QUANTIFICATION OF FLUVIAL INCISION OF DOURO RIVER TRIBUTARIES (NE PORTUGAL) - BASE LEVEL, DIFFERENTIAL UPLIFT AND LITHOLOGICAL CONTROLS ON THE RIVERS LONG PROFILE EVOLUTION

Detalhes bibliográficos
Autor(a) principal: Martins, António
Data de Publicação: 2014
Outros Autores: Gomes, António, Cunha, Pedro, Cabral, João
Tipo de documento: Artigo de conferência
Idioma: por
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/10174/13511
Resumo: This study analyses the long profiles of the Águeda, Côa, Távora and Paiva rivers, and of other Douro River lower order tributaries. The Águeda and Côa rivers flow encased on the vast planation surface that characterizes the Hesperian Massif morphology (the Iberian Meseta), while the Távora and Paiva rivers flow through higher, uplifted blocks, located west of the Vilariça fault zone (VFZ). These streams flow through a landscape strongly influenced by variations in bedrock lithology (granites and metasediments), fault structures that promoted differential uplift, and significant base-level changes. The longitudinal profiles of the Douro tributaries commonly display concavities separated by knickpoints/knickzones. The most upstream concavity reflects a relict graded profile of probable Piacenzian – Gelasian age, testifying an Atlantic exoreic drainage coeval of a high sea-level. Downstream concavities reflect the on-going transmission of several incision waves, linked to the Pleistocene - present stage of fluvial incision. In downstream concavities, the stream is graded to transient forms of the river profile with respect to the lithology, structure and base level history. They alternate with convexities (knickzones) developed where the incision waves were delayed, pinned to granite contacts. The amount of incision that postdates the relict graded profile, obtained by downstream extrapolation of the relict concave reach to the confluence with the trunk river, varies from ca. 400-450 m in the Iberian Meseta (east of the VFZ) to more than 600-650 m in the more uplifted blocks at the west. However, east of the VFZ, the amount of incision inferred by this procedure overestimates the incision measured from the surface of Meseta which is here located below the extrapolated relict long profiles by an amount that reaches ca. 120 m at the River Côa mouth. This overestimation supports: a) a northwards tilting of the Iberia Meseta in this area since the Late Miocene; b) the differential uplift along the VFZ, resulting from a northwards increase of the relative downthrowing of the eastern block of this fault; c) the exhumation of the Iberian Meseta by removal of a Cenozoic cover, whose thickness would be equivalent to the difference in height between the projected relict profile and the Meseta surface. The larger incision (525 and 477 m) inferred at the Águeda and Aguiar stream mouths is associated with long term enhanced uplift of the Iberian Meseta. For the last ca. 2 Ma (beginning of the incision stage?) incision rates can range from 0.2 mm/yr in the less uplifted compartments to 0.6 mm/yr in the more uplifted blocks (west of the VFZ). This work is in the scope of proj. PTDC/GEO-GEO/2860/2012
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spelling QUANTIFICATION OF FLUVIAL INCISION OF DOURO RIVER TRIBUTARIES (NE PORTUGAL) - BASE LEVEL, DIFFERENTIAL UPLIFT AND LITHOLOGICAL CONTROLS ON THE RIVERS LONG PROFILE EVOLUTIONFLUVIAL INCISIONDOURODIFFERENTIAL UPLIFTLITHOLOGICAL CONTROLSThis study analyses the long profiles of the Águeda, Côa, Távora and Paiva rivers, and of other Douro River lower order tributaries. The Águeda and Côa rivers flow encased on the vast planation surface that characterizes the Hesperian Massif morphology (the Iberian Meseta), while the Távora and Paiva rivers flow through higher, uplifted blocks, located west of the Vilariça fault zone (VFZ). These streams flow through a landscape strongly influenced by