by

Martínez-Martínez, J. M.; Soto, J. I. and Balanyá, J. C.

Instituto Andaluz de Ciencias de la Tierra & Departamento de Geodinámica, C.S.I.C.-Universidad de Granada, Facultad de Ciencias, Campus Fuentenueva s/n, 18071-Granada, Spain.

Abstract

The Sierra Nevada core, located in the Betic hinterland, features a N-S large-scale open antiform with a central relatively uplifted highly extended domain placed between two less extended domains (in the east and in the west) dipping eastwards and westwards, respectively. The core-bounding detachment system formed during the Serravallian (15-11 Ma) in an episode of ENE-WSW extension. The ESCI-Béticas 2 deep seismic reflection profile, a transect through the core, shows a highly reflective deep crust overlying a subhorizontal Moho, and a fairly transparent upper crust and upper mantle. The lack of Moho relief beneath this area, with differential values for supracrustal thinning, suggests a mechanism of intracrustal isostatic compensation. Surface geology data together with seismic imaging indicate intracrustal flow and upward doming as a response to footwall unloading accompanying the middle Miocene supracrustal extension. A prominent mid-crustal reflector (MCR) is deemed to represent a decoupling zone between the upper and the deep crust. Subsequent N-S shortening and associated folding occurred in the late Miocene. The interference pattern of this folding over the middle Miocene core produced the current E-W dome-shaped tectonic windows where the deepest complex of the Betic hinterland crops out.

Terra Nova, 1997, vol. 9, 223-227.

Figure 1. Tectonic map of the Sierra Nevada and Sierra de los Filabres culminations, showing the Serravallian extensional detachment system and folds in the Sierra Nevada core.

Structural cross-section of the Sierra Nevada core parallel to the extension direction.

Figure 2. Crustal cross-section combining a line drawing of the ESCI-Béticas 2 profile and a structural section based on field data (detailed cross-section is shown first). Black circles indicate the position of the Vp change boundary reported by Banda et al. (1993) from two refraction profiles (PR1 and PR2) intersecting the ESCI-Béticas 2 profile. MCR: mid-crustal reflector; UCR: upper-crustal reflector. (Note that the cross-section above is the mirror image of the crustal section below.)

Main Page

Up Page