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Compresión NNW -SSE tardi a postmetamórfica y extensión subordinada en el Complejo Alpujárride (Dominio de Alborán, Orógeno Bético)

1993; Volume: 6; Issue: 1 Linguagem: Inglês

José Fernando Simancas Cabrera, Joaquín Campos,

Archaeological and Geological Studies

The evolution of the Alboran Domain in the Betic Orogen is complex, with diffeient vectors oftectonic translation and with contractional and extensional episodes. Work on extensional tectonics has been particularly outstanding in the last years, leading to the reinterpretation of sorne contacts previously considered as thmsts. Nevertheless, recent proposals that the reorganization towards the NINNW in the Alpujarride Complex (a fundamental Unit ofthe Alboran Domain) is a extensional episode are not adequately supported, as we discuss in this paper. We describe the structure of a large sector of the Alpujarride Complex and show that :1) there are late-metamorphic folds overtumed towards the NNW, developed on a rock-layering having generally a faint slope towards the W; 2) the folds are cut in a complex manner by a brittle shear system with top to the N/NNW movement; sorne geometries of this system are extensional but others are typical of thmsting. The shear system organizes the Alpujarride Complex in a number of tectonic slices each one being a repetition (more or less complete) of the lithologic sequence and the metamorphic zonation. From the very existence of the folds, the geometrical analysis offolds and shears, the late-metamorphic character of the folds and the repetitions of the metamorphic zonation in the building of tectonic slices, we conclude that the late to postrnetamorphic reorganization towards the NINNW is essentially a contractional episode. Finally, the place of this episode in the general evolution of the Alpujarride Complex is discussed. A complex evolution implying altemating episodes of dominant contraction and dominant extension is needed to integrate the available data.