variations in bedrock lithology (granites and metasediments), fault structures that promoted differential uplift, and significant base-level changes. The longitudinal profiles of the Douro tributaries commonly display concavities separated by knickpoints/knickzones. The most upstream concavity reflects a relict graded profile of probable Piacenzian – Gelasian age, testifying an Atlantic exoreic drainage coeval of a high sea-level. Downstream concavities reflect the on-going transmission of several incision waves, linked to the Pleistocene - present stage of fluvial incision. In downstream concavities, the stream is graded to transient forms of the river profile with respect to the lithology, structure and base level history. They alternate with convexities (knickzones) developed where the incision waves were delayed, pinned to granite contacts. The amount of incision that postdates the relict graded profile, obtained by downstream extrapolation of the relict concave reach to the confluence with the trunk river, varies from ca. 400-450 m in the Iberian Meseta (east of the VFZ) to more than 600-650 m in the more uplifted blocks at the west. However, east of the VFZ, the amount of incision inferred by this procedure overestimates the incision measured from the surface of Meseta which is here located below the extrapolated relict long profiles by an amount that reaches ca. 120 m at the River Côa mouth. This overestimation supports: a) a northwards tilting of the Iberia Meseta in this area since the Late Miocene; b) the differential uplift along the VFZ, resulting from a northwards increase of the relative downthrowing of the eastern block of this fault; c) the exhumation of the Iberian Meseta by removal of a Cenozoic cover, whose thickness would be equivalent to the difference in height between the projected relict profile and the Meseta surface. The larger incision (525 and 477 m) inferred at the Águeda and Aguiar stream mouths is associated with long term enhanced uplift of the Iberian Meseta. For the last ca. 2 Ma (beginning of the incision stage?) incision rates can range from 0.2 mm/yr in the less uplifted compartments to 0.6 mm/yr in the more uplifted blocks (west of the VFZ). This work is in the scope of proj. PTDC/GEO-GEO/2860/2012Fluvial Archive Group (FLAG)2015-03-23T14:34:26Z2015-03-232014-09-02T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/conferenceObjecthttp://hdl.handle.net/10174/13511http://hdl.handle.net/10174/13511porsimnaonaoaam@uevora.ptndndndMartins, AntónioGomes, AntónioCunha, PedroCabral, Joãoinfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2024-01-03T18:58:57Zoai:dspace.uevora.pt:10174/13511Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-20T01:06:54.541850Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv QUANTIFICATION OF FLUVIAL INCISION OF DOURO RIVER TRIBUTARIES (NE PORTUGAL) - BASE LEVEL, DIFFERENTIAL UPLIFT AND LITHOLOGICAL CONTROLS ON THE RIVERS LONG PROFILE EVOLUTION
title QUANTIFICATION OF FLUVIAL INCISION OF DOURO RIVER TRIBUTARIES (NE PORTUGAL) - BASE LEVEL, DIFFERENTIAL UPLIFT AND LITHOLOGICAL CONTROLS ON THE RIVERS LONG PROFILE EVOLUTION
spellingShingle QUANTIFICATION OF FLUVIAL INCISION OF DOURO RIVER TRIBUTARIES (NE PORTUGAL) - BASE LEVEL, DIFFERENTIAL UPLIFT AND LITHOLOGICAL CONTROLS ON THE RIVERS LONG PROFILE EVOLUTION
Martins, António
FLUVIAL INCISION
DOURO
DIFFERENTIAL UPLIFT
LITHOLOGICAL CONTROLS
title_short QUANTIFICATION OF FLUVIAL INCISION OF DOURO RIVER TRIBUTARIES (NE PORTUGAL) - BASE LEVEL, DIFFERENTIAL UPLIFT AND LITHOLOGICAL CONTROLS ON THE RIVERS LONG PROFILE EVOLUTION
title_full QUANTIFICATION OF FLUVIAL INCISION OF DOURO RIVER TRIBUTARIES (NE PORTUGAL) - BASE LEVEL, DIFFERENTIAL UPLIFT AND LITHOLOGICAL CONTROLS ON THE RIVERS LONG PROFILE EVOLUTION
title_fullStr QUANTIFICATION OF FLUVIAL INCISION OF DOURO RIVER TRIBUTARIES (NE PORTUGAL) - BASE LEVEL, DIFFERENTIAL UPLIFT AND LITHOLOGICAL CONTROLS ON THE RIVERS LONG PROFILE EVOLUTION
