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Mesoproterozoic U-Pb and Pb-Pb ages of granulites in NW Namibia: reconstructing a complete orogenic cycle

Seth, Barbara; Armstrong, Richard; Brandt, Sonke; Villa, Igor M; Kramers, Jan

Description

The chronology of the crustal evolution of the granulite facies fault-bounded Epembe Unit south of the anorthositic Kunene Intrusive Complex (KIC) in NW Namibia is presented. U-Pb zircon ages by ion microprobe (SHRIMP II) from a heterogeneous set of granulite facies rocks from the Epembe Unit reveal Mesoproterozoic ages between 1520 and 1510 Ma for prograde zircon growth. Cathodoluminescence (CL) imaging clearly shows metamorphic growth of zircon grains and zircon rims around igneous cores....[Show more]

dc.contributor.authorSeth, Barbara
dc.contributor.authorArmstrong, Richard
dc.contributor.authorBrandt, Sonke
dc.contributor.authorVilla, Igor M
dc.contributor.authorKramers, Jan
dc.date.accessioned2015-12-13T22:37:20Z
dc.date.available2015-12-13T22:37:20Z
dc.identifier.issn0301-9268
dc.identifier.urihttp://hdl.handle.net/1885/77059
dc.description.abstractThe chronology of the crustal evolution of the granulite facies fault-bounded Epembe Unit south of the anorthositic Kunene Intrusive Complex (KIC) in NW Namibia is presented. U-Pb zircon ages by ion microprobe (SHRIMP II) from a heterogeneous set of granulite facies rocks from the Epembe Unit reveal Mesoproterozoic ages between 1520 and 1510 Ma for prograde zircon growth. Cathodoluminescence (CL) imaging clearly shows metamorphic growth of zircon grains and zircon rims around igneous cores. Zircon core analyses obtained by SHRIMP yield ages between 1635 and 1810Ma. These ages are comparable to those of the Epupa basement and indicate derivation of the inherited zircon cores from Palaeoproterozoic protoliths. Pb-Pb stepwise leaching (PbSL) TIMS ages on peak-metamorphic garnet and retrograde sapphirine reflect granulite facies conditions at ca. 1490 to 1447 Ma. Our combined age data from the granulite facies Epembe Unit reveal a complete early Mesoproterozoic orogenic cycle between ca. 1640 and 1450 Ma. The cycle begins with erosion of the Palaeoproterozoic Epupa basement and involves sedimentation, burial down to the crust-mantle boundary leading to high-grade metamorphism and rapid exhumation. An orogenic cycle of this age matches in time with events dated in the Pinwarian (Grenville Province, Canada), in the Amazonian craton (Brazil) and in the Gothian (Baltic Shield, Sweden) but has not been reported in southwestern Africa before.
dc.publisherElsevier
dc.sourcePrecambrian Research
dc.subjectKeywords: lead; uranium; crustal evolution; granulite; orogeny; Proterozoic; tectonic evolution; uranium series dating; Africa; age; chronology; geology; leaching; metamorphosis; microanalysis; Namibia; review; rock; sedimentation; Africa; Namibia; Southern Africa; Granulite facies; Mesoproterozoic orogeny; Namibia; Pb-Pb stepwise leaching (PbSL); SHRIMP
dc.titleMesoproterozoic U-Pb and Pb-Pb ages of granulites in NW Namibia: reconstructing a complete orogenic cycle
dc.typeJournal article
local.description.notesImported from ARIES
local.description.refereedYes
local.identifier.citationvolume126
dc.date.issued2003
local.identifier.absfor040303 - Geochronology
local.identifier.absfor040313 - Tectonics
local.identifier.ariespublicationMigratedxPub5917
local.type.statusPublished Version
local.contributor.affiliationSeth, Barbara, Royal Holloway University of London
local.contributor.affiliationArmstrong, Richard, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationBrandt, Sonke, University of Wurzburg
local.contributor.affiliationVilla, Igor M, University of Bern
local.contributor.affiliationKramers, Jan, University of Bern
local.bibliographicCitation.startpage147
local.bibliographicCitation.lastpage168
local.identifier.doi10.1016/S0301-9268(03)00193-1
dc.date.updated2015-12-11T09:36:20Z
local.identifier.scopusID2-s2.0-0348077516
CollectionsANU Research Publications

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