Pliocene pedosedimentary cycles in the southern Pampas, Argentina

Autores
Kemp, R. A.; Zárate, Marcelo Arístides
Año de publicación
2000
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
Well-developed Bt horizons of five palaeosols (P1-P5) have been recorded previously within a 20-m-thick succession of Pliocene siltstones and clayey siltstones in the southern part of the Buenos Aires Province of Argentina. This paper reports a detailed field and micromorphological (thin section) investigation of a 6-m portion of the sequence encompassing P2 and P3. Large-scale faunal burrow infillings occur throughout: other bioturbation features in the form of channel and spongy microstructures are mainly confined to the siltstones. The intervening clayey siltstones (Bt horizons) have been affected more by shrink-swell disruption, as evidenced by slickensides and a range of striated b-fabrics in thin sections. Clay coatings, indicative of illuvial accumulation of clay translocated in suspension from overlying A or E horizons, occur in both the siltstones and clayey siltstones. The types, microstratigraphic associations and depth functions of features are interpreted in terms of changing interactions, balances and dominances between sedimentary, pedogenic and erosional processes over time, thus providing the basis for the pedosedimentary reconstruction of landscape evolution in the region during part of the Pliocene represented by the whole P1-P5 sequence (4-5 Ma BP). It is envisaged that this period was dominated by aeolian deposition, although fluvial and mass movement processes probably led to reworking and redistribution of some of the materials. Overall rates of subaerial deposition, however, were not substantial: pedogenic processes were active throughout, the balance between sedimentation and pedogenesis varying over time in a cyclical fashion. Phases of reduced deposition and establishment of relatively stable land surfaces were marked by the development of argillic soil profiles with clearly defined eluvial and illuvial horizons. Intervening periods of more rapid accumulation of coarser material were characterized by accretionary soil development and welding of new pedological features on existing soils as the surface accreted, first transforming existing eluvial horizons into BCt/AE horizons (siltstones) and then encouraging the syndepositional upward extension of these complex horizons. The primary basis of the alternating units of siltstones (BCt/AE horizons) and clayey siltstones (Bt horizons) lies in the cyclical change in size of particles deposited, although pedogenic translocation processes enhanced these textural differences. The underlying driving mechanism behind the pedosedimentary cycle can only be speculated upon, although it is tempting to relate the sedimentation pattern to climatic fluctuations linked to glacial advances and retreats in the Patagonian Andes during the Pliocene.
Fil: Kemp, R. A.. University of London; Reino Unido
Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina
Materia
Argentina
Micromorphology
Palaeosols
Pedosedimentary
Pliocene
Nivel de accesibilidad
acceso abierto
Condiciones de uso
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Repositorio
CONICET Digital (CONICET)
Institución
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identificador
oai:ri.conicet.gov.ar:11336/71801

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spelling Pliocene pedosedimentary cycles in the southern Pampas, ArgentinaKemp, R. A.Zárate, Marcelo ArístidesArgentinaMicromorphologyPalaeosolsPedosedimentaryPliocenehttps://purl.org/becyt/ford/1.5https://purl.org/becyt/ford/1Well-developed Bt horizons of five palaeosols (P1-P5) have been recorded previously within a 20-m-thick succession of Pliocene siltstones and clayey siltstones in the southern part of the Buenos Aires Province of Argentina. This paper reports a detailed field and micromorphological (thin section) investigation of a 6-m portion of the sequence encompassing P2 and P3. Large-scale faunal burrow infillings occur throughout: other bioturbation features in the form of channel and spongy microstructures are mainly confined to the siltstones. The intervening clayey siltstones (Bt horizons) have been affected more by shrink-swell disruption, as evidenced by slickensides and a range of striated b-fabrics in thin sections. Clay coatings, indicative of illuvial accumulation of clay translocated in suspension from overlying A or E horizons, occur in both the siltstones and clayey siltstones. The types, microstratigraphic associations and depth functions of features are interpreted in terms of changing interactions, balances and dominances between sedimentary, pedogenic and erosional processes over time, thus providing the basis for the pedosedimentary reconstruction of landscape evolution in the region during part of the Pliocene represented by the whole P1-P5 sequence (4-5 Ma BP). It is envisaged that this period was dominated by aeolian deposition, although fluvial and mass movement processes probably led to reworking and redistribution of some of the materials. Overall rates of subaerial deposition, however, were not substantial: pedogenic processes were active throughout, the balance between sedimentation and pedogenesis varying over time in a cyclical fashion. Phases of reduced deposition and establishment of relatively stable land surfaces were marked by the development of argillic soil profiles with clearly defined eluvial and illuvial horizons. Intervening periods of more rapid accumulation of coarser material were characterized by accretionary soil development and welding of new pedological features on existing soils as the surface accreted, first transforming existing eluvial horizons