Geomorphic and tectonic implications of the endorheic to exorheic transition of the Ebro River system in northeast Iberia

Abstract

The Ebro catchment includes a continental foreland basin that underwent an endorheic–exorheic transition. Morphometric studies, including hypsometric curves, hypsometric integrals, asymmetry factor, mountain front sinuosity, normalised stream-length gradient, and normalised concavity indices for the Ebro River and 32 of its tributaries, show the signals of transient response to this major drainage change. The Ebro River, its upper catchment tributaries, and the Pyrenean tributaries have concave-up longitudinal profiles, concave hypsometric curves, and low hypsometric integrals, parameters typical of deeply dissected basins. This suggests a mature stage of development, controlled by the shift of the base level to the Mediterranean Sea. Iberian Range tributaries display low concavity profiles with numerous knickpoints and high values of hypsometric integral, indicating a transient state as a response to tectonic uplift, ratified by the values of mountain front sinuosity surrounding the basin.

A celebration of the twentieth anniversary of the Fluvial Archives Group (FLAG)

“…There is still some debate about the age of the transition, either before or after the Messinian. Soria-Jáureguia et al (2018, this thematic set) show that the Ebro and the Pyrenean tributaries are at a mature stage of development, which seems to agree with a Tortonian or Messinian age of the transition. The tributaries in the south are still in a transient state.…”

“…In addition, the authors use the comparison of reconstructed denudation rates with other systems to suggest an age of <3 Ma for basin opening, an event that is otherwise chronologically unconstrained. Similarly, Soria-Jauregui et al (2018, this thematic set) use geomorphic indices (focus 2.2) to study the impact of the endo- to exhorheic transition of the Ebro basin in Spain on the subsequent Ebro river system. There is still some debate about the age of the transition, either before or after the Messinian.…”

“…This selection of papers shows that research into fluvial archives over multiple temporal and spatial scales is now routinely applying techniques such as GIS, geophysics, and OSL dating, once considered to be new. GIS allows researchers to broaden their spatial scale away from the site-based study to multiple reaches (e.g., Mandarino et al, 2018, this thematic set; Woolderink et al, 2018, this thematic set) or whole basins (e.g., Anton and Martin, 2018, this thematic set; Soria-Jáureguia et al, 2018, this thematic set), whilst geophysical techniques can improve stratigraphic certainty at a site scale (e.g., Niebieszczański et al, 2018, this thematic set). OSL dating has been crucial in understanding river activity beyond the radiocarbon limit, particularly allowing phases of deposition to be more decisively linked to the climate record (e.g., Avsin et al, 2019, this thematic set; Wang et al, 2018, this thematic set), providing insight into fluvial processes and sometimes overturning previous assumptions (e.g., Olszak et al, 2018, this thematic set).…”

Estudio de la evolución cuaternaria de un modelado fluvial escalonado intramontañoso mediante índices morfométricos: río Lozoya, Sistema Central Español

“…Along these lines, many studies of the Quaternary landscape evolution of the internal basins of the Iberian Peninsula have been carried out (Silva et al, 1988;Pérez-González, 1994;García-Castellanos et al, 2003;Benito-Calvo & Pérez-González, 2008;Cunha et al, 2008;Benito-Calvo & Pérez-González, 2010;Antón et al, 2012;García-Castellanos & Larrasoaña, 2015;Silva et al, 2017;Soria-Jáuregui et al, 2018;Cunha et al, 2019;Struth et al, 2019;Gouveia et al, 2020;Rodríguez-Rodríguez et al, 2020). Likewise, this paper analyzes the Quaternary landscape geometry and evolution of the Lozoya intramountain basin located in the eastern part of the Spanish Central System (SCS), which presents a complex morphostructural evolution (Figure 1; Hernández-Pacheco 1932;Schwenzner, 1937;Birot & Solè Sabaris, 1954;Gladfelter, 1971;Pedraza, 1978;Garzón Heydt, 1980;Gracia et al, 1988;Pérez-González, 1994;Gutiérrez-Elorza & Gracia, 1997;Silva & Ortiz, 2002;Alonso-Zarza et al, 1993;Vicente et al, 2007;Benito Calvo & Pérez-González, 2010;Vicente et al, 2011;Karampaglidis, 2015;Silva et al, 2017;Karampaglidis et al, 2020).…”

“…To contribute to these questions, we carried out a detailed geomorphological study applying geomorphometric indices. Using these indices and geomorphological analysis to study uplift processes, incision, lithostructural controls, climatic events or fluvial captures is a technique that has been applied successfully for years in landscape evolution studies (Horton, 1945;Strahler, 1964;Hack, 1973;Bull & McFadden, 1977;Garzón Heydt, 1980;Silva et al, 1988;Ritter et al, 1995;Garrote et al, 2002;McKnight & Hess, 2005;Garrote et al, 2008;Türkan & Bekir, 2011;Antón et al, 2014;Soria-Jáuregui et al, 2018). Terrain evolution is thought to converge towards a dynamic equilibrium between uplift and incision (Burbank & Anderson, 2001).…”