Age and origin of the Neoproterozoic Brauna kimberlites: Melt generation within the metasomatized base of the Sao Francisco craton, Brazil

dc.creatorDonatti, JP
dc.creatorTappe, S
dc.creatorOliveira, EP
dc.creatorHeaman, LM
dc.date2013
dc.dateAUG 30
dc.date2014-08-01T18:18:35Z
dc.date2015-11-26T17:03:36Z
dc.date2014-08-01T18:18:35Z
dc.date2015-11-26T17:03:36Z
dc.date.accessioned2018-03-28T23:51:45Z
dc.date.available2018-03-28T23:51:45Z
dc.identifierChemical Geology. Elsevier Science Bv, v. 353, n. 19, n. 35, 2013.
dc.identifier0009-2541
dc.identifierWOS:000324469400003
dc.identifier10.1016/j.chemgeo.2012.06.004
dc.identifierhttp://www.repositorio.unicamp.br/jspui/handle/REPOSIP/76969
dc.identifierhttp://repositorio.unicamp.br/jspui/handle/REPOSIP/76969
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/1279122
dc.descriptionFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.descriptionConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
dc.descriptionThe diamondiferous Brauna kimberlite field is situated in the northeast part of the Sao Francisco craton, Bahia State, Brazil, and ongoing exploration revealed three complex pipe-like bodies and nineteen dykes oriented along a N30W trend. Uranium-Pb perovskite age determinations of hypabyssal kimberlite material yielded a high-precision emplacement age of 642 +/- 6 Ma (2-sigma uncertainty). This age provides the first evidence for Neoproterozoic kimberlite magmatism in Brazil, and the Brauna kimberlites thus represent the oldest known primary source of diamonds in the Sao Francisco craton. Primary kimberlite mineralogy at Brauna comprises olivine, spinel, ilmenite, phlogopite, perovskite, apatite, as well as late-stage serpentine and carbonate. Furthermore, abundant olivine, Cr-diopside, and pyrope garnet xenocrysts are present. The most common xenoliths are wall-rock granodiorites, mantle eclogites and peridotites. The Brauna kimberlites do not fit into the classic subdivision of kimberlites and orangeites (formerly Group-II kimberlites) based on South African type occurrences. Their geochemical and isotopic signatures, with negative initial epsilon Nd values of -5.8 to -8.1 and variably enriched Sr-87/Sr-86 ratios (0.7045-0.7063), suggest that Brauna kimberlite magmas were derived from a mantle source region that was strongly metasomatized prior to kimberlite magmatism at similar to 642 Ma. In particular, the incompatible element distribution suggests that Brauna kimberlite magmas originate from the metasomatized base of the Sao Francisco craton, with only minor input from the convecting upper mantle. The Brauna kimberlites mineralogically and geochemically resemble the slightly older 'anomalous' mica kimberlites from Guaniamo in Venezuela (712 +/- 6 Ma). This may suggest that both mica-rich kimberlite occurrences formed from similarly enriched subcratonic mantle lithosphere during Late Neoproterozoic extensional tectonics related to the breakup of the supercontinent Rodinia. (c) 2012 Elsevier B.V. All rights reserved.
dc.description353
dc.description19
dc.description35
dc.descriptionFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.descriptionConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
dc.descriptionFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.descriptionConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
dc.descriptionFAPESP [07/537989]
dc.descriptionCNPq [301025/2005-3, 78989/04-0]
dc.languageen
dc.publisherElsevier Science Bv
dc.publisherAmsterdam
dc.publisherHolanda
dc.relationChemical Geology
dc.relationChem. Geol.
dc.rightsfechado
dc.rightshttp://www.elsevier.com/about/open-access/open-access-policies/article-posting-policy
dc.sourceWeb of Science
dc.subjectSao Francisco craton
dc.subjectKimberlite petrology
dc.subjectU-Pb perovskite geochronology
dc.subjectMantle geochemistry
dc.subjectRodinia breakup
dc.subjectBrazilian diamond sources
dc.subjectItapicuru Greenstone-belt
dc.subjectNorth-atlantic Craton
dc.subjectU-pb Geochronology
dc.subjectUltramafic Lamprophyres
dc.subjectWest Greenland
dc.subjectGroup-i
dc.subjectLithospheric Mantle
dc.subjectIsotope Systematics
dc.subjectGold Mineralization
dc.subjectMagmatic Evolution
dc.titleAge and origin of the Neoproterozoic Brauna kimberlites: Melt generation within the metasomatized base of the Sao Francisco craton, Brazil
dc.typeArtículos de revistas


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