into BCt/AE horizons (siltstones) and then encouraging the syndepositional upward extension of these complex horizons. The primary basis of the alternating units of siltstones (BCt/AE horizons) and clayey siltstones (Bt horizons) lies in the cyclical change in size of particles deposited, although pedogenic translocation processes enhanced these textural differences. The underlying driving mechanism behind the pedosedimentary cycle can only be speculated upon, although it is tempting to relate the sedimentation pattern to climatic fluctuations linked to glacial advances and retreats in the Patagonian Andes during the Pliocene.Fil: Kemp, R. A.. University of London; Reino UnidoFil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaWiley Blackwell Publishing, Inc2000-02info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfapplication/pdfhttp://hdl.handle.net/11336/71801Kemp, R. A.; Zárate, Marcelo Arístides; Pliocene pedosedimentary cycles in the southern Pampas, Argentina; Wiley Blackwell Publishing, Inc; Sedimentology; 47; 1; 2-2000; 3-140037-0746CONICET DigitalCONICETenginfo:eu-repo/semantics/altIdentifier/url/https://onlinelibrary.wiley.com/doi/abs/10.1046/j.1365-3091.2000.00274.xinfo:eu-repo/semantics/altIdentifier/doi/10.1046/j.1365-3091.2000.00274.xinfo:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc-sa/2.5/ar/reponame:CONICET Digital (CONICET)instname:Consejo Nacional de Investigaciones Científicas y Técnicas2025-09-03T09:51:12Zoai:ri.conicet.gov.ar:11336/71801instacron:CONICETInstitucionalhttp://ri.conicet.gov.ar/Organismo científico-tecnológicoNo correspondehttp://ri.conicet.gov.ar/oai/requestdasensio@conicet.gov.ar; lcarlino@conicet.gov.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:34982025-09-03 09:51:12.57CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicasfalse
dc.title.none.fl_str_mv Pliocene pedosedimentary cycles in the southern Pampas, Argentina
title Pliocene pedosedimentary cycles in the southern Pampas, Argentina
spellingShingle Pliocene pedosedimentary cycles in the southern Pampas, Argentina
Kemp, R. A.
Argentina
Micromorphology
Palaeosols
Pedosedimentary
Pliocene
title_short Pliocene pedosedimentary cycles in the southern Pampas, Argentina
title_full Pliocene pedosedimentary cycles in the southern Pampas, Argentina
title_fullStr Pliocene pedosedimentary cycles in the southern Pampas, Argentina
title_full_unstemmed Pliocene pedosedimentary cycles in the southern Pampas, Argentina
title_sort Pliocene pedosedimentary cycles in the southern Pampas, Argentina
dc.creator.none.fl_str_mv Kemp, R. A.
Zárate, Marcelo Arístides
author Kemp, R. A.
author_facet Kemp, R. A.
Zárate, Marcelo Arístides
author_role author
author2 Zárate, Marcelo Arístides
author2_role author
dc.subject.none.fl_str_mv Argentina
Micromorphology
Palaeosols
Pedosedimentary
Pliocene
topic Argentina
Micromorphology
Palaeosols
Pedosedimentary
Pliocene
purl_subject.fl_str_mv https://purl.org/becyt/ford/1.5
https://purl.org/becyt/ford/1
dc.description.none.fl_txt_mv Well-developed Bt horizons of five palaeosols (P1-P5) have been recorded previously within a 20-m-thick succession of Pliocene siltstones and clayey siltstones in the southern part of the Buenos Aires Province of Argentina. This paper reports a detailed field and micromorphological (thin section) investigation of a 6-m portion of the sequence encompassing P2 and P3. Large-scale faunal burrow infillings occur throughout: other bioturbation features in the form of channel and spongy microstructures are mainly confined to the siltstones. The intervening clayey siltstones (Bt horizons) have been affected more by shrink-swell disruption, as evidenced by slickensides and a range of striated b-fabrics in thin sections. Clay coatings, indicative of illuvial accumulation of clay translocated in suspension from overlying A or E horizons, occur in both the siltstones and clayey siltstones. The types, microstratigraphic associations and depth functions of features are interpreted in terms of changing interactions, balances and dominances between sedimentary, pedogenic and erosional processes over time, thus providing the basis for the pedosedimentary reconstruction of landscape evolution in the region during part of the Pliocene represented by the whole P1-P5 sequence (4-5 Ma BP). It is envisaged that this period was dominated by aeolian deposition, although fluvial and mass movement processes probably led to reworking and redistribution of some of the materials. Overall rates of subaerial deposition, however, were not substantial: pedogenic processes were active throughout, the balance between sedimentation and pedogenesis varying over time in a cyclical fashion. Phases of reduced deposition and establishment of relatively stable land surfaces were marked by the development of argillic soil profiles with clearly defined eluvial and illuvial horizons. Intervening periods of more rapid accumulation of coarser material were characterized by accretionary soil development and welding of new pedological features on existing soils as the surface accreted, first transforming existing eluvial horizons into BCt/AE horizons (siltstones) and then encouraging the syndepositional upward extension of these complex horizons. The primary basis of the alternating units of siltstones (BCt/AE horizons) and clayey siltstones (Bt horizons) lies in the cyclical change in size of particles deposited, although pedogenic translocation processes enhanced these textural differences. The underlying driving mechanism behind the pedosedimentary cycle can only be speculated upon, although it is tempting to relate the sedimentation pattern to climatic fluctuations linked to glacial advances and retreats in the Patagonian Andes during the Pliocene.
