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
Lenguaje:Inglés
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
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paperaa:paper_00044822_v54_n3_p248_Palma
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spelling paperaa:paper_00044822_v54_n3_p248_Palma2023-06-12T16:39:55Z Evidencias geoquímicas y neomorfismo en rocas de la Formación Chachao (Valanginiano)-anticlinal Malargüe, Mendoza Rev. Asoc. Geol. Argent. 1999;54(3):248-256 Palma, R.M. Lanés, S. Miretzky, P. Fazio, A.M. carbonate ramp Cretaceous diagenesis geochemistry Argentina 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. 1999 info:eu-repo/semantics/article info:ar-repo/semantics/artículo info:eu-repo/semantics/publishedVersion application/pdf eng info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00044822_v54_n3_p248_Palma
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
language Inglés
orig_language_str_mv eng
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
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