Evidencias geoquímicas y neomorfismo en rocas de la Formación Chachao (Valanginiano)-anticlinal Malargüe, Mendoza

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Geochemical features and neomorphism of Chachao Formation calcareous rocks (Valanginian)-Malargüe Anticline, Mendoza. The Lower Cretaceous Chachao Formation in the Malargüe anticline area consists of wackestone, packstone, grainstone and minor mudstone rich in benthic fauna (mainly bivalves) which w...

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Autores principales:	Palma, R.M., Lanés, S., Miretzky, P., Fazio, A.M.
Formato:	Artículo publishedVersion
Publicado:	1999
Materias:	carbonate ramp Cretaceous diagenesis geochemistry Argentina
Acceso en línea:	http://hdl.handle.net/20.500.12110/paper_00044822_v54_n3_p248_Palma https://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=artiaex&d=paper_00044822_v54_n3_p248_Palma_oai
Aporte de:	Repositorio Digital de la Universidad de Buenos Aires (UBA) de Universidad de Buenos Aires

id	I28-R145-paper_00044822_v54_n3_p248_Palma_oai
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spelling	I28-R145-paper_00044822_v54_n3_p248_Palma_oai2024-08-16 Palma, R.M. Lanés, S. Miretzky, P. Fazio, A.M. 1999 Geochemical features and neomorphism of Chachao Formation calcareous rocks (Valanginian)-Malargüe Anticline, Mendoza. The Lower Cretaceous Chachao Formation in the Malargüe anticline area consists of wackestone, packstone, grainstone and minor mudstone rich in benthic fauna (mainly bivalves) which were deposited in a shallow carbonate ramp as previous sedimentological studies have proposed. Standard petrographic, XRD, SEM, cathodoluminiscense and trace element determinations composition of micrite and microsparite mosaic crystals were undetaken in order to characterize their original mineralogy. The SEM shows that the mud fraction is composed of a mosaic texture of subhedral to anhedral micrite and microsparite crystals, both showing similar features such as smooth (unpitted) surfaces and lack of aragonite relicts. Crystal morphology also rules out the possible presence of aragonite. These features together with the microfabric, low Sr content (average: 592 ppm) of both micrite and microsparite point to an original high-magnesium calcite composition of the muds. Geochemical data from the micrite and microsparite of the mud-supported rocks of the Chachao Formation show two contrasting trends : decreasing-upward Sr and Na concentrations and increasing-upward Mg and Mn concentrations. The loss of Sr and Na are related to mineralogical stabilization of metastable carbonate particles involving the inversion of high-magnesium calcite to low-magnesium calcite, whereas local dolomitization in the upper part of the studied sequence has formed dolomite crystals showing different stages of dissolution due to meteoric and marine water influences. © 1999 Asociación Geológica Argentina. Fil:Palma, R.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Lanés, S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Miretzky, P. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. application/pdf http://hdl.handle.net/20.500.12110/paper_00044822_v54_n3_p248_Palma info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar Rev. Asoc. Geol. Argent. 1999;54(3):248-256 carbonate ramp Cretaceous diagenesis geochemistry Argentina Evidencias geoquímicas y neomorfismo en rocas de la Formación Chachao (Valanginiano)-anticlinal Malargüe, Mendoza info:eu-repo/semantics/article info:ar-repo/semantics/artículo info:eu-repo/semantics/publishedVersion https://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=artiaex&d=paper_00044822_v54_n3_p248_Palma_oai
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-145
collection	Repositorio Digital de la Universidad de Buenos Aires (UBA)
topic	carbonate ramp Cretaceous diagenesis geochemistry Argentina
spellingShingle	carbonate ramp Cretaceous diagenesis geochemistry Argentina Palma, R.M. Lanés, S. Miretzky, P. Fazio, A.M. Evidencias geoquímicas y neomorfismo en rocas de la Formación Chachao (Valanginiano)-anticlinal Malargüe, Mendoza
topic_facet	carbonate ramp Cretaceous diagenesis geochemistry Argentina
description	Geochemical features and neomorphism of Chachao Formation calcareous rocks (Valanginian)-Malargüe Anticline, Mendoza. The Lower Cretaceous Chachao Formation in the Malargüe anticline area consists of wackestone, packstone, grainstone and minor mudstone rich in benthic fauna (mainly bivalves) which were deposited in a shallow carbonate ramp as previous sedimentological studies have proposed. Standard petrographic, XRD, SEM, cathodoluminiscense and trace element determinations composition of micrite and microsparite mosaic crystals were undetaken in order to characterize their original mineralogy. The SEM shows that the mud fraction is composed of a mosaic texture of subhedral to anhedral micrite and microsparite crystals, both showing similar features such as smooth (unpitted) surfaces and lack of aragonite relicts. Crystal morphology also rules out the possible presence of aragonite. These features together with the microfabric, low Sr content (average: 592 ppm) of both micrite and microsparite point to an original high-magnesium calcite composition of the muds. Geochemical data from the micrite and microsparite of the mud-supported rocks of the Chachao Formation show two contrasting trends : decreasing-upward Sr and Na concentrations and increasing-upward Mg and Mn concentrations. The loss of Sr and Na are related to mineralogical stabilization of metastable carbonate particles involving the inversion of high-magnesium calcite to low-magnesium calcite, whereas local dolomitization in the upper part of the studied sequence has formed dolomite crystals showing different stages of dissolution due to meteoric and marine water influences. © 1999 Asociación Geológica Argentina.
format	Artículo Artículo publishedVersion
author	Palma, R.M. Lanés, S. Miretzky, P. Fazio, A.M.
author_facet	Palma, R.M. Lanés, S. Miretzky, P. Fazio, A.M.
author_sort	Palma, R.M.
title	Evidencias geoquímicas y neomorfismo en rocas de la Formación Chachao (Valanginiano)-anticlinal Malargüe, Mendoza
title_short	Evidencias geoquímicas y neomorfismo en rocas de la Formación Chachao (Valanginiano)-anticlinal Malargüe, Mendoza
title_full	Evidencias geoquímicas y neomorfismo en rocas de la Formación Chachao (Valanginiano)-anticlinal Malargüe, Mendoza
title_fullStr	Evidencias geoquímicas y neomorfismo en rocas de la Formación Chachao (Valanginiano)-anticlinal Malargüe, Mendoza
title_full_unstemmed	Evidencias geoquímicas y neomorfismo en rocas de la Formación Chachao (Valanginiano)-anticlinal Malargüe, Mendoza
title_sort	evidencias geoquímicas y neomorfismo en rocas de la formación chachao (valanginiano)-anticlinal malargüe, mendoza
publishDate	1999
url	http://hdl.handle.net/20.500.12110/paper_00044822_v54_n3_p248_Palma https://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=artiaex&d=paper_00044822_v54_n3_p248_Palma_oai
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Evidencias geoquímicas y neomorfismo en rocas de la Formación Chachao (Valanginiano)-anticlinal Malargüe, Mendoza

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