Low-temperature thermochronology of the South Atlantic margin along Uruguay and its relation to tectonic events in West Gondwana
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The geodynamic forces acting during Jurassic-Cretaceous South Atlantic rifting provoked intense transformations
in West Gondwana, such as the reactivation of ancient basement structures, voluminous magmatism and
general uplift of the new continental margins. Low-temperature thermochronology records cooling associated
with uplift syn- and post-breakup along the Brazilian margin, while further south, in Uruguay, mostly prebreakup
uplift is identified. Thermochronometry data are scarce in Uruguay, but previous studies suggest that
basement cooling and exhumation preceded West Gondwana breakup by hundreds of millions of years. To
improve our knowledge of Uruguay's thermotectonic evolution, in this study we present 19 apatite fission-track
ages, 42 apatite and 40 zircon (UeTh)/He single crystal ages for the Uruguayan shield (UYS), from which we
modeled 19 inverse thermal histories. Our results suggest that the UYS temperatures were below 200 °C since the
early Paleozoic, and that cooling below 110 °C started during the Carboniferous, with continuous exhumation of
the basement until Early Cretaceous. The onset of this long-term uplift is correlated with orogenesis and terrane
accretions in the SW margin of West Gondwana during the Paleozoic. Lithosphere thinning and uplift preceding
breakup contributed to the continuous Late Paleozoic to middle Mesozoic exhumation, until the voluminous
volcanism of the Paraná-Etendeka Large Igneous Province (c. 133 Ma). This magmatic event, combined with the
thermal influence of the Tristão da Cunha mantle plume and rift spreading, likely raised the basement geotherm
during the Late Cretaceous. Models suggest a slight increase in temperatures of the UYS from Late Cretaceous
until the Oligocene, when a final cooling to surface temperatures took place. Our findings corroborate a long and
complex thermal history for Uruguay, with crustal uplift occurring essentially before West Gondwana breakup.
Como referenciar
MACHADO, JOÃO P.S.L.; JELINEK, ANDRÉA R.; STEPHENSON, RANDELL; GAUCHER, CLAUDIO; BICCA, MARCOS M.; CHIGLINO, LETICIA; GENEZINI, FREDERICO A. Low-temperature thermochronology of the South Atlantic margin along Uruguay and its relation to tectonic events in West Gondwana. Tectonophysics, v. 784, p. 1-21, 2020. DOI: 10.1016/j.tecto.2020.228439. Disponível em: http://repositorio.ipen.br/handle/123456789/31449. Acesso em: 27 Mar 2026.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.