end-members of the suite, but also in the generation of batholiths with which the appinitic rocks are spatially and temporally associated.

Geochemical characterization and isotopic age of Caradocian magmatism in the northeastern Iberian Peninsula: Insights into the Late Ordovician evolution of the northern Gondwana margin

“…Nd model ages (TOM) for most of the rocks are similar to those in samples from the Iberian massif (Femandez-Suarez et al, 2000;Castro et al, 2003;Rodrtguez Alonso et al, 2004;GuW�rrez Alonso et al, 2005;Murphy et al, 2008a). However, the strong crustal influence on the c;Nd values for felsic rocks rules out an unequivocal interpretation of the TOM ages.…”

Procedencia del material pétreo de los molinos de los yacimientos Cogotas I (Bronce Medio y Tardío) de la Cuenca del Duero y modelos consecuentes de flujo

“…Los leucogranitos del Sistema Central son realmente escasos (Villaseca et al, 1988) y se caracterizan por un menor contenido en moscovita, así como por la presencia de cordierita, granate o turmalina, minerales alumínicos ausentes en las muestras del presente estudio. Los leucogranitos del área de Sanabria se descartan porque son más ricos en CaO (0,8-1,1 % frente a 0,54-0,71) y en Sr (157-163 ppm frente a 29-72 ppm) y más pobres en P 2 O 5 (0,10-0,30 % frente a 0,37-0,48 %), de acuerdo con los datos de Castro et al (2003).…”

“…A este respecto, las rocas granodioríticas del Batolito de Sayago muestran valores frecuentemente superiores a 300 ppm tanto en ΣREE como en Zr, en contraste con las granodioritas de Sanabria, que apenas sobrepasan 200 ppm en REE y 150 ppm en Zr (Castro et al, 2003), y aún con mayor contraste, las rocas granodioríticas de todo el borde septentrional del Sistema Central, con valores por lo general muy inferiores a 200 ppm (Villaseca & Herreros, 2000). Dado que la muestra DPC2 contiene valores de ΣREE de 416 ppm y Zr de 350 ppm (Tabla 3A), es oportuno descartar las áreas de Sanabria y del Sistema Central como áreas fuente potenciales.…”

“…Estudios Geológicos, 74(1), enero-junio 2018, e074, ISSN-L: 0367-0449. http://doi.org/10.3989/egeol.42955.462 las biotitas del Batolito de Sayago, pero está por encima del valor característico de las granodioritas de Sanabria, que es de 0,3 (Castro et al, 2003).…”

Origines des enrichissements en biotite dans les granites de type S :

“…Un certain nombre d'hypothèses ont été avancées comme le mélange de magma de compositions différentes (Barnes et al, 2002;Castro et al, 2003;Clemens, 2002;Collins et aL, 1989;Collins and Sawyer, 1996;Garcia-Moreno et al, 2007;Stevens et aL, 2007;Ugidos and Recio, 1993;White and Chappell, 1977), l'assimilation de roches encaissantes durant le transport et la mise en place du magma, et plus récemment Pentrainement de phases péritectiques lors de l'extraction du liquide (Collins and Sawyer, 1996;Dorais et al, 2009;Erdmann et al, 2009;Miller et aL, 1988;Sawyer, 1996;Stevens et aL, 2007;Villaros et al, 2009) SiO 2 (wt.%) 76 80…”