Mechanisms and age estimates of continental-scale endorheic to exorheic drainage transition: Douro River, Western Iberia

Pedro P. Cunha, António A. Martins, Alberto Gomes, Martin Stokes, João Cabral, Fernando C. Lopes, Diamantino Pereira, Gerardo de Vicente, Jan-Pieter Buylaert, Andrew S. Murray, Loreto Antón

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

In western Iberia, mechanisms that can explain the transition from endorheic to exorheic continental-scale drainage reorganization are foreland basin overspill, headwards erosion and capture by an Atlantic river, or a combination of both. To explore these, we have investigated the Portuguese sector of the Douro River, the locus of drainage reorganization. The Douro River is routed downstream through the weak sedimentary infill of the Douro Cenozoic Basin, after which the river cuts down through harder granitic and metamorphic rocks crossed by active fault zones, before reaching the Atlantic coast. We investigated the drainage reorganization using an integrated approach that combined remote sensing, field survey and geochronology, applied to Pliocene–Quaternary fluvial sediments and landforms. The older drainage record is documented by a series of high and intermediate landform levels comprising: (1) a high level (1000–500 m a.s.l.) faulted regional fluvial erosion surface, the North Iberian Meseta planation surface and the Mountains and Plateaus of Northern Portugal, recording the endorheic drainage of the Douro Cenozoic Basin; (2) a first inset level at 650–600 m a.s.l., comprising a broad fluvial surface developed onto a large ENE–WSW depression, interpreted as recording the initiation of the continental scale reorganization; and (3) an inset fluvial surface at 550–400 m a.s.l., corresponding to the establishment of the exorheic ancestral Douro valley. The younger drainage record comprises an entrenched fluvial strath terrace sequence of up to 9 levels (T9 = oldest), positioned at 246–242 m above the modern river base; T1 = youngest, positioned at +17–13 m. Levels T1 and T3 display localized fault offsets. The three lowest terrace levels (T3–T1) were dated using optically stimulated luminescence techniques with results ranging from >230–360 ka (T3), through 57 ka (T2) to 39–12 ka (T1). Fluvial incision rates of the younger terraces were quantified and temporally extrapolated to model the ages of the intermediate to high elevation levels of the early drainage record. Integration of incision data informs on the probable timing of the drainage reorganization and the initial adjustment, ~3.7–1.8 Ma. This was followed by acceleration of incision, producing the entrenched river terrace sequence developed via spatial and temporal variations in rock strength, uplift and cyclic cool-climate variability as the river adjusted to the Atlantic base level.
Original languageEnglish
Article number102985
JournalGlobal and Planetary Change
Volume181
Number of pages20
ISSN0921-8181
DOIs
Publication statusPublished - 2019

Keywords

  • Western Iberia
  • Transverse drainage
  • Basin overspill
  • Incision rate
  • Terrace staircase
  • Luminescence dating

