Reactivation of early reverse faults associated with oblique strike-slip faulting: a mechanism for crustal shortening (Macizo de Nevera, Sierra de Albarracín, Spain)

Abstract

Detailed structural and lithological analysis in the Macizo de Nevera, Spain, has revealed that the structure of the Palaeozoic basement rocks is much more complex than hitherto recognized. Alternations of pelite and psammite, separated by distinct thin intervals of orthoquartzite, are folded around shallow north-plunging fold axes. Detailed mapping of these folds disclosed that the synforms are consistently excised by reverse faulting along strike. In the western part of the Macizo de Nevera, this essentially simple structure is seriously complicated by a NE-SW trending system of en-echelon arranged dextral strike-slip faults, that partly reactivated the earlier reverse faults. Due to reworking of the latter faults, the crustal section was further shortened in an E-W direction, the motion being mainly concentrated on faults on either side of the Vallejo Hondo Anticline. Neither of the fault generations discussed continue into the Mesozoic cover of Triassic and Jurassic sediments which surrounds the Macizo. In an appendix to the paper, the Palaeozoic rock units are described.