BDTD - Biblioteca Digital de Teses e Dissertações
URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/2289
Biblioteca Digital de Teses e Dissertações da UFPA (BDTD). Sistema Eletrônico de Teses e Dissertações (TEDE). Projeto BDTD/UFPA e Instituto Brasileiro de Informação em Ciência e Tecnologia (IBICT).
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Navegando BDTD - Biblioteca Digital de Teses e Dissertações por Autor "ABRANTES JÚNIOR, Francisco Romério"
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Tese Acesso aberto (Open Access) Permo-triássico da Bacia do Parnaíba, Norte do Brasil: implicações paleoambientais, paleoclimáticas e paleogeográficas para o Pangea ocidental(Universidade Federal do Pará, 2016-06-03) ABRANTES JÚNIOR, Francisco Romério; NOGUEIRA, Afonso César Rodrigues; http://lattes.cnpq.br/8867836268820998The Permo-Triassic was marked by the great mass extinction of geological Earth history with losses of 90-95% of marine and terrestrial species. These were related to paleogeographic and paleoclimatic changes in part assigned to catastrophic events. In the end of Permian, arid conditions prevailed around the world as a consequence of eustatic sea level fall added to disappearance of glacial areas and large-scale closed basins multiplication. These conditions combined with the intense continentalization of Pangea supercontinent led to desertification with the development of large desert and sabka complexes. In the northern of Brazil the records of these events are found in intracratonic basins, particularly in the Parnaíba Basin. This is represented by siliciclastic-evaporitic succession from Balsas Group compound by Pedra de Fogo, Motuca and Sambaíba formations. It was recognized seven facies associations: (1) Lacustrine mudflat dominated, represented by greenish/reddish gray laminated mudstones interbedded with fine-grained sandstones and great chert content; (2) Marginal dune fields consisting of planar cross-stratified beds of fine- to medium-grained sandstones; (3) Perennial playa lake consisting dominantly of red laminated mudstones with discontinuous layers of sigmoidal sandstones; (4) Saline mudflat / Saline pan represented by reddish laminated mudstones interbedded with lenses of gypsum, limestone, and marl; (5) Sand sheet laterally consisting of continuous fine- to medium-grained sandstones with convoluted lamination, synsedimentary faults/microfaults and adhesion structures; (6) Dune fields formed by fine- to medium-grained sandstones with large-scale cross-bed sets; and (7) Volcanic plain, consisting of basalts interbedded with sandstones. During Middle Permian, the alternating between continental sabkha mudflats and shallow to deep lacustrine phases occurred in large plains in the tropical zone of western to central Pangea (AF1). This cyclicality reflected the seasonal wet and dry phases triggered by changes in the water level, low subsidence rate and narrow accommodation space. The prolonged dry stages were characterized by the advance of the marginal dune fields (AF2) as well as by establishment of large dry mudflats. In the Upper Permian, the continuous amalgamation process of supercontinent Pangea led to the uplift of central and equatorial regions resulting in the retreat of epicontinental seas. However, there were the appearance of large-scale closed basins (AF3) and extremely acid saline ephemeral lakes with saline mudflats and pans (AF4). Petrographically, the evaporate from saline pans display primary features of precipitation to eodiagenetic of gypsum and anidrite posteriorly affected by telodiagenetic processes. The extreme aridity conditions favored the decline of these great lakes and the definitive implementation of Triassic Erg. Sand sheets occurred in the marginal portion of this Erg, containing abundant ephemeral ponds and humid regions (AF5). Large dune fields advancing as consequence of the sediment availability increase, while deflation surfaces were produced by partial removal of sediment supply (AF6). The total interruption of sediment supply to the Erg in the Late Triassic provided an extreme and regional deflation surface overlapping by eojurassics volcanic rocks (AF7). The deformational analysis of the studied succession identified three different synsedimentary deformational levels at least: (I) brittle-ductile hybrid features in the contact zone between the Motuca and Sambaíba formations; (II) folds and medium-sized convolution in the middle portion of the eolic strata of Sambaíba Formation; (III) Injectites