Rock magnetism in late Cenozoic sediments at San Antonio de Areco, Buenos Aires province

En:

Rev. Asoc. Geol. Argent. 2004;59(3):433-442

Fecha:

2004

Formato:

application/pdf

Tipo de documento:

info:eu-repo/semantics/article
info:ar-repo/semantics/artículo
info:eu-repo/semantics/publishedVersion

Descriptores:

Environmental magnetism -  Paleoclimate -  Quaternary -  Stratigraphy -  detrital deposit -  magnetite -  paleoclimate -  paleosol -  proxy climate record

Descripción:

A geological and geophysical study in fluvial post-pampean sediments cropping out on the right bank of the Rio Areco was carried out. The sequence studied comprises the Guerrero and Río Salado members of the Luján Formation, in which three palaeosols are developed. The geophysical studies suggest an impoverishment of the detrital ferrimagnetic minerals (magnetite and titanomagnetite) in the parent material, due to the action of pedogenic processes, accompanied by the generation of two neominerales, one antiferromagnetic and the other ferrimagnetic. The ferrimagnetic mineral consists of particles of ultrafine magnetite (state of superparamagnetic domain, grain size approaching 0.01 μm) formed during periods of excess water. The antiferromagnetic minerals (hematite and/or goethite) were generated in periods of major water deficiency. The presence of these minerals would be indicating a warm and humid climate with a marked dryperiod. The oldest paleosol was developed on the Guerrero Member which correlates with the Puesto Callejón Viejo palaeosol that has an age between 10,000 and 8,000 years AP, in this profile. The Rio Salado Member and the two paleosols developed on it would have developed during the warm period known as, Megathermal, between 9,000 and 7,000 years BP. © 2004 Asociación Geológica Argentina.
Fil:Walther, A.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.
Fil:Orgeira, M.J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.
Fil:Lippai, H.F. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Identificador(es):

http://hdl.handle.net/20.500.12110/paper_00044822_v59_n3_p433_Walther

Derechos:

info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/2.5/ar