A Neoproterozoic hyper-extended margin associated with Rodinia's demise and Gondwana's build-up : the Araguaia Belt, central Brazil.

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dc.contributor.authorHodel, F.
dc.contributor.authorTrindade, Ricardo Ivan Ferreira da
dc.contributor.authorMacouin, Melina
dc.contributor.authorMeira, V.T.
dc.contributor.authorDantas, E.L.
dc.contributor.authorPaixão, Marco Antonio Pires
dc.contributor.authorRospabé, M.
dc.contributor.authorCastro, Marco Paulo de
dc.contributor.authorQueiroga, Gláucia Nascimento
dc.contributor.authorAlkmim, Ana Ramalho
dc.contributor.authorLana, Cristiano de Carvalho
dc.date.accessioned2019-05-08T13:21:21Z
dc.date.available2019-05-08T13:21:21Z
dc.date.issued2019
dc.description.abstractThe Araguaia Belt encloses a poorly constrained Pan-African (Brasiliano Cycle) continental suture marked by a series of (~750 Ma) ophiolitic units which, when properly characterized, could provide important informations on its geological history, closely linked with the Rodinia demise and further western Gondwana amalgamation. We present new bulk-rock and mineral major and trace element compositions for these ultramafic and mafic units. They mainly consist in fully serpentinized harzburgite, scarce dunite lenses and chromite pods, tectonically overlain by basaltic pillow lavas. Low Al2O3/SiO2 ratios (0.01 to 0.06), rather highMgO concentrations (42.28 to 45.29 wt%) and spinels' Cr# and Mg# ratios comprised between 0.36 and 0.51 and 0.59 and 0.72, respectively, indicate a depleted oceanic-like protolith. MORB-peridotite interactions are evidenced both by pyroxenite, olivine gabbro and diabase occurrences in the serpentinites and by high TiO2 (up to 0.42 wt%) contents in spinels from some Serra do Quatipuru serpentinites. These observations support that the Araguaia Belt ophiolitic bodies are the remnants of the upper mantle section of a MOR or subcontinental lithosphere. The serpentinites wholerock REE content can be modeled as resulting from a dry partial melting involving 14 to 24% of melt extraction, coupled with refertilization by fertile melts, generated deeper in the mantle. Such an oceanic-like setting is also supported by the N-MORB signature of Serra do Tapa and Morro do Agostinho pillow lavas basalts. All together, these results tend to infirm the supra-subduction zone (SSZ) setting previously proposed for these ophiolitic units. Important LILE, B and Li enrichments in the serpentinites likely result from a metasomatic event involving sediments-derived fluids that occurred during the obduction of the units on the Amazonian Craton. Our results combined with (1) the apparent scarcity of igneous crustal rocks, (2) the proximal nature of the metasedimentary rocks hosting the ophiolitic units, and (3) the occurrences of Amazonian Craton fragments eastward of the ophiolitic bodies, allow us to propose that the Araguaia Belt comprises a fossil ocean-continent transition (OCT) accreted on the eastern border of the Amazonian Craton.pt_BR
dc.identifier.citationHODEL, F. et al. A Neoproterozoic hyper-extended margin associated with Rodinia's demise and Gondwana's build-up : the Araguaia Belt, central Brazil. Gondwana Research, v. 66, p. 43-62, 2019. Disponível em: <https://www.sciencedirect.com/science/article/pii/S1342937X18302545>. Acesso em: 08 fev. 2019.pt_BR
dc.identifier.doihttps://doi.org/10.1016/j.gr.2018.08.010pt_BR
dc.identifier.issn1342-937X
dc.identifier.urihttp://www.repositorio.ufop.br/handle/123456789/11218
dc.identifier.uri2https://www.sciencedirect.com/science/article/pii/S1342937X18302545pt_BR
dc.language.isoen_USpt_BR
dc.rightsrestritopt_BR
dc.subjectOphiolitept_BR
dc.subjectSerpentinitespt_BR
dc.titleA Neoproterozoic hyper-extended margin associated with Rodinia's demise and Gondwana's build-up : the Araguaia Belt, central Brazil.pt_BR
dc.typeArtigo publicado em periodicopt_BR
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