Volcanic Rocks
Mostrando 1-12 de 71 artigos, teses e dissertações.
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1. The sedimentary record of wet and dry eolian systems in the Cretaceous of Southeast Brazil: stratigraphic and paleogeographic significance
Abstract Sedimentologic and stratigraphic studies of paleo-deserts from the Brazilian Cretaceous are of great potential to understand the paleoclimate and paleogeography of Gondwana during its final rifting stage. Herein, we describe and discuss two depositional units characterized by two distinct eolian systems that are bounded by a long-lived unconformity.
Braz. J. Geol.. Publicado em: 11/11/2019
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2. U-Pb SHRIMP dating of basement rocks of the Iriri-Xingu domain, Central Amazonian province, Amazonian craton, Brazil
Abstract The Iriri-Xingu domain, located in the central part of the Amazonian craton, consists of extensive occurrences of Paleoproterozoic volcanic rocks and granites with published ages of ca. 1990 to 1840 Ma, which show a strong crustal contribution for their magmas. Exposures of basement rocks are small and rare. Samples from two areas were dated in this
Braz. J. Geol.. Publicado em: 21/10/2019
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3. Provenance of the Ediacaran Salinas Formation (Araçuaí Orogen, Brazil): Clues from lithochemical data and zircon U-Pb (SHRIMP) ages of volcanic clasts
Abstract Salinas Formation occurs in a large region of the Northern Araçuaí orogen, Southeastern Brazil. It includes turbiditic wackes (> 10% matrix) to arenites (< 10% matrix), pelites and clast-supported conglomerates, metamorphosed from the biotite zone of the greenschist facies to the sillimanite zone of the amphibolite facies. Salinas Formation lies u
Braz. J. Geol.. Publicado em: 01/07/2019
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4. Geochemistry, metamorphic evolution and tectonic significance of metabasites from Caçapava do Sul, southern Brazil
Abstract This paper proposes the generation and closure of a proto-ocean and formation of an island arc in the Neoproterozoic Passo Feio Metamorphic Complex (PFMC), Caçapava do Sul region, southern Brazil. The PFMC, São Gabriel Terrane, consists of a Neoproterozoic supracrustal metavolcano-sedimentary sequence intruded by the Caçapava Granite. The study u
Braz. J. Geol.. Publicado em: 29/04/2019
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5. Petrography and detrital zircon U-Pb geochronology of sedimentary rocks of the Campo Alegre Basin, Southern Brazil: implications for Gondwana assembly
Abstract The Campo Alegre Basin is a volcano-sedimentary sequence covering an area of about 500 km 2 , located at the northeast portion of Santa Catarina state (Brazil), and formed during the late stages of the Neoproterozoic era. Three main stratigraphic units compose this basin, the lowermost of which is the Bateias Formation, corresponding to the pre-volc
Braz. J. Geol.. Publicado em: 15/04/2019
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6. The Cristalino IOCG deposit: an example of multi-stage events of hydrothermal alteration and copper mineralization
Abstract The Cristalino deposit is located 40 km east of Sossego mine, Carajás. The orebody lies along a NW-SE-striking shear zone and is mainly hosted by the Neoarchean bi-modal volcanics of the Grão Pará Group. Field work and petrographic data seconded by SEM-EDS analysis allowed recognizing an early sodic metasomatism that was followed by calcic-ferric
Braz. J. Geol.. Publicado em: 15/04/2019
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7. Stratigraphy and tectonic setting of the Barriga Negra Formation in Uruguay: an update
Abstract The aim of this work is to propose a new stratigraphic scheme of the Barriga Negra Formation, in order to solve the controversies in one of the most discussed units of Uruguay. Here, we introduce a new map (unmodified since 1984) and amend the stratigraphic profile for the Barriga Negra Formation, establishing the correct sequence, order and thickne
Braz. J. Geol.. Publicado em: 08/04/2019
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8. Genesis and Classification of Nitisols from Volcano-Sedimentary Lithology in Northeastern Brazil
ABSTRACT On the southern coast of Pernambuco State (PE), Brazil, lithotypes of the Cabo Basin (volcanic and sedimentary rocks), in association with the relief, allow the determination of the dynamics of the formation of Nitossolos Háplicos (Nitisols), including those with high levels of exchangeable aluminum. The objective of this study was to evaluate the
Rev. Bras. Ciênc. Solo. Publicado em: 14/02/2019
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9. Pedogenesis in an Archaeological Dark Earth – Mulatto Earth Catena over Volcanic Rocks in Western Amazonia, Brazil
ABSTRACT Archaeological Dark Earth (ADE) pedogenesis and pre-Columbian history are fundamental for understanding the biodiversity and pedodiversity of the Neotropical rainforest in the Amazon region. This study aimed to evaluate the morphological, physical, chemical, and mineralogical properties as well as NaOH-extractable organic matter [OM(NaOH)] in ADE an
Rev. Bras. Ciênc. Solo. Publicado em: 06/08/2018
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10. Geochemistry of the Northern Paraná Continental Flood Basalt (PCFB) Province: implications for regional chemostratigraphy
ABSTRACT: The Paraná Continental Flood Basalt (PCFB) province is one of the largest igneous provinces on Earth, but little is known about the architecture and geochemical characteristics of the lava flows. In this context, a set of borehole samples arranged in an NEE-SWW profile - more than 600 km long - located in the northern PCFB was used to define its c
Braz. J. Geol.. Publicado em: 2018-06
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11. Natural Fertility and Metals Contents in Soils of Rio Grande do Sul (Brazil)
ABSTRACT: The parent geological materials and formation factors influence the chemical, physical, and mineralogical properties and composition of the soil. Therefore, the aims of this study were to determine the chemical and some physical and mineralogical properties of the soil useful for agricultural practice; to determine the natural contents of the semit
Rev. Bras. Ciênc. Solo. Publicado em: 01/02/2018
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12. Pb isotope geochemistry and reappraisal of Sr-Nd isotopes of the Cerro Morado basic magmatism (Ischigualasto-Villa Union Triassic basin, NW Argentina): Implications for the mantle sources
ABSTRACT: Sr-Nd-Pb isotopic signatures were determined for silica-undersaturated hypabyssal alkaline basic rocks of the Los Baldecitos Formation in the Cerro Morado area, situated in the Ischigualasto - Vale de la Luna Provincial Park (northernmost San Juan Province, Argentina). The basic rocks show slight variations of the Sr-Nd-Pb isotopes and similar beha
Braz. J. Geol.. Publicado em: 2018-01