Rômmulo Vieira Conceição

Universidade Federal do Rio Grande do Sul

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Co-Authors

Tiago Jalowitzki

Universidade de Brasília

Fernanda Gervasoni

Universidade Federal de Pelotas

Gustavo W. Bertotto

Universidad Nacional de La Pampa

Manuel E. Schilling

Austral University of Chile

Edinei Koester

Universidade Federal do Rio Grande do Sul

Larissa Colombo Carniel

Serviço Geológico do Brasil - CPRM

Felipe Padilha Leitzke

Universidade Federal de Pelotas

Yuji Orihashi

Hirosaki University

Stephan Klemme

University of Münster

Guilherme Mallmann

Empresa de Pesquisa Agropecuária e Extensão Rural de Santa Catarina

Cooperative Institutions

Universidade Federal do Rio Grande do Sul

Instituto de Geociencias

Universidade Federal do Rio Grande

University of Rio Grande and Rio Grande Community College

Universidade de São Paulo

Universidade do Vale do Rio dos Sinos

Pontifícia Universidade Católica do Rio Grande do Sul

National Council for Scientific and Technological Development

Universidade de Brasília

University of Chile

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The Santanápolis Syenite: Genesis and Evolution of Paleoproterozoic Shoshonitic Syenites in Northeastern Brazil

International Geology Review (2000)

Rômmulo Vieira Conceição Lauro Valentim Stoll Nardi Herbet Conceição

The Paleoproterozoic terrane of the state of Bahia, Brazil, is characterized by an important mag-matic event that resulted in the generation of large and numerous syenite complexes; the terrane constitutes one of the largest syenite provinces in the world. It includes the Itiuba (1,800km2), Santanápolis (180 km2), São Felix (32 km2), and Anuri (70 km2) complexes. These syenitic bodies of shoshonitic affiliation are silica saturated, metaluminous, and exhibit: (1) moderate to high K2O/Na2O ratios, (2) relatively high MgO contents (up to 3.0%); (3) high incompatible-element contents, particularly LILE and LREE; (4) high HREE/LREE fractionations; and (5) small Eu negative anomalies. Among these syenites, Santanápolis exhibits the greatest lithological diversity, with a porphyritic and a heterogranular facies, and diverse lithotypes that vary from leucosyenites to melanocratic syenites of cumulate origin, as well as enclaves and dikes. It intruded syntectonically at 2.1 Ga and shows magmatic flow structures and subsolidus recrystallization of quartz and alkali feldspars. The mineralogical assemblage is perthitic feldspar, diopside, hornblende, phlogopite-biotite, apatite, zircon, titanite, calcite, and monazite. Differentiation of the Santanópolis Syenite was controlled by flow segregation processes in an intermediate trachytic magma, with fractionation of early crystallized diopside, apatite, and plagioclase. The parental intermediate shoshonitic magma was extracted directly from an enriched, subduction-modified mantle characterized by anomalous concentrations of LREE and LILE elements, and isotopic parameters similar to the EMI-type.

Lile

Porphyritic

Trachyte

10.1080/00206810009465119

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Citations (13)

Geochemistry and geodynamic implications on the source of Paraná-Etendeka Large Igneous Province evidenced by the 128 Ma Rosário-6 kimberlite, southern Brazil

Lithos (2019)

Rômmulo Vieira Conceição Larissa Colombo Carniel Tiago Jalowitzki Fernanda Gervasoni Daniel Grings Cedeño

Phlogopite

Large igneous province

Chromite

10.1016/j.lithos.2019.01.012

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Citations (11)

Identification of local sources of lead in atmospheric deposits in an urban area in Southern Brazil using stable lead isotope ratios

Atmospheric Environment (2005)

Nicolai Mirlean D. Ashley Robinson Koji Kawashita M LIDIAVIGNOL Rômmulo Vieira Conceição

Lead (geology)

10.1016/j.atmosenv.2005.07.002

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Citations (33)

Evolution of Heterogeneous Mantle in the Acampamento Velho and Rodeio Velho Volcanic Events, Camaquã Basin, Southern Brazil

Gondwana Research (2005)

