Petrology, magnetic fabric and emplacement in a strike-slip regime of a zoned peraluminous granite: the Campanario-La Haba pluton, Spain

Abstract

AbstractThis paper reports field, petrological and structural data of the peraluminous cordierite-andalusite-bearing Campanario-La Haba granite. Crystallization age is constrained by Rb-Sr whole-rock dating at 309 ± 6 Ma (with (87Sr/86Sr)i = 0.70739 ± 0.00038) and took place during late Hercynian tectonic events. The pluton shows a petrographic zonation, although there are no marked differences in chemical compositions between the margin and the centre of the intrusion. Petrography, mineralogical data and geochemical modelling indicate melt generation by partial melting of a metasedimentary protolith, probably with some mantelic contribution as shown by its low Sri value, followed by emplacement at P < 3 kbar. The internal structure of the pluton resulted from the lateral spreading in the stretching direction given by an N120–130E dextral strike-slip zone and the external geometry seems to be strongly conditioned by faults (Riedel R type fractures) formed in the host rocks. This emplacement model agrees with that defined for the adjacent Extremadura granitic plutons and for the Los Pedroches batholith suggesting the existence of a dextral regional shear-zone in the South branch of the Central Iberian Zone.