Pliocene endorheic-exhoreic drainage transition of the Cenozoic Madrid Basin (Central Spain)

Abstract

Late Cenozoic landscape evolution in intracratonic basins represents an illustrative example of the interaction between surface processes, climate, lithologic and tectonics factors. Here, we model the transition from endorheic to exorheic conditions for the intracratonic Madrid Basin (Tagus Basin, Central Spain). During the Late Cenozoic, this basin appears to have been the result of a prolonged period of ~4.0 Ma of headward erosion by the Atlantic external drainage system, local erosion and climatic oscillations. Determining the timing of this transition is crucial to understanding the principal mechanisms of the transition course of the intracratonic basins in or associated with pop-up ridges. We present a detailed geomorphic map of the north of the Tertiary Madrid basin and new age determinations of well-preserved pediments, alluvial fans, alluvial plains and strath terraces. By combining cosmogenic ˡ0Be-26Al-21Ne with magnetostratigraphic data, the sediments associated with the last endorheic phase yield an age of ~6.4 Ma. The earliest exorheic alluvial levels of the Madrid Cenozoic basin, explained here as the first fluvial terraces, have been dated through cosmogenic nuclides depth profiles (ˡ0Be-26Al) at 2.42 Ma and 2.36 Ma respectively.