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196 results on '"Koester, Edinei"'

1. Near-collapse of the geomagnetic field may have contributed to atmospheric oxygenation and animal radiation in the Ediacaran Period

Author

Huang, Wentao, Tarduno, John A., Zhou, Tinghong, Ibañez-Mejia, Mauricio, Dal Olmo-Barbosa, Laércio, Koester, Edinei, Blackman, Eric G., Smirnov, Aleksey V., Ahrendt, Gabriel, Cottrell, Rory D., Kodama, Kenneth P., Bono, Richard K., Sibeck, David G., Li, Yong-Xiang, Nimmo, Francis, Xiao, Shuhai, and Watkeys, Michael K.

Published
2024
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30. O Terreno Pelotas e a Orogênese Pinheiro Machado: uma revisão da estratigrafia, da evolução magmática e tectônica

Author

Porcher, Carla Cristine, primary, Lenz, Cristine, additional, Koester, Edinei, additional, Bastos, Vivianne Andrade, additional, Olmo-Barbosa, Laércio Dal, additional, Vieira, Daniel Triboli, additional, Ramos, Rodrigo Chaves, additional, Pinto, Viter Magalhães, additional, Bertotti, Anelise Losangela, additional, and Fernandes, Luís Alberto Dávila, additional

Published
2021
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31. Slab failure‐related magmatism in the Pinheiro Machado Complex, southern Dom Feliciano Belt, Brazil.

Author

Bastos, Vivianne Andrade, Koester, Edinei, Lenz, Cristine, Porcher, Carla Cristine, Vieira, Daniel Triboli, Ramos, Rodrigo Chaves, and de Oliveira Loureiro, Paula

Subjects
*SLABS (Structural geology), *MAGMATISM, *GEOCHEMICAL modeling, *DIORITE, *EROSION, *CONCRETE slabs, *WATER salinization
Abstract

In the Dom Feliciano Belt, Brazil, the Pinheiro Machado Complex (PMC) includes diorites, tonalites, granodiorites, syenogranites and granites, whose evolution is related to several magmatic pulses and complex petrogenetic processes. Two magmatic stages were identified (early and late), resulting in different rock subgroups. The geochemical data showed that the early magmatism was chemically affected by partial melting. Geochemical modelling results suggest that fractional crystallization processes with assimilation of around 40% from the crustal basement and the decoupling of assimilated magma are crucial for the PMC rocks' genesis. Geochemical data also show that during the early magmatism, the subsequent process of early diorite anatexis developed by heating and continuous activity of the underlying magma chamber possibly occurred at a melting rate of 5%–10%. The hybrid rocks have contributions from the mixing process related to early terms, showing geochemical correlations in the major element curves, for the early diorite and syenogranitic melt members, at 60%–50% and 50%–40%, respectively. Slab failure tectonic context is related to the multi‐intrusive events dynamics recorded in the studied rocks. Recharge and melting events of the recently formed crust due to the constant heating of new pulses of deep slab melting would explain the magmatic interactions observed in the Complex. The results demonstrate that the studied rocks crystallized in an open system, including mixing processes to form hybrid rocks, physical disaggregation and assimilation of early intrusions, truncation, dragging and erosion of early mushes by younger pulses. [ABSTRACT FROM AUTHOR]

Published
2024
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32. Source of the synkinematic magmatism in the dorsal de canguçu transcurrent shear zone, dom feliciano belt, southern Brazil

Author

Jesus Santana, João Pedro de, primary, Koester, Edinei, additional, Vieira, Daniel Triboli, additional, Bastos, Vivianne Andrade, additional, Ramos, Rodrigo Chaves, additional, Porcher, Carla Cristine, additional, Bertotti, Anelise L., additional, Cedeño, Daniel Grings, additional, and Dal Olmo-Barbosa, Laércio, additional

Published
2023
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39. Petrogenesis of low-Ti dolerite sills from Paraná-Etendeka LIP in Cerro do Coronel region, southernmost Brazil.

