Tectonophysics, 171 (1990) 337-348 Elsevier Science Publishers B-V., Amsterdam - Printed in The Netherlands 337 Basement structure of the Granada basin, Betic Cordilleras, Southern Spain zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONM J. MORALES, F. VIDAL, F. DE MIGUEL, G. ALGUACIL, A.M. POSADAS, J.M. IBAtiEZ, A. GUZMAN and J.M. GUIRAO Obseruaiorio de Cartuja, Institute Andaluz de Geofisica y PrevenciLin de Desastres Sismicos, Universidad de Granada, 18071 -Granada, (Spain) (Received April 13,1989; revised version accepted November 6,1989) zyxwvutsrqponmlkjihgfedcbaZYXWVUT Abstract Morales, J., Vidal, F., De Miguel, F., Alguacil, G., Posades, A.M., Ibaiiez, J.M., Guman, A. and Guirao, J.M., 1990. Basement structure of the Granada basin, Betic Cordilleras, southern Spain. Tectonophysics, 177: 337-348. The analysis and interpretation of geophysical data (gravity and seismic reflection) has facilitated the definition of the Granada basin structure. The reflector showing the contact between the Betic-Subbetic basement and the Neogene-Quaternary sedimentary filling has been identified. Mapping of the basement in two and three dimensions is presented. The presence of four important depocenters (Genil, Chimeneas. Cubillas and Granada) has been de- termined. These troughs are limited by ridge areas through important sets of fractures. In some cases the aecumuiation of Neogene-Quatemary sediments reaches a thickness exceeding 3 km as in the Gem1 and Cubillas depocenters. The mapping of the most important fractures affecting the basement has been achieved, defining four systems that have influenced and conditioned the genesis and late evolution of the Granada basin. The directions of the most important groups of fractures are: NE-SW, N70W to E-W, N45W and NlO-30E. In~ ~ uction The Granada basin is located in the southeast of Spain. It has an average elevation of 700 m. Geographically the basin is limited by Sierra Nevada and Sierra A rana to the east; Tejeda, Alhama and Albuiiuelas Sierras to the south; Sierra Loja to the west and by the Subbetic ranges of Parapanda, Montefrlo and Moclin Sierras to the north (Fig. 1). The Granada basin is located in the central sector of the Betic Cordilleras; it is one of the larger intramountain Neogene basins of the Betic mountains. The Betic Cordilleras are the result of an in- tracontinental collision. The formation of the Betic Cordilleras occurred in various stages from the Late Cretaceous to the Neogene. The last Alpine event occurred appro~mately between the Late Oligocene and the middle Burdigalian, which al- most definitely formed the Betic Cordilleras. The deformation, however, continued during the Neogene and Quaternary generating the in- tramountain Neogene basins. The first features of the formation of the Granada basin started in the Middle Miocene, nevertheless it is from the Late Miocene (Early Tortonian) to the present that it acquired its prin- cipal characteristics. Geologically the Granada basin is bound to the north and west by Subbetic domain materials, mainly Jurassic and Cretaceous carbonate sedi- mentary series belonging to the Sudiberic paleomarge, and to the south and east by Alpujar- rides metamorphic units (schists, phyllites and quarzites of Palaeozoic and Triassic age and mar- 0040-1951/90/$03.50 0 1990 - Elsevier Science Publishers B.V.