Interplay between tectonics, climate, and fluvial transport during the Cenozoic evolution of the Ebro Basin (NE Iberia)

Abstract

Three‐dimensional modeling that integrates fluvial sediment transport, crustal‐scale tectonic deformation, and lithospheric flexural subsidence is carried out to simulate the landscape and drainage evolution of the Ebro sedimentary basin (NE Iberia). The Ebro Basin underwent a long period of closed intramountain drainage as a result of tectonic topography generation at the Pyrenees, the Iberian Range, and the Catalan Coastal Range. In the late Oligocene, the Catalan Coastal Range underwent extension leading to the formation of the Valencia Trough (NW Mediterranean), but the Ebro Basin remained closed for nearly 15 Myr more before the Ebro River cut through the remnants of the topographic barrier. This drainage opening caused widespread basin incision that shaped spectacular outcrops of the syntectonic and posttectonic infill. Here we investigate the processes controlling these major drainage changes. The modeling results, constrained by a large data set on the tectonic and transport evolution of the area, predict a closed phase characterized by a large lake in the central eastern Ebro Basin. Dry climatic conditions probably lowered the lake level and contributed, together with rift flank uplift, to prolong this endorheic basin stage. The age and amount of reworked sediment after the opening are consistent with an onset of basin incision between 13 and 8.5 Ma as a result of lake capture by escarpment erosion and lake level rise associated with sediment accumulation and wetter climatic conditions. Sea level changes in the Mediterranean had no major impact in the large‐scale drainage evolution of the Ebro Basin.

Exceptional river gorge formation from unexceptional floods

“…Overall, this study highlights several key observations concerning the morphological adjustment of bedrock rivers on Earth and Mars [50][51][52] that are particularly pertinent in the study of geomorphological phenomena such as extreme flood discharge events and river diversions through drainage capture and overspill: (1) that moderate water discharges (o1,500 m 3 s À 1 , in this example) are capable of radical erosion suggesting that adjustments to changes such as drainage diversion and capture may be initially much more rapid than has hereto been assumed 53,54 ; (2) that megafloods are not a prerequisite for major erosion events in mechanically strong lithologies; (3) that such radical erosion is strongly facilitated by a favourable discontinuity pattern in mechanically strong rocks even in the absence of significant surface weathering, and that this discontinuity pattern also strongly influences the gorge morphology; (4) that the key removal process in such rocks would appear to be fluvial plucking probably in association with block topple; (5) that spring sapping is not essential to develop an amphitheatre-headed gorge in resistant bedrock lithologies 1,4 ; and (6) that extreme erosion rates are possible even in the absence of bedload and suspended load. Furthermore, these observations have implications for the efficiency of bedrock erosion and raise important questions about incision rates, driving mechanisms and timescale assumptions for models of landscape evolution over a variety of temporal and spatial scales and for modern engineering strategies.…”

Forward modelling of the Bureba escarpment (Rioja Trough, N-Spain)

“…Paleozoic, Mesozoic and Cenozoic and 2. The overall transport is carried by surface waters, underground water flow is disgarded [2].…”

“…In this study I varied (1) elastic thickness, (2) river capacity and runoff, (3) diffusive erodability and (3) 2 (length×width) and its resolution is 1 km in both directions. The choice of rain=200 mm a −1 , i.e.…”

Quaternary alluvial sinkholes: Record of environmental conditions of karst development, examples from the Ebro Basin, Spain

“…This basin is bounded by the Iberian Range to the south and the Catalonian Coastal Range to the east, and is crossed by the Ebro River that flows towards the Mediterranean Sea to the east. The basin was endorheic from the Late Eocene to the MiddleLate Miocene (García-Castellanos et al, 2003) and alluvial fans sourced in the surrounding mountains interfered with central saline or carbonate lakes (Muñ oz et al, 2002;Pardo et al, 2004). Due to this paleogeographical distribution, the stratigraphic succession in the central part of the basin is characterized mainly by thick, nearly horizontal carbonate or evaporite rocks.…”