Cite this

Cunha, Pedro P. ; Martins, António A. ; Gomes, Alberto ; Stokes, Martin ; Cabral, João ; Lopes, Fernando C. ; Pereira, Diamantino ; de Vicente, Gerardo ; Buylaert, Jan-Pieter ; Murray, Andrew S. ; Antón, Loreto. / Mechanisms and age estimates of continental-scale endorheic to exorheic drainage transition: Douro River, Western Iberia. In: Global and Planetary Change. 2019 ; Vol. 181.
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title = "Mechanisms and age estimates of continental-scale endorheic to exorheic drainage transition: Douro River, Western Iberia",
abstract = "In western Iberia, mechanisms that can explain the transition from endorheic to exorheic continental-scale drainage reorganization are foreland basin overspill, headwards erosion and capture by an Atlantic river, or a combination of both. To explore these, we have investigated the Portuguese sector of the Douro River, the locus of drainage reorganization. The Douro River is routed downstream through the weak sedimentary infill of the Douro Cenozoic Basin, after which the river cuts down through harder granitic and metamorphic rocks crossed by active fault zones, before reaching the Atlantic coast. We investigated the drainage reorganization using an integrated approach that combined remote sensing, field survey and geochronology, applied to Pliocene–Quaternary fluvial sediments and landforms. The older drainage record is documented by a series of high and intermediate landform levels comprising: (1) a high level (1000–500 m a.s.l.) faulted regional fluvial erosion surface, the North Iberian Meseta planation surface and the Mountains and Plateaus of Northern Portugal, recording the endorheic drainage of the Douro Cenozoic Basin; (2) a first inset level at 650–600 m a.s.l., comprising a broad fluvial surface developed onto a large ENE–WSW depression, interpreted as recording the initiation of the continental scale reorganization; and (3) an inset fluvial surface at 550–400 m a.s.l., corresponding to the establishment of the exorheic ancestral Douro valley. The younger drainage record comprises an entrenched fluvial strath terrace sequence of up to 9 levels (T9 = oldest), positioned at 246–242 m above the modern river base; T1 = youngest, positioned at +17–13 m. Levels T1 and T3 display localized fault offsets. The three lowest terrace levels (T3–T1) were dated using optically stimulated luminescence techniques with results ranging from >230–360 ka (T3), through 57 ka (T2) to 39–12 ka (T1). Fluvial incision rates of the younger terraces were quantified and temporally extrapolated to model the ages of the intermediate to high elevation levels of the early drainage record. Integration of incision data informs on the probable timing of the drainage reorganization and the initial adjustment, ~3.7–1.8 Ma. This was followed by acceleration of incision, producing the entrenched river terrace sequence developed via spatial and temporal variations in rock strength, uplift and cyclic cool-climate variability as the river adjusted to the Atlantic base level.",
keywords = "Western Iberia, Transverse drainage, Basin overspill, Incision rate, Terrace staircase, Luminescence dating",
author = "Cunha, {Pedro P.} and Martins, {Ant{\'o}nio A.} and Alberto Gomes and Martin Stokes and Jo{\~a}o Cabral and Lopes, {Fernando C.} and Diamantino Pereira and {de Vicente}, Gerardo and Jan-Pieter Buylaert and Murray, {Andrew S.} and Loreto Ant{\'o}n",
year = "2019",
doi = "10.1016/j.gloplacha.2019.102985",
language = "English",
volume = "181",
journal = "Global and Planetary Change",
issn = "0921-8181",
publisher = "Elsevier",

}

Cunha, PP, Martins, AA, Gomes, A, Stokes, M, Cabral, J, Lopes, FC, Pereira, D, de Vicente, G, Buylaert, J-P, Murray, AS & Antón, L 2019, 'Mechanisms and age estimates of continental-scale endorheic to exorheic drainage transition: Douro River, Western Iberia', Global and Planetary Change, vol. 181, 102985. https://doi.org/10.1016/j.gloplacha.2019.102985

Mechanisms and age estimates of continental-scale endorheic to exorheic drainage transition: Douro River, Western Iberia. / Cunha, Pedro P.; Martins, António A.; Gomes, Alberto; Stokes, Martin; Cabral, João; Lopes, Fernando C.; Pereira, Diamantino; de Vicente, Gerardo; Buylaert, Jan-Pieter; Murray, Andrew S.; Antón, Loreto.

In: Global and Planetary Change, Vol. 181, 102985, 2019.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Mechanisms and age estimates of continental-scale endorheic to exorheic drainage transition: Douro River, Western Iberia

AU - Cunha, Pedro P.

AU - Martins, António A.

AU - Gomes, Alberto

AU - Stokes, Martin

AU - Cabral, João

AU - Lopes, Fernando C.

AU - Pereira, Diamantino

AU - de Vicente, Gerardo

AU - Buylaert, Jan-Pieter

AU - Murray, Andrew S.

