Granite emplacement in orogenic compressional conditions: the La Alberca-Bejar granitic area (Spanish Central System, Variscan Iberian Belt)

The La Alberca-Bejar granitic area comprises a set of intrusions of Upper C arboniferous to Lower Permian age located in the hinterland of the Variscan belt of western Spain. Gravity data, anisotropy of magnetic susceptibility , and microstructural studies carried out in the granitoid and its country rocks indicate that the granitoids of this region have tabular and inverted drop shapes and show sub-horizontal magmatic fabrics and SW-NE lineations. The granitoid bodies were intruded episodically, with single intrusive pul ses recorded by deformation in the country rocks. All intrusive events took place during D-3 compressive stage, in the core of large D-1 anticlines, a nd are not related to structures in the country rock. A syn-orogenic emplac ement model for granite intrusion in such conditions is proposed. The propo sed model implies the activity of coeval emplacement mechanisms and room ge neration. (C) 1999 Elsevier Science Ltd. All rights reserved.