Delia del Pilar Montecinos de Almeida Rômmulo Vieira Conceição Farid Chemale Edinei Koester André Weissheimer de Borba

Felsic

Orogeny

10.1016/s1342-937x(05)71150-3

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Citations (17)

Petrology and geochemistry of the back-arc lithospheric mantle beneath the Payenia volcanic province (La Pampa, Argentina)

Alberto Zanetti Gustavo W. Bertotto Maurízio Mazzucchelli Christophe Hémond Rômmulo Vieira Conceição

Volcanic arc

Source

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Citations (0)

Zircon U-Pb geochronology, Sm-Nd and Pb-Pb isotope systematics of Ediacaran post-collisional high-silica Acampamento Velho volcanism at the Tupanci area, NW of the Sul-Rio-Grandense Shield, Brazil

Brazilian Journal of Geology (2017)

Carlos Augusto Sommer Felipe Padilha Leitzke Evandro Fernandes de Lima Carla Joana Santos Barreto Jean Michel Lafon

ABSTRACT: We present new U-Pb zircon ages and Sm-Nd-Pb isotopic data for volcanic and hypabyssal acid rocks from the northernmost exposure of the Acampamento Velho Formation in the NW portion of the Sul-Rio-Grandense Shield, Brazil. The first volcanic episode, grouped in the high-Ti rhyolites from the Tupanci hill, shows age of 579 ± 5.6 Ma, which is in agreement with the post-collisional Acampamento Velho Formation volcanism in the Bom Jardim Group of the Camaquã Basin. A poorly constrained age of 558 +/- 39 Ma was obtained for rhyolites from the low-Ti group at the Picados Hill, which may indicate a younger acid volcanism, or a greater time span for the volcanism of the Acampamento Velho Formation in southernmost Brazil. Regarding magmatic sources, Sm/Nd isotopic data coupled to Pb isotopes and a review of trace element geochemistry indicate different amounts of Paleoproterozoic (Dom Feliciano, Pinheiro Machado Suite) to Neoproterozoic (Rio Vacacaí terrane) lower crust melting. Our data, coupled with literature data, contribute to a better understanding of the stratigraphic evolution for the Neoproterozoic post-collisional volcanic successions of the Camaquã Basin in the Sul-Rio-Grandense Shield.

Geochronology

Baltic Shield

10.1590/2317-4889201720170064

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Citations (7)

Origin and redox conditions of the Rosário-6 alnöite of southern Brazil: Implications for the state of the mantle during Gondwana breakup

Lithos (2020)

Larissa Colombo Carniel Rômmulo Vieira Conceição Stephan Klemme Jasper Berndt Tiago Jalowitzki

Phlogopite

Trace element

Incompatible element

10.1016/j.lithos.2020.105751

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Citations (3)

In-situ FTIR analyses of bentonite under high-pressure

Applied Clay Science (2010)

Frederico Alabarse Rômmulo Vieira Conceição Naira Maria Balzaretti Flávia Schenato Ana M. R. B. Xavier

The stability of bentonite is of particular interest for containment barriers in nuclear waste disposal facilities. However, very little is known about the stability of montmorillonite (the major component of bentonite) under high-pressure (HP) conditions. The objective of this work is to investigate the stability of montmorillonite under HP conditions, using a sample of bentonite in which the major component is a dioctahedral calcium montmorillonite. This montmorillonite was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray fluorescence (XRF), specific surface area (SA), thermogravimetric analysis (TGA) and differential thermal analysis (DTA). HP experiments up to 7.7 GPa at room temperature (RT) were performed using toroidal chambers (TC). The samples were characterized by XRD after the HP processing. In-situ FTIR analyses were performed in the samples inside a diamond anvil cell (DAC) up to 8 GPa (dispersed in KBr) and up to 13 GPa (pure bentonite). In-situ FTIR measurements inside the DAC showed that montmorillonite was stable despite a reversible deformation in the Si–O bond and did not lose water up to 13 GPa. XRD analysis of the samples processed at 8 GPa at RT inside the TC showed no marked modification in the (001) reflections and b-parameter (060) reflections of montmorillonite induced by high pressure. The obtained results indicated that montmorillonite remained stable under high pressure conditions.

