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Speleothems in quartz-sandstone caves of Ponta Grossa municipality, Campos Gerais region, Paraná state, southern Brazil

Pontes, Henrique ; Fernandes, Luiz ; de Melo, Mário ; Guimarães, Gilson ; Massuqueto, Laís

International journal of speleology, 2020-05, Vol.49 (2), p.119-136 [Periódico revisado por pares]

Bologna: University of South Florida Board of Trustees, a public body corporate, having locations in Tampa, St. Petersburg, and Sarasota

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Título:
Speleothems in quartz-sandstone caves of Ponta Grossa municipality, Campos Gerais region, Paraná state, southern Brazil
Autor: Pontes, Henrique ; Fernandes, Luiz ; de Melo, Mário ; Guimarães, Gilson ; Massuqueto, Laís
Assuntos: Analytical methods ; Bedding ; Biofilms ; Biological effects ; Carboniferous ; Caves ; Chemical precipitation ; Communication ; Composition ; Conglomerates ; Cyanobacteria ; Devonian ; Diatoms ; Extracellular ; furnas formation ; Geology ; Goethite ; Gypsum ; Haematite ; Hematite ; Humidity ; Invertebrates ; Iron oxides ; Kaolinite ; Mica ; microbialites ; Microorganisms ; Mineral deposits ; Mineralization ; Muscovite ; Mushrooms ; non-carbonate rock caves ; Opal ; Porosity ; Precipitation ; Quartz ; Sandstone ; Sedimentary rocks ; Silica ; Silicon dioxide ; Silurian ; speleothems ; Stratification ; Stratigraphy ; Studies ; Substrates ; vila velha sandstone
É parte de: International journal of speleology, 2020-05, Vol.49 (2), p.119-136
Descrição: The present communication characterizes and discusses the genesis of cave speleothems developed in Furnas Formation (Silurian-Devonian) and Vila Velha sub-unit (Campo Mourão Formation, Upper Carboniferous) quartz-sandstones, in southern Brazil. The research, which involved stratigraphic and petrographic studies, was conducted to identify the faciological context of occurrence of these features, and to determine, through different analytical methods, their mineralogical composition and porosity, and also the action of microbial markers on the genesis of these secondary mineral deposits. The speleothems were classified into six types based on form, composition and genesis: (1) arborescent (coral), (2) mushroom-shaped, (3) stalactitic, (4) stalagmitic, (5) columnar with horizontal/ascending growth, and (6) fibrous. In response to substrate permoporosity, speleothems develop on all sandstone facies of the study area, mainly in sites controlled by bedding, stratification and fracturing planes. They are less frequent, however, in conglomerate and silty-clayey layers of the Furnas Formation, being composed mainly of silica (opal-A and cryptocrystalline silica) and kaolinite, with lesser contribution of gypsum and amorphous iron oxides associated with goethite and hematite. Detritic minerals such as quartz and muscovite also take part in the composition of these features. Plant and invertebrate fragments were identified, including biosignatures and microorganisms capable of favoring precipitation of silica (possibly cyanobacteria and diatom) and iron oxide (possibly Gallionella ferruginea). Such biosignatures and extracellular polymeric substances (biofilms) associated with speleothems are evidence of organomineralization, also known as biologically induced mineralization. The results, which indicate biological action on the genesis of speleothems, raise further discussion on the influence of microorganisms on the dissolution and precipitation of silica and kaolinite in the region.
Editor: Bologna: University of South Florida Board of Trustees, a public body corporate, having locations in Tampa, St. Petersburg, and Sarasota
Idioma: Inglês

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Speleothems in quartz-sandstone caves of Ponta Grossa municipality, Campos Gerais region, Paraná state, southern Brazil

Pontes, Henrique ; Fernandes, Luiz ; de Melo, Mário ; Guimarães, Gilson ; Massuqueto, Laís

Bologna: University of South Florida Board of Trustees, a public body corporate, having locations in Tampa, St. Petersburg, and Sarasota

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