Weathering processes at the boundary between the mercedes (cretaceous) and asencio (eocene) formations, southwestern Uruguay

The boundary between the Mercedes (Late Cretaceous) and Asencio (Eocene) formations has been a subject of controversy in the past. The morphological evidence about the contact between both formations obtained in this paper indicate that the geochemical weathering processes that took place during the...

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Autores principales:	Tofalo, Ofelia Rita de las Mercedes, Sánchez Bettucci, Leda
Publicado:	2010
Materias:	Columnar structures Cretaceous-paleogene boundary Ferrugination Uruguay Weathering column Cretaceous Eocene field survey fragmentation paleosol sandstone water erosion weathering
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01019082_v29_n4_p487_Morras http://hdl.handle.net/20.500.12110/paper_01019082_v29_n4_p487_Morras
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_01019082_v29_n4_p487_Morras
record_format	dspace
spelling	paper:paper_01019082_v29_n4_p487_Morras2023-06-08T15:10:19Z Weathering processes at the boundary between the mercedes (cretaceous) and asencio (eocene) formations, southwestern Uruguay Tofalo, Ofelia Rita de las Mercedes Sánchez Bettucci, Leda Columnar structures Cretaceous-paleogene boundary Ferrugination Uruguay Weathering column Cretaceous Eocene field survey fragmentation paleosol sandstone water erosion weathering Uruguay The boundary between the Mercedes (Late Cretaceous) and Asencio (Eocene) formations has been a subject of controversy in the past. The morphological evidence about the contact between both formations obtained in this paper indicate that the geochemical weathering processes that took place during the early Eocene forming the paleosols found in the Asencio Fm. would have penetrated deeply in the light coloured sandstones of the top of the Mercedes Fm. This is shown by a transitional level composed of a marked irregular boundary, where ferruginous materials co-exist with relicts of the greyish sandstone, as well as with pouches of ferrugination within the body of the Mercedes Fm., several meters below that boundary. Likewise, the obtained evidence shows also that the nodular strata present at the base of the Asencio Fm. are the result of the weathering of the greyish sandstones of the Mercedes Fm., due to their fragmentation and ferrugination. As a consequence, it is herein proposed that the columnar structures of the so-called Gruta del Palacio and other similar sites correspond to that transition level at the top of the Mercedes Fm.; the nuclei of the columns would be composed of the ferruginous tongues whereas the hollows would be the result of the selective water erosion of the sandstone. On the base of the field evidence, the stratigraphical nomenclature of the cited levels is discussed. Fil:Tófalo, O.R. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Sánchez-Bettucci, L. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2010 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01019082_v29_n4_p487_Morras http://hdl.handle.net/20.500.12110/paper_01019082_v29_n4_p487_Morras
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Columnar structures Cretaceous-paleogene boundary Ferrugination Uruguay Weathering column Cretaceous Eocene field survey fragmentation paleosol sandstone water erosion weathering Uruguay
spellingShingle	Columnar structures Cretaceous-paleogene boundary Ferrugination Uruguay Weathering column Cretaceous Eocene field survey fragmentation paleosol sandstone water erosion weathering Uruguay Tofalo, Ofelia Rita de las Mercedes Sánchez Bettucci, Leda Weathering processes at the boundary between the mercedes (cretaceous) and asencio (eocene) formations, southwestern Uruguay
topic_facet	Columnar structures Cretaceous-paleogene boundary Ferrugination Uruguay Weathering column Cretaceous Eocene field survey fragmentation paleosol sandstone water erosion weathering Uruguay
description	The boundary between the Mercedes (Late Cretaceous) and Asencio (Eocene) formations has been a subject of controversy in the past. The morphological evidence about the contact between both formations obtained in this paper indicate that the geochemical weathering processes that took place during the early Eocene forming the paleosols found in the Asencio Fm. would have penetrated deeply in the light coloured sandstones of the top of the Mercedes Fm. This is shown by a transitional level composed of a marked irregular boundary, where ferruginous materials co-exist with relicts of the greyish sandstone, as well as with pouches of ferrugination within the body of the Mercedes Fm., several meters below that boundary. Likewise, the obtained evidence shows also that the nodular strata present at the base of the Asencio Fm. are the result of the weathering of the greyish sandstones of the Mercedes Fm., due to their fragmentation and ferrugination. As a consequence, it is herein proposed that the columnar structures of the so-called Gruta del Palacio and other similar sites correspond to that transition level at the top of the Mercedes Fm.; the nuclei of the columns would be composed of the ferruginous tongues whereas the hollows would be the result of the selective water erosion of the sandstone. On the base of the field evidence, the stratigraphical nomenclature of the cited levels is discussed.
author	Tofalo, Ofelia Rita de las Mercedes Sánchez Bettucci, Leda
author_facet	Tofalo, Ofelia Rita de las Mercedes Sánchez Bettucci, Leda
author_sort	Tofalo, Ofelia Rita de las Mercedes
title	Weathering processes at the boundary between the mercedes (cretaceous) and asencio (eocene) formations, southwestern Uruguay
title_short	Weathering processes at the boundary between the mercedes (cretaceous) and asencio (eocene) formations, southwestern Uruguay
title_full	Weathering processes at the boundary between the mercedes (cretaceous) and asencio (eocene) formations, southwestern Uruguay
title_fullStr	Weathering processes at the boundary between the mercedes (cretaceous) and asencio (eocene) formations, southwestern Uruguay
title_full_unstemmed	Weathering processes at the boundary between the mercedes (cretaceous) and asencio (eocene) formations, southwestern Uruguay
title_sort	weathering processes at the boundary between the mercedes (cretaceous) and asencio (eocene) formations, southwestern uruguay
publishDate	2010
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01019082_v29_n4_p487_Morras http://hdl.handle.net/20.500.12110/paper_01019082_v29_n4_p487_Morras
work_keys_str_mv	AT tofaloofeliaritadelasmercedes weatheringprocessesattheboundarybetweenthemercedescretaceousandasencioeoceneformationssouthwesternuruguay AT sanchezbettuccileda weatheringprocessesattheboundarybetweenthemercedescretaceousandasencioeoceneformationssouthwesternuruguay
_version_	1768544904617656320

Weathering processes at the boundary between the mercedes (cretaceous) and asencio (eocene) formations, southwestern Uruguay

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