Author

Simões, Matheus Silva, Sarmento, Carla Cecília Treib, Sommer, Carlos Augusto, de Lima, Evandro Fernandes, Rossetti, Lucas de Magalhães May, and Koester, Edinei

Subjects
DIABASE, PETROGENESIS, IGNEOUS provinces, LIPS, MAGNETITE, THOLEIITE, DIKES (Geology), BASALT
Abstract

In Large Igneous Provinces (LIPs), sills are a key component of the plumbing system responsible for magma transport through the crust where magma fractionation takes place. In this work, we investigate four dolerite sills related to the Paraná-Etendeka LIP from Cerro do Coronel region, southern Brazil. They are basaltic andesites composed of plagioclase, augite+pigenonite, Ti-magnetite, and rare olivine, divided into a high- and a low-MgO group. The former is more depleted in SiO2, alkalis, and trace elements, with lower FeOt/MgO ratios, higher Eu/Eu*(N), less radiogenic 87Sr/86Sr and more radiogenic 143Nd/144Nd. The composition of Cerro do Coronel dolerites resemble those of evolved rocks from Morungava Intrusions, the silica saturated tholeiite dykes in southern Brazil, and the Cuaró Dyke Swarm dolerites from Uruguay. They evolved by fractional crystallization from primitive Gramado-type basalts under FMQ-2 fO2 conditions at low pressures (<3 kbar) and underwent assimilation of variable upper and lower crust, representing shallow-depth equilibration of magmas sourced from deeper crustal levels. The studied sills share some geochemical features with the Vale do Sol Fm. lavas, although we cannot assume they have the same age, and are part of a major plumbing system related to the low-Ti magmas of the Paraná-Etendeka LIP. [ABSTRACT FROM AUTHOR]

Published
2023
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46. Insights on the evolution of the Arroio Grande Ophiolite (Dom Feliciano Belt, Brazil) from Rb-Sr and SHRIMP U-Pb isotopic geochemistry

Author

Ramos Rodrigo Chaves, Gezatt Julia Neri, Porcher Carla Cristine, Silveira Renato Luiz, Vieira Daniel Triboli, and Koester Edinei

Subjects
010504 meteorology & atmospheric sciences, Geochemistry, Geology, 010502 geochemistry & geophysics, Ophiolite, 01 natural sciences, Continental arc, Geochronology, Metasomatism, Shear zone, Protolith, 0105 earth and related environmental sciences, Earth-Surface Processes, Zircon, Terrane
Abstract

This paper presents the first Rb-Sr isotopic geochemistry study and SHRIMP zircon U-Pb dating in the Arroio Grande Ophiolite (southeasternmost Dom Feliciano Belt in Brazil), an extension of the Uruguayan Punta del Este Terrane. The metamafic units of the ophiolite show 87Sr/86Sr ratios ranging from 0.7036 to 0.7070 (recalculated at 630 Ma), which suggest a MORB magmatic source for the amphibolite protoliths and a volcanic magmatic arc source (with possible crustal contamination) for the metagabbro protoliths. Together, these features suggest a supra-subduction zone origin for these rocks, corroborating previous studies based on bulk-rock chemistry. In the metaultramafics, the 87Sr/86Sr630 ratio of the chloritite sample (0.7152) is comparable to that of the Tres Figueiras granite (0.7139), a syn-kinematic peraluminous granite related to the Ayrosa Galvao-Arroio Grande Shear Zone (which also affected the southern portion of the ophiolite, where the studied samples are located). The emplacement of the latter granite could be responsible for the metasomatism of the former serpentinites, generating talc- and chlorite-rich reaction zones. The SHRIMP U-Pb analysis of twelve chloritite zircons strengthens that assumption, as zircons with ca. 610-585 Ma (the age of the granite) were found in association with metasomatic microtextures. Zircon ages ranging from ca. 2000 to 660 Ma were also found in the chloritite. These latter ages are analogous to those found in the metasiliciclastic rocks that envelop the metaultramafic rocks of the ophiolite, so that the chloritite probably represents a blackwall reaction zone between (i) a former serpentinite, (ii) the Tres Figueiras granite, and (iii) metasiliciclastic rocks. Additionally, we perform a SHRIMP U-Pb dating in a quartz-syenite melt, which are related to a tonalitic intrusion within the metasedimentary unit (the Matarazzo Marbles) of the ophiolite. The obtained concordia age of 640 Ma constrains the minimum age of ophiolitic melange emplacement, as the tonalitic intrusion is related to continental arc magmatism (Pinheiro Machado Intrusive Suite).

Published
2018
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