Fil: Kemp, R. A.. University of London; Reino Unido
Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina
description Well-developed Bt horizons of five palaeosols (P1-P5) have been recorded previously within a 20-m-thick succession of Pliocene siltstones and clayey siltstones in the southern part of the Buenos Aires Province of Argentina. This paper reports a detailed field and micromorphological (thin section) investigation of a 6-m portion of the sequence encompassing P2 and P3. Large-scale faunal burrow infillings occur throughout: other bioturbation features in the form of channel and spongy microstructures are mainly confined to the siltstones. The intervening clayey siltstones (Bt horizons) have been affected more by shrink-swell disruption, as evidenced by slickensides and a range of striated b-fabrics in thin sections. Clay coatings, indicative of illuvial accumulation of clay translocated in suspension from overlying A or E horizons, occur in both the siltstones and clayey siltstones. The types, microstratigraphic associations and depth functions of features are interpreted in terms of changing interactions, balances and dominances between sedimentary, pedogenic and erosional processes over time, thus providing the basis for the pedosedimentary reconstruction of landscape evolution in the region during part of the Pliocene represented by the whole P1-P5 sequence (4-5 Ma BP). It is envisaged that this period was dominated by aeolian deposition, although fluvial and mass movement processes probably led to reworking and redistribution of some of the materials. Overall rates of subaerial deposition, however, were not substantial: pedogenic processes were active throughout, the balance between sedimentation and pedogenesis varying over time in a cyclical fashion. Phases of reduced deposition and establishment of relatively stable land surfaces were marked by the development of argillic soil profiles with clearly defined eluvial and illuvial horizons. Intervening periods of more rapid accumulation of coarser material were characterized by accretionary soil development and welding of new pedological features on existing soils as the surface accreted, first transforming existing eluvial horizons into BCt/AE horizons (siltstones) and then encouraging the syndepositional upward extension of these complex horizons. The primary basis of the alternating units of siltstones (BCt/AE horizons) and clayey siltstones (Bt horizons) lies in the cyclical change in size of particles deposited, although pedogenic translocation processes enhanced these textural differences. The underlying driving mechanism behind the pedosedimentary cycle can only be speculated upon, although it is tempting to relate the sedimentation pattern to climatic fluctuations linked to glacial advances and retreats in the Patagonian Andes during the Pliocene.
publishDate 2000
dc.date.none.fl_str_mv 2000-02
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/11336/71801
Kemp, R. A.; Zárate, Marcelo Arístides; Pliocene pedosedimentary cycles in the southern Pampas, Argentina; Wiley Blackwell Publishing, Inc; Sedimentology; 47; 1; 2-2000; 3-14
0037-0746
CONICET Digital
CONICET
url http://hdl.handle.net/11336/71801
identifier_str_mv Kemp, R. A.; Zárate, Marcelo Arístides; Pliocene pedosedimentary cycles in the southern Pampas, Argentina; Wiley Blackwell Publishing, Inc; Sedimentology; 47; 1; 2-2000; 3-14
0037-0746
CONICET Digital
CONICET
dc.language.none.fl_str_mv eng
language eng
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info:eu-repo/semantics/altIdentifier/doi/10.1046/j.1365-3091.2000.00274.x
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
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eu_rights_str_mv openAccess
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application/pdf
dc.publisher.none.fl_str_mv Wiley Blackwell Publishing, Inc
publisher.none.fl_str_mv Wiley Blackwell Publishing, Inc
dc.source.none.fl_str_mv reponame:CONICET Digital (CONICET)
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reponame_str CONICET Digital (CONICET)
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instname_str Consejo Nacional de Investigaciones Científicas y Técnicas
repository.name.fl_str_mv CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicas
repository.mail.fl_str_mv dasensio@conicet.gov.ar; lcarlino@conicet.gov.ar
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