Temporal Constraints on Palaeoproterozoic Eclogite formation and exhumation (Usagaran Orogen, Tanzania)

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dc.contributor.authorCollins, Alan S.
dc.contributor.authorReddya, Steven M.
dc.contributor.authorBuchana, Craig
dc.contributor.authorMruma, Abdulkarim H.
dc.date.accessioned2016-09-21T13:48:29Z
dc.date.available2016-09-21T13:48:29Z
dc.date.issued2004-06
dc.descriptionFull text can be accessed at http://www.sciencedirect.com/science/article/pii/S0012821X04002754en_US
dc.description.abstractIn-situ rock suites that preserve assemblages consistent with metamorphism to eclogite-facies conditions are absent from the Archaean. Their Palaeoproterozoic appearance is one of the markers of the onset of tectonic processes similar to those seen in the Phanerozoic Earth. We report new U–Pb Secondary Ion Mass Spectrometry (SIMS) zircon data from the oldest known eclogites (the ∼2.0 Ga Usagaran eclogites, Tanzania) that constrain the timing of high-grade metamorphism, deformation and exhumation of these eclogites and constrain the speed of these processes at this critical period in Earth history. Direct dating of metamorphic zircon from mafic eclogites, and isostructurally recrystallised zircon rims from pelites and felsic gneisses indicates that high-grade metamorphism occurred at 1999.1±1.1 Ma. The rocks were quickly cooled and exhumed at rates of ∼25 °C/Ma and 0.06–0.22 GPa/Ma, respectively, at least in part, by amphibolite-facies sinistral transpression constrained by a 1991±2 Ma pegmatite dyke that crosscuts foliation. Detrital zircons in metasedimentary gneiss protoliths were dominantly derived from two sources: (1) the Tanzanian craton, and (2) a 2400–2640 Ma source region that is compatible with a belt of reworked Archaean and Palaeoproterozoic rocks that lie in the East African Orogen.en_US
dc.identifier.citationCollins, A.S., Reddy, S.M., Buchan, C. and Mruma, A., 2004. Temporal constraints on Palaeoproterozoic eclogite formation and exhumation (Usagaran Orogen, Tanzania). Earth and Planetary Science Letters, 224(1), pp.175-192.en_US
dc.identifier.doiorg/10.1016/j.epsl.2004.04.027
dc.identifier.urihttp://hdl.handle.net/20.500.11810/3985
dc.language.isoenen_US
dc.subjectEclogiteen_US
dc.subjectPalaeoproterozoicen_US
dc.subjectSHRIMPen_US
dc.subjectU–Pb isotopesen_US
dc.subjectUsagaran Orogenen_US
dc.subjectExhumationen_US
dc.subjectZirconen_US
dc.subjectDating deformationen_US
dc.subjectTanzaniaen_US
dc.subjectGeochronologyen_US
dc.titleTemporal Constraints on Palaeoproterozoic Eclogite formation and exhumation (Usagaran Orogen, Tanzania)en_US
dc.typeJournal Articleen_US
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