Preservation of biogenerated mixed facies: A case study from the Neoproterozoic Villa Mónica formation, Sierra La Juanita, Tandilia, Argentina

The aim of this contribution was to show through field work and mineralogical microtextural studies a complex history of weathering and diagenesis in the Villa Mónica Formation, the most ancient Neoproterozoic unit of the Tandilia System and to present a proposal of a paragenetic sequence. This unit...

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Autores principales: Zalba, Patricia Eugenia, Manassero, Marcelo Jorge, Morosi, Martín Eduardo, Conconi, María Susana
Formato: Articulo
Lenguaje:Inglés
Publicado: 2010
Materias:
Ciencias Naturales
Biogenerated rocks
Diagenesis
Neoproterozoic
Paragenetic sequence
Weathering
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/82629
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-82629
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Naturales
Biogenerated rocks
Diagenesis
Neoproterozoic
Paragenetic sequence
Weathering
spellingShingle Ciencias Naturales
Biogenerated rocks
Diagenesis
Neoproterozoic
Paragenetic sequence
Weathering
Zalba, Patricia Eugenia
Manassero, Marcelo Jorge
Morosi, Martín Eduardo
Conconi, María Susana
Preservation of biogenerated mixed facies: A case study from the Neoproterozoic Villa Mónica formation, Sierra La Juanita, Tandilia, Argentina
topic_facet Ciencias Naturales
Biogenerated rocks
Diagenesis
Neoproterozoic
Paragenetic sequence
Weathering
description The aim of this contribution was to show through field work and mineralogical microtextural studies a complex history of weathering and diagenesis in the Villa Mónica Formation, the most ancient Neoproterozoic unit of the Tandilia System and to present a proposal of a paragenetic sequence. This unit also shows microbially induced structures described here for the first time. At the Estancia La Siempre Verde, La Placeres and Don Camilo quarries, Sierra La Juanita, near Barker locality, the Villa Mónica Formation is composed of carbonate facies, classically defined for more than 40 years as siliciclastic facies and of reinterpreted mixed facies: carbonate/siliciclastic and heterolithic respectively, both bearing biosignatures. The carbonates are represented by well-preserved columnar head stromatolite boundstones and by laminar microbial mat deposits. Both of them were the host rocks - identified here for the first time - of individual or random aggregates of pyramidal quartz megacrystals and they were later dolomitized, silicified, illitized and hematized. The siliciclastics are composed of quartz grains trapped within both the stromatolites and the microbial mats, of illitic siltstones and claystones and of quartzitic sandstones. Illuviation processes transported cutans to lower horizons. Syndiagenesis involved dolomitization and silicification while burial diagenesis produced pressure-solution effects by overburden and neoformation of minerals: diagenetic illite with rutile needles, among others. Compressive movements from the SW, responsible for basin inversion: telodiagenesis (uplift, fracturing, folding and introduction of meteoric fluids), affected the Villa Mónica Formation with neoformation/transformation of minerals: kaolinite, halloysite and smectite, development of slickensides (stress cutans) and ferriargillans, hydration, dedolomitization and calcification.
format Articulo
Articulo
author Zalba, Patricia Eugenia
Manassero, Marcelo Jorge
Morosi, Martín Eduardo
Conconi, María Susana
author_facet Zalba, Patricia Eugenia
Manassero, Marcelo Jorge
Morosi, Martín Eduardo
Conconi, María Susana
author_sort Zalba, Patricia Eugenia
title Preservation of biogenerated mixed facies: A case study from the Neoproterozoic Villa Mónica formation, Sierra La Juanita, Tandilia, Argentina
title_short Preservation of biogenerated mixed facies: A case study from the Neoproterozoic Villa Mónica formation, Sierra La Juanita, Tandilia, Argentina
title_full Preservation of biogenerated mixed facies: A case study from the Neoproterozoic Villa Mónica formation, Sierra La Juanita, Tandilia, Argentina
title_fullStr Preservation of biogenerated mixed facies: A case study from the Neoproterozoic Villa Mónica formation, Sierra La Juanita, Tandilia, Argentina
title_full_unstemmed Preservation of biogenerated mixed facies: A case study from the Neoproterozoic Villa Mónica formation, Sierra La Juanita, Tandilia, Argentina
title_sort preservation of biogenerated mixed facies: a case study from the neoproterozoic villa mónica formation, sierra la juanita, tandilia, argentina
publishDate 2010
url http://sedici.unlp.edu.ar/handle/10915/82629
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