Environmental history since 11,000 14C yr B.P. of the northeastern Pampas, Argentina, from alluvial sequences of the Luján River

Sedimentological, malacological, and pollen analyses from 14C-dated alluvial sections from the Luján River provide a detailed record of environmental changes during the Holocene in the northeastern Pampas of Argentina. From 11,200 to 9000 14C yr B.P., both sedimentary and biological components sugge...

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Autores principales: Prieto, A.R., Blasi, A.M., De Francesco, C.G., Fernández, C.
Formato: JOUR
Materias:
Argentina
Environmental reconstruction
Holocene
Molluscs
Pampas
Pollen
Sedimentology
alluvial deposit
depositional environment
paleoenvironment
palynology
radiocarbon dating
vegetation history
South America
Mollusca
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00335894_v62_n2_p146_Prieto
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id todo:paper_00335894_v62_n2_p146_Prieto
record_format dspace
spelling todo:paper_00335894_v62_n2_p146_Prieto2023-10-03T14:45:45Z Environmental history since 11,000 14C yr B.P. of the northeastern Pampas, Argentina, from alluvial sequences of the Luján River Prieto, A.R. Blasi, A.M. De Francesco, C.G. Fernández, C. Argentina Environmental reconstruction Holocene Molluscs Pampas Pollen Sedimentology alluvial deposit depositional environment Holocene paleoenvironment palynology radiocarbon dating vegetation history Argentina Pampas South America Mollusca Sedimentological, malacological, and pollen analyses from 14C-dated alluvial sections from the Luján River provide a detailed record of environmental changes during the Holocene in the northeastern Pampas of Argentina. From 11,200 to 9000 14C yr B.P., both sedimentary and biological components suggest that the depositional environment was eutrophic, alkaline, and freshwater to brackish shallow water bodies without significant water circulation. During this time, bioclastic sedimentation was dominant and the shallow water bodies reached maximum development as the climate became more humid, suggesting an increase in precipitation. Short-term fluctuations in climate during the last stage of this interval may have been sufficient to initiate changes in the water bodies, as reduction of the volume alternated with periods of flooding. The beginning of the evolution of shallow swamps in the wide floodplain or huge wetlands was contemporaneous with a sea level lower than the present one. From 9000 and 7000 14C yr B.P., mesotrophic, alkaline, brackish, probably anoxic swamps existed. Between 7000 and 3000 14C yr B.P., anoxic calcareous swamps were formed, with subaerial exposure and development of the Puesto Berrondo Soil (3500-2900 14C yr B.P.). A trend to a reduction of water bodies is recorded from 9000 to ca. 3000 14C yr B.P., with a significant reduction after ca. 7000 14C yr B.P. A shift to subhumid-dry climate after 7000 14C yr B.P. appears to be the main cause. During this time, an additional external forcing toward higher groundwater levels was caused by Holocene marine transgression causing changes in the water bodies levels. The climate became drier during the late Holocene (ca. 3000 yr B.P.), when clastic sedimentation increased, under subhumid-dry conditions. Flood events increased in frequency during this time. From ca. A.D. 1790 to present, the pollen record reflects widespread disturbance of the vegetation during the European settlement. © 2004 University of Washington. All rights reserved. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00335894_v62_n2_p146_Prieto
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Argentina
Environmental reconstruction
Holocene
Molluscs
Pampas
Pollen
Sedimentology
alluvial deposit
depositional environment
Holocene
paleoenvironment
palynology
radiocarbon dating
vegetation history
Argentina
Pampas
South America
Mollusca
spellingShingle Argentina
Environmental reconstruction
Holocene
Molluscs
Pampas
Pollen
Sedimentology
alluvial deposit
depositional environment
Holocene
paleoenvironment
palynology
radiocarbon dating
vegetation history
Argentina
Pampas
South America
Mollusca
Prieto, A.R.
Blasi, A.M.
De Francesco, C.G.
Fernández, C.
Environmental history since 11,000 14C yr B.P. of the northeastern Pampas, Argentina, from alluvial sequences of the Luján River
topic_facet Argentina
Environmental reconstruction
Holocene
Molluscs
Pampas
Pollen
Sedimentology
alluvial deposit
depositional environment
Holocene
paleoenvironment
palynology
radiocarbon dating
vegetation history
Argentina
Pampas
South America
Mollusca
description Sedimentological, malacological, and pollen analyses from 14C-dated alluvial sections from the Luján River provide a detailed record of environmental changes during the Holocene in the northeastern Pampas of Argentina. From 11,200 to 9000 14C yr B.P., both sedimentary and biological components suggest that the depositional environment was eutrophic, alkaline, and freshwater to brackish shallow water bodies without significant water circulation. During this time, bioclastic sedimentation was dominant and the shallow water bodies reached maximum development as the climate became more humid, suggesting an increase in precipitation. Short-term fluctuations in climate during the last stage of this interval may have been sufficient to initiate changes in the water bodies, as reduction of the volume alternated with periods of flooding. The beginning of the evolution of shallow swamps in the wide floodplain or huge wetlands was contemporaneous with a sea level lower than the present one. From 9000 and 7000 14C yr B.P., mesotrophic, alkaline, brackish, probably anoxic swamps existed. Between 7000 and 3000 14C yr B.P., anoxic calcareous swamps were formed, with subaerial exposure and development of the Puesto Berrondo Soil (3500-2900 14C yr B.P.). A trend to a reduction of water bodies is recorded from 9000 to ca. 3000 14C yr B.P., with a significant reduction after ca. 7000 14C yr B.P. A shift to subhumid-dry climate after 7000 14C yr B.P. appears to be the main cause. During this time, an additional external forcing toward higher groundwater levels was caused by Holocene marine transgression causing changes in the water bodies levels. The climate became drier during the late Holocene (ca. 3000 yr B.P.), when clastic sedimentation increased, under subhumid-dry conditions. Flood events increased in frequency during this time. From ca. A.D. 1790 to present, the pollen record reflects widespread disturbance of the vegetation during the European settlement. © 2004 University of Washington. All rights reserved.
format JOUR
author Prieto, A.R.
Blasi, A.M.
De Francesco, C.G.
Fernández, C.
author_facet Prieto, A.R.
Blasi, A.M.
De Francesco, C.G.
Fernández, C.
author_sort Prieto, A.R.
title Environmental history since 11,000 14C yr B.P. of the northeastern Pampas, Argentina, from alluvial sequences of the Luján River
title_short Environmental history since 11,000 14C yr B.P. of the northeastern Pampas, Argentina, from alluvial sequences of the Luján River
title_full Environmental history since 11,000 14C yr B.P. of the northeastern Pampas, Argentina, from alluvial sequences of the Luján River
title_fullStr Environmental history since 11,000 14C yr B.P. of the northeastern Pampas, Argentina, from alluvial sequences of the Luján River
title_full_unstemmed Environmental history since 11,000 14C yr B.P. of the northeastern Pampas, Argentina, from alluvial sequences of the Luján River
title_sort environmental history since 11,000 14c yr b.p. of the northeastern pampas, argentina, from alluvial sequences of the luján river
url http://hdl.handle.net/20.500.12110/paper_00335894_v62_n2_p146_Prieto
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