CRUSTAL DECOUPLING AND INTRACRUSTAL FLOW BENEATH DOMAL EXHUMED CORE COMPLEXES, BETICS (SE SPAIN)

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 co re-bounding detachment system formed during the Serravallian (15-11 Ma ) in an episode of ENE-WSW extension. The ESCI-Beticas 2 deep seismic reflection profile, a transect through the core, shows a highly reflec tive deep crust overlying a subhorizontal Moho, and a fairly transpare nt upper crust and upper mantle. The lack of Moho relief beneath this area, with differential values for supracrustal thinning, suggests a m echanism of intracrustal isostatic compensation. Surface geology data together with seismic imaging indicate intracrustal flow and upward do ming as a response to footwall unloading accompanying the middle Mioce ne supracrustal extension. A prominent mid-crustal reflector (MCR) is deemed to represent a decoupling zone between the upper and the deep c rust. Subsequent N-S shortening and associated folding occurred in the late Miocene. The interference pattern of this folding over the middl e Miocene core produced the current E-W dome-shaped tectonic windows w here the deepest complex of the Betic hinterland crops out.