THE INFLUENCE OF TECTONICS, SEA-LEVEL FLUCTUATIONS AND RIVER CAPTURE ON THE QUATERNARY MORPHOGENESIS OF THE SEMIARID PULPI BASIN (SOUTHEASTSPAIN)

The semi-arid Pulpi Basin is located within a 250km long left-lateral shear zone between Alicante and Almeria. The Pulpi Basin itself is cro ssed by the N20E-striking Palomares Fault, active during the Neogene a nd Quaternary. In the Upper Pliocene a major epeirogenic uplift occurr ed which caused emergence of the basins. Simultaneously, a change from marine to terrestrial sedimentation started and the development of th e present landscape began. The Quaternary relief development in the Pu lpi Basin has been particularly influenced by tectonic disturbances an d river captures, which have had contrasting effects on different part s of the basin. In the southern basin tectonically induced dissection of the oldest Quaternary glacis level was accompanied by the influence of the fluctuations in sea-level: both factors have caused continuing erosion. In the central Pulpi Basin Mid-Quaternary fluvial capture pr ocesses were important for the morphogenesis. Since the loss of the ca tchment areas in the neighbouring Huercal-Overa Basin the fluvial acti vity of the rivers in the western part has been Limited. The transitio n from the distal end of the Mid-Quaternary glacis to the present vall ey floor takes place without a noticeable step; no younger fluvial ter races are missing. In the eastern part, the catchment area of the main river has hardly changed since its establishment during the Upper Pli ocene. Besides the relies of the oldest glacis level no further glacis accumulation developed. During the Mid-Quaternary only a fluvial terr ace was deposited. (C) 1997 Elsevier Science B.V.