Bentonite

Thermogravimetric analysis

Thermal Stability

Differential thermal analysis

Diamond anvil cell

10.1016/j.clay.2010.11.017

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Citations (151)

Computerized geochemical modeling of burial diagenesis of the Eocene turbidite reservoir elements: Urucutuca Formation, Espírito Santo Basin, southeastern Brazil passive margin

Journal of Palaeogeography (2018)

Marcos Antônio Klunk Sudipta Dasgupta Rômmulo Vieira Conceição

The computerized geochemical modeling, a useful tool to understand the diagenetic processes influencing the quality of hydrocarbon reservoirs, is performed by using different modules of computer codes based on the thermodynamic and chemical kinetic principles and their associated parameters. As observed in the reservoir lithofacies deposited from the marine sediment-gravity flows, a case study of diagenesis is presented here from the Espírito Santo Basin in southeastern Brazil. The study uses the Geochemist’s Workbench (GWB™), PHREEQC™ and TOUGHREACT™ computation packages. The comparison of performances of these packages demonstrates the convergence of results from the software-based geochemical modeling with the petrographic observation of dissolution, albitization, kaolinization, and the precipitation of calcite and dolomite. Moreover, with limited data points, e.g., the sedimentary petrographic data acquired from limited number of boreholes, the computer simulation establishes itself to be a powerful quantitative method estimating the degree and type of diagenetic alteration of turbidite reservoir bodies in contact with a source of saline-water influx associated with salt tectonics. Therefore, using the limited petrographic data points, the geochemical computer-simulation method can even be utilized and extrapolated for areas where similar geological context is interpreted but no borehole data are available. Hence, porosity of turbidite reservoir lithofacies can be predicted in relation to the spatial distribution of dissolution, kaolinization, and albitization of feldspars and authigenic carbonate precipitation.

Authigenic

Overbank

10.1186/s42501-018-0009-z

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Citations (11)

Mineral chemistry from the Alfeu-I lamproite (Southern Brazil) and its contribution to understand the mantle heterogeneity under South American Plate during the Gondwana breakup

Brazilian Journal of Geology (2023)

Larissa Colombo Carniel Rômmulo Vieira Conceição Carlos Augusto Silva Provenzano Andréa Sander Felipe Padilha Leitzke

The Alfeu-I lamproite is one of the few alkaline rock occurrences in the South of Brazil that represents the alkaline event related to the South Atlantic opening and the enormous magmatic activity that formed the Paraná basalts. Alfeu-I lamproite is a diatreme facies and exhibits an inequigranular texture with macrocrysts of mica, spinel, garnet, and ilmenite and microcrysts of mica, pyroxene, and rare olivine, all immersed in a groundmass of pyroxene, spinel, perovskite, rutile, ilmenite, and, more rarely, olivine. Major element compositions of Alfeu-I pyroxene, garnet, ilmenite, mica, and olivine were determined by electron microprobe analyses, and trace element concentrations of clinopyroxene, garnet, ilmenite, and mica were measured using laser-ablation inductively coupled plasma mass spectrometry techniques. Temperature, pressure, and oxygen fugacity (fO2) conditions during the crystallization of Alfeu-I lamproite were calculated with the geothermobarometers and olivine, spinel, garnet, and orthopyroxene. The resulting mean equilibrium temperature ranges from 1375°C at 4 GPa to 1395°C at 5 GPa, whereas the fO2 points to ΔFMQ = +2.4 (at 4 GPa) and ΔFMQ = +2.2 (at 5 GPa). Rb-Sr and Sm-Nd isotopic data together with the trace element concentrations of minerals suggest that melting of a mantle source enriched in incompatible elements and volatiles due to previous subduction events occurred during the Gondwana breakup around 125 Ma ago. Fluids that may have originated from subducting slabs in the old subduction zone are probably the cause of the high fO2 conditions in Alfeu-I lamproite.

Pyroxene

Ilmenite

Trace element

Mineral redox buffer

10.1590/2317-4889202320220092

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