Environmental magnetism in fluvial and loessic Holocene sediments and paleosols from the Chacopampean plain (Argentina)

The magnetic signals of fluvial and loessic sediments and paleosol sequences developed in the Chacopampean plain (Buenos Aires province, Argentina) are described and interpreted. To provide an analysis of the rock magnetism, sedimentological studies were performed, which led to a stratigraphic frame...

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Autores principales: Orgeira, M.J., Walther, A.M., Tófalo, R.O., Vásquez, C., Berquó, T., Favier Dobois, C., Bohnel, H.
Formato: JOUR
Materias:
Environmental magnetism
Late cenozoic
Paleoclimate
Paleosol
Holocene
loess
paleoclimate
paleomagnetism
paleosol
pedogenesis
stratigraphy
Argentina
Buenos Aires Province
Chacopampean Plain
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_08959811_v16_n4_p259_Orgeira
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_08959811_v16_n4_p259_Orgeira2023-10-03T15:42:35Z Environmental magnetism in fluvial and loessic Holocene sediments and paleosols from the Chacopampean plain (Argentina) Orgeira, M.J. Walther, A.M. Tófalo, R.O. Vásquez, C. Berquó, T. Favier Dobois, C. Bohnel, H. Environmental magnetism Late cenozoic Paleoclimate Paleosol Holocene loess paleoclimate paleomagnetism paleosol pedogenesis stratigraphy Argentina Buenos Aires Province Chacopampean Plain The magnetic signals of fluvial and loessic sediments and paleosol sequences developed in the Chacopampean plain (Buenos Aires province, Argentina) are described and interpreted. To provide an analysis of the rock magnetism, sedimentological studies were performed, which led to a stratigraphic framework of so-called 'post-Pampean' sediments deposited in different paleoenvironments.The Luján formation, composed of fine sand and pelitic sediments, is fluvial and includes floodplain facies, whereas the La Postrera Formations is eolian but particularly loessic. Variations in the magnetic signals observed in paleosols in the units were ascribed to pedogenic processes that occurred at different stages of soil development. An extensive process of dissolution of detrital ferrimagnetic minerals was recognized. In one paleosol, dissolution was accompanied by the appearance of a superparamagnetic (SP) fraction, which may indicate that the loss is connected to subsequent formation of ferrimagnetic minerals in the same paleosol. Both processes did not act simultaneously. The abundant rainfall and absence of CO3Ca in the parent material could be necessary conditions for a defensible scenario for SP genesis. In the loessic sediments (Tapalqué locality), dissolution could be associated with the genesis of a high coercive fraction. The presence of high coercivity minerals may indicate a climate with a distinctly dry season, though their lack does not necessarily imply the absence of a dry season. © 2003 Elsevier Ltd. All rights reserved. Fil:Orgeira, M.J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Walther, A.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Tófalo, R.O. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Vásquez, C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_08959811_v16_n4_p259_Orgeira
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Environmental magnetism
Late cenozoic
Paleoclimate
Paleosol
Holocene
loess
paleoclimate
paleomagnetism
paleosol
pedogenesis
stratigraphy
Argentina
Buenos Aires Province
Chacopampean Plain
spellingShingle Environmental magnetism
Late cenozoic
Paleoclimate
Paleosol
Holocene
loess
paleoclimate
paleomagnetism
paleosol
pedogenesis
stratigraphy
Argentina
Buenos Aires Province
Chacopampean Plain
Orgeira, M.J.
Walther, A.M.
Tófalo, R.O.
Vásquez, C.
Berquó, T.
Favier Dobois, C.
Bohnel, H.
Environmental magnetism in fluvial and loessic Holocene sediments and paleosols from the Chacopampean plain (Argentina)
topic_facet Environmental magnetism
Late cenozoic
Paleoclimate
Paleosol
Holocene
loess
paleoclimate
paleomagnetism
paleosol
pedogenesis
stratigraphy
Argentina
Buenos Aires Province
Chacopampean Plain
description The magnetic signals of fluvial and loessic sediments and paleosol sequences developed in the Chacopampean plain (Buenos Aires province, Argentina) are described and interpreted. To provide an analysis of the rock magnetism, sedimentological studies were performed, which led to a stratigraphic framework of so-called 'post-Pampean' sediments deposited in different paleoenvironments.The Luján formation, composed of fine sand and pelitic sediments, is fluvial and includes floodplain facies, whereas the La Postrera Formations is eolian but particularly loessic. Variations in the magnetic signals observed in paleosols in the units were ascribed to pedogenic processes that occurred at different stages of soil development. An extensive process of dissolution of detrital ferrimagnetic minerals was recognized. In one paleosol, dissolution was accompanied by the appearance of a superparamagnetic (SP) fraction, which may indicate that the loss is connected to subsequent formation of ferrimagnetic minerals in the same paleosol. Both processes did not act simultaneously. The abundant rainfall and absence of CO3Ca in the parent material could be necessary conditions for a defensible scenario for SP genesis. In the loessic sediments (Tapalqué locality), dissolution could be associated with the genesis of a high coercive fraction. The presence of high coercivity minerals may indicate a climate with a distinctly dry season, though their lack does not necessarily imply the absence of a dry season. © 2003 Elsevier Ltd. All rights reserved.
format JOUR
author Orgeira, M.J.
Walther, A.M.
Tófalo, R.O.
Vásquez, C.
Berquó, T.
Favier Dobois, C.
Bohnel, H.
author_facet Orgeira, M.J.
Walther, A.M.
Tófalo, R.O.
Vásquez, C.
Berquó, T.
Favier Dobois, C.
Bohnel, H.
author_sort Orgeira, M.J.
title Environmental magnetism in fluvial and loessic Holocene sediments and paleosols from the Chacopampean plain (Argentina)
title_short Environmental magnetism in fluvial and loessic Holocene sediments and paleosols from the Chacopampean plain (Argentina)
title_full Environmental magnetism in fluvial and loessic Holocene sediments and paleosols from the Chacopampean plain (Argentina)
title_fullStr Environmental magnetism in fluvial and loessic Holocene sediments and paleosols from the Chacopampean plain (Argentina)
title_full_unstemmed Environmental magnetism in fluvial and loessic Holocene sediments and paleosols from the Chacopampean plain (Argentina)
title_sort environmental magnetism in fluvial and loessic holocene sediments and paleosols from the chacopampean plain (argentina)
url http://hdl.handle.net/20.500.12110/paper_08959811_v16_n4_p259_Orgeira
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