A complex history of subduction, back-arc basin formation, terrane accretion and transpressional shearing characterizes the evolution of the Caribbean and northern South American margin since Jurassic times. Quantitative plate tectonic reconstructions of the area do not include Jurassic-Cretaceous back-arc terranes of which there are both geological and geophysical observations. We developed a revised plate tectonic reconstruction based on geological observations and seismic tomography models to constrain the Jurassic-Cretaceous subduction history of eastern Panthalassa, along the western margin of the Caribbean region. This reconstruction considers the opening of a Northern Andean back-arc basin at 145 Ma, the Quebradagrande back-arc, closing at 120 Ma and followed by terrane accretion and northward translation along the South American margin starting at 100 Ma. This kinematic reconstruction is tested against two previously published tectonic reconstructions via coupling with global numerical mantle convection models using CitcomS. A comparison of modeled versus tomographically imaged mantle structure reveals that subduction outboard of the South American margin, lacking in previous tectonic models, is required to reproduce mid-mantle positive seismic anomalies imaged in P-and S-wave seismic tomography beneath South America, 500-2000 km in depth. Furthermore, we show that this subduction zone is likely produced by a back-arc basin that developed along the northern Andes during the Cretaceous via trench roll-back from 145 Ma and was closed at 100 Ma. The contemporaneous opening of the Quebradagrande back-arc basin with the Rocas Verdes back-arc basin in the southern Andes is consistent with a model that invokes return flow of mantle material behind a retreating slab and may explain why extension along the Peruvian and Chilean sections of the Andean margin did not experience full crustal break-up and back-arc opening during the late Jurassic-early Cretaceous Period.
Widespread flooding of the Australian continent during the Early Cretaceous, referred to as the Eromanga Sea, deposited extensive shallow marine sediments throughout the Great Artesian Basin (GAB). This event had been considered 'out of sync' with eustatic sea level and was instead solely attributed to dynamic sub-| 3379 EAGE BRAZ et al.
A Poliomielite foi eliminada no Brasil, desde a década de 90, atribuído ao sucesso das campanhas de vacinação no país, tendo o último caso registrado em 1989. Porém uma baixa cobertura vacinal é um dos fatores de alerta, para a volta da circulação do vírus selvagem no país e das sequelas permanentes provocadas pelo vírus, exigindo assim um monitoramento contínuo no território. Este trabalho teve como objetivo analisar a distribuição espacial da cobertura vacinal (CV) da poliomielite na região Nordeste do Brasil em 2020 quanto a meta de CV ≥ 95%. Os dados públicos do indicador da Taxa de CV foram obtidos do Sistema de Informação do Programa Nacional de Imunizações no site do DATASUS. Os resultados até o momento da extração mostram a Região Nordeste com cobertura de 71,8% inferior à meta, sendo a menor taxa de CV registrada, no estado do Maranhão (60,1%) e a maior, no Ceará (86,9%). O Estado do Maranhão, também apresentou um maior número de municípios em situação crítica (23,5%),) com cobertura vacinal ≤ 50%. Os dados espaciais mostram uma tendencia de agrupamento de municípios com alta cobertura vacinal em alguns estados da região, porém não altera a conclusão de que em 2020 a população menor de um ano esteve em situação de vulnerabilidade quanto a reintrodução do vírus selvagem na maior parte dos municípios dos estados dessa região e nos demais estados brasileiros.
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