in the intertraps sandstones from Mosquito Formation. These three levels of deformed layers are separated by non- or slightly-deformed strata intervals, laterally may show a gradual increase of deformation intensity. The deformation level I occurs in the contact zone between Motuca and Sambaíba formations represented by a set of hybrid (brittleductile) features. Lateral continuity of this interval for hundreds of kilometers added to the increase in the deformation degree in the Riachão area. Furthermore, the anomalous concentration of trace elements (Cr, Co, Cu, Mn, Au, Pd, and Pt) are consistent with earthquakes of high magnitude probably product of meteoritic impact (Riachão structure). The level of strain II is marked by a set of inharmonious folds in the middle part of Sambaiba Formation. These are originated by autociclic processes related to hidroplastic deformation of sediments of sediments by dunen/draas migration and overweight. The third interval it is composed by sandstone dikes in an eojurassic volcanic rocks of Mosquito Formation. These dams were formed by hydraulic injections of sand leading to a thermal gradient increase induced by basic magmatic activities during the pre-rift phase in the Western Pangea.Dissertação Acesso aberto (Open Access) A zona de contato entre as formações Motuca e Sambaíba, Permo-Triássico da bacia do Parnaíba, regiões de Filadélfia (TO), Riachão (MA) e Loreto (MA)(Universidade Federal do Pará, 2013-02-17) ABRANTES JÚNIOR, Francisco Romério; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607; NOGUEIRA, Afonso César Rodrigues; http://lattes.cnpq.br/8867836268820998The interval between the Late Paleozoic and Early Mesozoic was marked by paleogeographic, and paleoclimatic global changes, partly attributed to catastrophic events. The intense continentalization of the supercontinent Pangaea of Terminal Permian propitiated the development of extensive deserts that succeeded the coastal and platform environments of Early Permian. The records of these events in northern Brazil are found in intracratonic basins, particularly in the Parnaíba Basin, particularly in the contact between the Permian Motuca Formation and Triassic Sambaíba Formation. The Motuca Formation consists predominantly of red laminated mudstone with subordinated lenses of gypsum, calcite and marl. In the eastern Parnaiba Basin, the facies of Motuca Formation become sandier with the expressive occurrence of sigmoidal cross-bedded sandstones. The Sambaíba Formation consists of orange cream sandstones with even parallel stratification and medium- to largescale cross-bedding. Usually, the contact between these units is sharp, where fine sandstones with cross lamination and flaser/wavy bedding (Motuca Formation) are overlaid by sandstones with sin-sedimentary faults/microfaults and convolute lamination (Sambaíba Formation). Fourteen sedimentary facies grouped into four associations (FA) were identified: FA1 – shallow lake / mudflat, FA2 - saline pan, FA3 – sand sheet and FA4 – dunes field. The FA1 interpreted as an extensive, low energy shallow lacustrine environment, with predominance of suspension and sporadically influenced by sand inflow provided of ephemeral rivers. This lake system was probably influenced by expansion and contraction periods due to changes in predominantly arid climate. The most expressive periods of contraction of lake, in the western portion of the Parnaiba Basin, was marked by development of mudflats, ephemeral saturated carbonates ponds and saline pans (FA2).Extensive sandy plains or sand sheet (FA3), locally with wetlands, was intensely reworked by eolian processes. The FA4 is interpreted as part of an erg composed of eolian dune/draas in the saturated sand zone, and subordinate dry interdune. In the contact between Motuca and Sambaiba formations occurs a deformed interval, laterally continuous for hundreds of kilometers. Brecciated and contorted bedded siltstones and mudstone (Motuca Formation) and sandstone with sinsedimentary faults/microfaults, convolute lamination and mud-filled injection dykes (Sambaíba Formation) are interpreted as seismites triggered by high magnitude earthquakes (>8 according Richter scale).Geochemical anomalies of trace elements such as Mn, Cr, Co, Cu and Ni in the contact zone between the formations, together with the presence of microparticles of metallic composition in the clay matrix of these seismites, corroborate with meteorite impacts event in the Permian-Triassic boundary, related Riachão impact structure.