Evidencias geoquímicas y neomorfísmo en rocas de la Formación Chachao (Valanginiano)-anticlinal Malargue, Mendoza Geochemical features and neomorphism of Chachao Formation calcareous rocks (Valanginian)-Malargue Anticline, Mendoza

The Lower Cretaceous Chachao Formation in the Malargue 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 pétrographie, X...

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Publicado: 1997
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00044822_v52_n4_p248_Palma
http://hdl.handle.net/20.500.12110/paper_00044822_v52_n4_p248_Palma
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling paper:paper_00044822_v52_n4_p248_Palma2023-06-08T14:25:18Z Evidencias geoquímicas y neomorfísmo en rocas de la Formación Chachao (Valanginiano)-anticlinal Malargue, Mendoza Geochemical features and neomorphism of Chachao Formation calcareous rocks (Valanginian)-Malargue Anticline, Mendoza The Lower Cretaceous Chachao Formation in the Malargue 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 pétrographie, 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 Gcolágica. 1997 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00044822_v52_n4_p248_Palma http://hdl.handle.net/20.500.12110/paper_00044822_v52_n4_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)
description The Lower Cretaceous Chachao Formation in the Malargue 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 pétrographie, 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 Gcolágica.
title Evidencias geoquímicas y neomorfísmo en rocas de la Formación Chachao (Valanginiano)-anticlinal Malargue, Mendoza Geochemical features and neomorphism of Chachao Formation calcareous rocks (Valanginian)-Malargue Anticline, Mendoza
spellingShingle Evidencias geoquímicas y neomorfísmo en rocas de la Formación Chachao (Valanginiano)-anticlinal Malargue, Mendoza Geochemical features and neomorphism of Chachao Formation calcareous rocks (Valanginian)-Malargue Anticline, Mendoza
title_short Evidencias geoquímicas y neomorfísmo en rocas de la Formación Chachao (Valanginiano)-anticlinal Malargue, Mendoza Geochemical features and neomorphism of Chachao Formation calcareous rocks (Valanginian)-Malargue Anticline, Mendoza
title_full Evidencias geoquímicas y neomorfísmo en rocas de la Formación Chachao (Valanginiano)-anticlinal Malargue, Mendoza Geochemical features and neomorphism of Chachao Formation calcareous rocks (Valanginian)-Malargue Anticline, Mendoza
title_fullStr Evidencias geoquímicas y neomorfísmo en rocas de la Formación Chachao (Valanginiano)-anticlinal Malargue, Mendoza Geochemical features and neomorphism of Chachao Formation calcareous rocks (Valanginian)-Malargue Anticline, Mendoza
title_full_unstemmed Evidencias geoquímicas y neomorfísmo en rocas de la Formación Chachao (Valanginiano)-anticlinal Malargue, Mendoza Geochemical features and neomorphism of Chachao Formation calcareous rocks (Valanginian)-Malargue Anticline, Mendoza
title_sort evidencias geoquímicas y neomorfísmo en rocas de la formación chachao (valanginiano)-anticlinal malargue, mendoza geochemical features and neomorphism of chachao formation calcareous rocks (valanginian)-malargue anticline, mendoza
publishDate 1997
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00044822_v52_n4_p248_Palma
http://hdl.handle.net/20.500.12110/paper_00044822_v52_n4_p248_Palma
_version_ 1768542865053450240

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