Compositional study of siliciclastics sandstones and paleosoils from the Mercedes formation (Upper Cretaceous), Uruguay

The composition and textures of epiclastic sedimentary rocks from the Mercedes Formation and the micromorphology of its paleosoils are described in order to study the provenance areas, the tectonic framework, the paleoclimatic fluctuations and the diagenetic processes affecting this unit during the...

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Autores principales:	Tofalo, Ofelia Rita de las Mercedes, Pazos, Pablo Jose, Sánchez Bettucci, Leda
Publicado:	2011
Materias:	Continental sedimentary rocks Paleosoils Paraná Basin Tectonic framework Upper cretaceous conglomerate Cretaceous metamorphism micromorphology paleosol petrography porosity provenance sandstone sedimentary basin sedimentary rock siliciclastic deposit Parana Basin Uruguay
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00044822_v68_n4_p615_Tofalo http://hdl.handle.net/20.500.12110/paper_00044822_v68_n4_p615_Tofalo
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_00044822_v68_n4_p615_Tofalo
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spelling	paper:paper_00044822_v68_n4_p615_Tofalo2025-07-30T17:10:16Z Compositional study of siliciclastics sandstones and paleosoils from the Mercedes formation (Upper Cretaceous), Uruguay Tofalo, Ofelia Rita de las Mercedes Pazos, Pablo Jose Sánchez Bettucci, Leda Continental sedimentary rocks Paleosoils Paraná Basin Tectonic framework Upper cretaceous conglomerate Cretaceous metamorphism micromorphology paleosol petrography porosity provenance sandstone sedimentary basin sedimentary rock siliciclastic deposit Parana Basin Uruguay The composition and textures of epiclastic sedimentary rocks from the Mercedes Formation and the micromorphology of its paleosoils are described in order to study the provenance areas, the tectonic framework, the paleoclimatic fluctuations and the diagenetic processes affecting this unit during the Upper Cretaceous. The Mercedes Formation is located to the west and south of Uruguay, in the Parana Basin. The combined provenance analyses on conglomerates and sandstones show two different source areas with a transitional boundary between them. Towards the north, the volcanic clasts from the underlaying Arapey Formation predominate while there is a minor input from the sandstones of the Guichón Formation and from metamorphic and plutonic sources (Precambriam basement). Besides, in the central-south area the Precambrian clasts are dominant, and fragments from the Arapey Formation are scarce, while here, the Guichón Formation is not a source unit. The sandstone petrography shows interior to continental transitional cratonic provenance. Stable grains are more abundant than metastables and instables suggesting that the sediments where deposited under warm and humid climates. The increase of metaestables altered clasts in the central-south, suggests a near source area. The diagenetic processes were not uniform resulting in a varible porosity distribution, with a predominance of secondary porosity due to dissolution. The recognized processes are clay and iron oxides illuviation, clay neoformation and recristalization, carbonate and silica precipitation and disolution. The uppermost section of this unit has paleosoils, related to the complete infilling of the basin and tectonic quiescence, that suggest a change in the climate, the presence of palygorskyte and illuvial clays imply a semiarid seasonal climate. Fil:Tófalo, O.R. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Pazos, P.J. 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. 2011 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00044822_v68_n4_p615_Tofalo http://hdl.handle.net/20.500.12110/paper_00044822_v68_n4_p615_Tofalo
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Continental sedimentary rocks Paleosoils Paraná Basin Tectonic framework Upper cretaceous conglomerate Cretaceous metamorphism micromorphology paleosol petrography porosity provenance sandstone sedimentary basin sedimentary rock siliciclastic deposit Parana Basin Uruguay
spellingShingle	Continental sedimentary rocks Paleosoils Paraná Basin Tectonic framework Upper cretaceous conglomerate Cretaceous metamorphism micromorphology paleosol petrography porosity provenance sandstone sedimentary basin sedimentary rock siliciclastic deposit Parana Basin Uruguay Tofalo, Ofelia Rita de las Mercedes Pazos, Pablo Jose Sánchez Bettucci, Leda Compositional study of siliciclastics sandstones and paleosoils from the Mercedes formation (Upper Cretaceous), Uruguay
topic_facet	Continental sedimentary rocks Paleosoils Paraná Basin Tectonic framework Upper cretaceous conglomerate Cretaceous metamorphism micromorphology paleosol petrography porosity provenance sandstone sedimentary basin sedimentary rock siliciclastic deposit Parana Basin Uruguay
description	The composition and textures of epiclastic sedimentary rocks from the Mercedes Formation and the micromorphology of its paleosoils are described in order to study the provenance areas, the tectonic framework, the paleoclimatic fluctuations and the diagenetic processes affecting this unit during the Upper Cretaceous. The Mercedes Formation is located to the west and south of Uruguay, in the Parana Basin. The combined provenance analyses on conglomerates and sandstones show two different source areas with a transitional boundary between them. Towards the north, the volcanic clasts from the underlaying Arapey Formation predominate while there is a minor input from the sandstones of the Guichón Formation and from metamorphic and plutonic sources (Precambriam basement). Besides, in the central-south area the Precambrian clasts are dominant, and fragments from the Arapey Formation are scarce, while here, the Guichón Formation is not a source unit. The sandstone petrography shows interior to continental transitional cratonic provenance. Stable grains are more abundant than metastables and instables suggesting that the sediments where deposited under warm and humid climates. The increase of metaestables altered clasts in the central-south, suggests a near source area. The diagenetic processes were not uniform resulting in a varible porosity distribution, with a predominance of secondary porosity due to dissolution. The recognized processes are clay and iron oxides illuviation, clay neoformation and recristalization, carbonate and silica precipitation and disolution. The uppermost section of this unit has paleosoils, related to the complete infilling of the basin and tectonic quiescence, that suggest a change in the climate, the presence of palygorskyte and illuvial clays imply a semiarid seasonal climate.
author	Tofalo, Ofelia Rita de las Mercedes Pazos, Pablo Jose Sánchez Bettucci, Leda
author_facet	Tofalo, Ofelia Rita de las Mercedes Pazos, Pablo Jose Sánchez Bettucci, Leda
author_sort	Tofalo, Ofelia Rita de las Mercedes
title	Compositional study of siliciclastics sandstones and paleosoils from the Mercedes formation (Upper Cretaceous), Uruguay
title_short	Compositional study of siliciclastics sandstones and paleosoils from the Mercedes formation (Upper Cretaceous), Uruguay
title_full	Compositional study of siliciclastics sandstones and paleosoils from the Mercedes formation (Upper Cretaceous), Uruguay
title_fullStr	Compositional study of siliciclastics sandstones and paleosoils from the Mercedes formation (Upper Cretaceous), Uruguay
title_full_unstemmed	Compositional study of siliciclastics sandstones and paleosoils from the Mercedes formation (Upper Cretaceous), Uruguay
title_sort	compositional study of siliciclastics sandstones and paleosoils from the mercedes formation (upper cretaceous), uruguay
publishDate	2011
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00044822_v68_n4_p615_Tofalo http://hdl.handle.net/20.500.12110/paper_00044822_v68_n4_p615_Tofalo
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_version_	1840325531297382400

Compositional study of siliciclastics sandstones and paleosoils from the Mercedes formation (Upper Cretaceous), Uruguay

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