AU - Antón, Loreto

PY - 2019

Y1 - 2019

N2 - In western Iberia, mechanisms that can explain the transition from endorheic to exorheic continental-scale drainage reorganization are foreland basin overspill, headwards erosion and capture by an Atlantic river, or a combination of both. To explore these, we have investigated the Portuguese sector of the Douro River, the locus of drainage reorganization. The Douro River is routed downstream through the weak sedimentary infill of the Douro Cenozoic Basin, after which the river cuts down through harder granitic and metamorphic rocks crossed by active fault zones, before reaching the Atlantic coast. We investigated the drainage reorganization using an integrated approach that combined remote sensing, field survey and geochronology, applied to Pliocene–Quaternary fluvial sediments and landforms. The older drainage record is documented by a series of high and intermediate landform levels comprising: (1) a high level (1000–500 m a.s.l.) faulted regional fluvial erosion surface, the North Iberian Meseta planation surface and the Mountains and Plateaus of Northern Portugal, recording the endorheic drainage of the Douro Cenozoic Basin; (2) a first inset level at 650–600 m a.s.l., comprising a broad fluvial surface developed onto a large ENE–WSW depression, interpreted as recording the initiation of the continental scale reorganization; and (3) an inset fluvial surface at 550–400 m a.s.l., corresponding to the establishment of the exorheic ancestral Douro valley. The younger drainage record comprises an entrenched fluvial strath terrace sequence of up to 9 levels (T9 = oldest), positioned at 246–242 m above the modern river base; T1 = youngest, positioned at +17–13 m. Levels T1 and T3 display localized fault offsets. The three lowest terrace levels (T3–T1) were dated using optically stimulated luminescence techniques with results ranging from >230–360 ka (T3), through 57 ka (T2) to 39–12 ka (T1). Fluvial incision rates of the younger terraces were quantified and temporally extrapolated to model the ages of the intermediate to high elevation levels of the early drainage record. Integration of incision data informs on the probable timing of the drainage reorganization and the initial adjustment, ~3.7–1.8 Ma. This was followed by acceleration of incision, producing the entrenched river terrace sequence developed via spatial and temporal variations in rock strength, uplift and cyclic cool-climate variability as the river adjusted to the Atlantic base level.

AB - In western Iberia, mechanisms that can explain the transition from endorheic to exorheic continental-scale drainage reorganization are foreland basin overspill, headwards erosion and capture by an Atlantic river, or a combination of both. To explore these, we have investigated the Portuguese sector of the Douro River, the locus of drainage reorganization. The Douro River is routed downstream through the weak sedimentary infill of the Douro Cenozoic Basin, after which the river cuts down through harder granitic and metamorphic rocks crossed by active fault zones, before reaching the Atlantic coast. We investigated the drainage reorganization using an integrated approach that combined remote sensing, field survey and geochronology, applied to Pliocene–Quaternary fluvial sediments and landforms. The older drainage record is documented by a series of high and intermediate landform levels comprising: (1) a high level (1000–500 m a.s.l.) faulted regional fluvial erosion surface, the North Iberian Meseta planation surface and the Mountains and Plateaus of Northern Portugal, recording the endorheic drainage of the Douro Cenozoic Basin; (2) a first inset level at 650–600 m a.s.l., comprising a broad fluvial surface developed onto a large ENE–WSW depression, interpreted as recording the initiation of the continental scale reorganization; and (3) an inset fluvial surface at 550–400 m a.s.l., corresponding to the establishment of the exorheic ancestral Douro valley. The younger drainage record comprises an entrenched fluvial strath terrace sequence of up to 9 levels (T9 = oldest), positioned at 246–242 m above the modern river base; T1 = youngest, positioned at +17–13 m. Levels T1 and T3 display localized fault offsets. The three lowest terrace levels (T3–T1) were dated using optically stimulated luminescence techniques with results ranging from >230–360 ka (T3), through 57 ka (T2) to 39–12 ka (T1). Fluvial incision rates of the younger terraces were quantified and temporally extrapolated to model the ages of the intermediate to high elevation levels of the early drainage record. Integration of incision data informs on the probable timing of the drainage reorganization and the initial adjustment, ~3.7–1.8 Ma. This was followed by acceleration of incision, producing the entrenched river terrace sequence developed via spatial and temporal variations in rock strength, uplift and cyclic cool-climate variability as the river adjusted to the Atlantic base level.

KW - Western Iberia

KW - Transverse drainage

KW - Basin overspill

KW - Incision rate

KW - Terrace staircase

KW - Luminescence dating

U2 - 10.1016/j.gloplacha.2019.102985

DO - 10.1016/j.gloplacha.2019.102985

M3 - Journal article

VL - 181

JO - Global and Planetary Change

JF - Global and Planetary Change

SN - 0921-8181

M1 - 102985

ER -