Navegando por Autor "Lavina, Ernesto Luiz Correa"
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Item Granulite accretion to Rio de la Plata Craton, based on zircon U-Pb-Hf isotopes : tectonic implications for Columbia Supercontinent reconstruction.(2018) Girelli, Tiago Jonatan; Chemale Júnior, Farid; Lavina, Ernesto Luiz Correa; Laux, Jorge Henrique; Bongiolo, Everton Marques; Lana, Cristiano de CarvalhoThe paleogeographic reconstruction of the Rio de la Plata involved either allocthonous or autochthonous process reflecting directly the Paleoproterozoic connection of the craton to Columbia Supercontinent. Santa Maria Chico Granulite Complex is a significant fragment of Rio de la Plata intensely affected by the Brasiliano Orogeny. Zircon U-Pb-Hf isotopes by LA-ICP-MS, mineral and whole-rock chemistry and a pseudo-section are presently interpreted. U-Pb-Hf isotopes characterize two main accretionary and metamorphic events: oceanic juvenile crustal accretion (i) 2430–2290 Ma (εHf(t) = −3.17 to +7.00), with arc related metamorphism (830–870 °C, 6.7–7.2 kbar) at ~2.3 Ga; and continental arc accretion (ii) 2240–2120 Ma (εHf(t) = −4 to +2.4), with continental collision metamorphism (770–790 °C, 8.7–9.1 kbar) at 2.1–2.0 Ga. Alkaline granitic dikes related to crustal extension at 1.8 Ga cut the granulitic rocks after the stabilization of this crustal segment. The present data point to formation of Paleoproterozoic granulitic rocks of the Santa Maria Chico Granulite Complex and adjacent Nico Pérez and Rivera terranes in multi-stage volcanic arcs to continental collision environment over 370 Ma (2430 to 2060 Ma). These terranes were amalgamated in the Paleoproterozoic to the core of the Rio de la Plata Craton as part of Columbia Supercontinent and intensely reworked during the amalgamation of Western Gondwana in the Neoproterozoic.Item Post-glacial permian debris flow deposits and their paleoclimatic implications (Mariana Pimentel paleovalley, southern Paraná Basin).(2020) Coitinho, Júlia dos Reis; Kern, Henrique Parisi; Cagliari, Joice; Lavina, Ernesto Luiz Correa; Girelli, Tiago Jonatan; Tedesco, Julia; Lana, Cristiano de Carvalho; Silveira, Ariane Santos daThe end of the Late Paleozoic Ice Age was followed by a global warming climate. This climate transition is characterized by, beyond other aspects, a decrease in the intensity of physical weathering, characteristic of arid conditions, and an increase in the intensity of chemical weathering. In the southern Parana ´ Basin, the post-glacial onset and intense record of “Pedra-Areia” diamictite within the Mariana Pimentel paleovalley was likely controlled by warming climate conditions and mark a period of intense rainfall and slope instability. To test this hypothesis, we have performed facies and sequence stratigraphy analysis on cores located within the Mariana Pimentel paleovalley, and U–Pb-Hf investigations to acquire sediment provenance information. Diamictite deposits were produced by debris flow processes, which transported regolith from the valley wall to the bottom, eroding and incorporating mud and peat when reaching the bottom of the valley. The local source of sediment is explained by the sedimentological characteristics of the diamictite and zircon provenance studies. These deposits are preserved within the transgressive system tract and the abundant deposition was controlled by increasing temperature and humidity, and thus the increase in chemical weathering on the walls, forming the regolith. The development of more humid and warmer climatic conditions, contrasting with the cold and dry climate of the glacial period, was an important control over diamictite deposition.