From Extension to Transpression: Geomorphic Response to the Development of the Alhama de Murcia Strike-Slip Fault at a Morphotectonic Setting Inherited from Late Miocene Extension (Eastern Betics)
Marta Ferrater, Guillermo Booth-Rea, José Miguel Azañón, José Vicente Pérez Peña, and Eulalia Masana
Drainage systems adapt to changes in the surface slope and thus have the potential to record the evolution of tectonic structures that produce surface uplift. The development of new mountain fronts can drive the abandonment of earlier drainage networks by way of fluvial captures. Here we analyze the evolution of topographical relief in a transcurrent tectonic setting where a relic drainage network inherited from late Miocene extension is still preserved. The recent drainage network is advancing thanks to tectonic driven rock uplift related to the Alhama de Murcia strike-slip fault and associated structures; overprinting the previous extensional related drainage. For this we carried out a structural and a qualitative and quantitative relief analysis to understand how the relief has evolved and which are the active structures that currently control the drainage configuration. We identify river capture sites and present a geomorphic index analysis using SLk anomalies, hypsometric curves, mountain front sinuosity, the comparison between longitudinal and projected river profiles with the SLk values and the position of active faults and folds, and a slope analysis of the area. This analysis mainly allows the understanding of the drainage network evolution. The results show 1) the reactivation of the ending part of the main basins by the current uplift of Tercia Range, 2) progressive capture processes related to the growth of the Rambla de Lebor and Totana transverse drainages upon a previous drainage pattern inherited from a late Miocene extensional setting evidenced by the presence of wind gaps, abrupt changes in flow direction, oblique relationship between current river direction and paleosurfaces maximum slope direction and changes in the lithologic composition of terraces, and 3) basin shapes controlled by the interference between a NE-SW-directed drainage network controlled by extensional structures and another NW-SE one controlled by transpressive structures (Alhama de Murcia Fault).
AAPG Search and Discovery Article #90161©2013 AAPG European Regional Conference, Barcelona, Spain, 8-10 April 2013