title_full_unstemmed QUANTIFICATION OF FLUVIAL INCISION OF DOURO RIVER TRIBUTARIES (NE PORTUGAL) - BASE LEVEL, DIFFERENTIAL UPLIFT AND LITHOLOGICAL CONTROLS ON THE RIVERS LONG PROFILE EVOLUTION
title_sort QUANTIFICATION OF FLUVIAL INCISION OF DOURO RIVER TRIBUTARIES (NE PORTUGAL) - BASE LEVEL, DIFFERENTIAL UPLIFT AND LITHOLOGICAL CONTROLS ON THE RIVERS LONG PROFILE EVOLUTION
author Martins, António
author_facet Martins, António
Gomes, António
Cunha, Pedro
Cabral, João
author_role author
author2 Gomes, António
Cunha, Pedro
Cabral, João
author2_role author
author
author
dc.contributor.author.fl_str_mv Martins, António
Gomes, António
Cunha, Pedro
Cabral, João
dc.subject.por.fl_str_mv FLUVIAL INCISION
DOURO
DIFFERENTIAL UPLIFT
LITHOLOGICAL CONTROLS
topic FLUVIAL INCISION
DOURO
DIFFERENTIAL UPLIFT
LITHOLOGICAL CONTROLS
description This study analyses the long profiles of the Águeda, Côa, Távora and Paiva rivers, and of other Douro River lower order tributaries. The Águeda and Côa rivers flow encased on the vast planation surface that characterizes the Hesperian Massif morphology (the Iberian Meseta), while the Távora and Paiva rivers flow through higher, uplifted blocks, located west of the Vilariça fault zone (VFZ). These streams flow through a landscape strongly influenced by variations in bedrock lithology (granites and metasediments), fault structures that promoted differential uplift, and significant base-level changes. The longitudinal profiles of the Douro tributaries commonly display concavities separated by knickpoints/knickzones. The most upstream concavity reflects a relict graded profile of probable Piacenzian – Gelasian age, testifying an Atlantic exoreic drainage coeval of a high sea-level. Downstream concavities reflect the on-going transmission of several incision waves, linked to the Pleistocene - present stage of fluvial incision. In downstream concavities, the stream is graded to transient forms of the river profile with respect to the lithology, structure and base level history. They alternate with convexities (knickzones) developed where the incision waves were delayed, pinned to granite contacts. The amount of incision that postdates the relict graded profile, obtained by downstream extrapolation of the relict concave reach to the confluence with the trunk river, varies from ca. 400-450 m in the Iberian Meseta (east of the VFZ) to more than 600-650 m in the more uplifted blocks at the west. However, east of the VFZ, the amount of incision inferred by this procedure overestimates the incision measured from the surface of Meseta which is here located below the extrapolated relict long profiles by an amount that reaches ca. 120 m at the River Côa mouth. This overestimation supports: a) a northwards tilting of the Iberia Meseta in this area since the Late Miocene; b) the differential uplift along the VFZ, resulting from a northwards increase of the relative downthrowing of the eastern block of this fault; c) the exhumation of the Iberian Meseta by removal of a Cenozoic cover, whose thickness would be equivalent to the difference in height between the projected relict profile and the Meseta surface. The larger incision (525 and 477 m) inferred at the Águeda and Aguiar stream mouths is associated with long term enhanced uplift of the Iberian Meseta. For the last ca. 2 Ma (beginning of the incision stage?) incision rates can range from 0.2 mm/yr in the less uplifted compartments to 0.6 mm/yr in the more uplifted blocks (west of the VFZ). This work is in the scope of proj. PTDC/GEO-GEO/2860/2012
publishDate 2014
dc.date.none.fl_str_mv 2014-09-02T00:00:00Z
2015-03-23T14:34:26Z
2015-03-23
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dc.publisher.none.fl_str_mv Fluvial Archive Group (FLAG)
publisher.none.fl_str_mv Fluvial Archive Group (FLAG)
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