U-Pb evidence of ~1.7 Ga crustal tectonism during the Nimrod Orogeny in the Transantarctic Mountains, Antarctica: implications for Proterozoic plate reconstructions

dc.contributor.authorGoodge, John W
dc.contributor.authorFanning, Christopher
dc.contributor.authorBennett, Victoria
dc.date.accessioned2015-12-13T23:20:38Z
dc.date.issued2001
dc.date.updated2015-12-12T09:03:56Z
dc.description.abstractThe Pacific margin of East Antarctica records a long tectonic history of crustal growth and breakup, culminating in the early Paleozoic Ross Orogeny associated with Gondwanaland amalgamation. Periods of older tectonism have been proposed (e.g. Precambrian Nimrod and Beardmore Orogenies), but the veracity of these events is difficult to document because of poor petrologic preservation, geochronologic uncertainty due to isotopic resetting, and debated geological field relationships. Of these, the Nimrod Orogeny was originally proposed as a period of Neoproterozoic metamorphism and deformation within crystalline basement rocks of the Nimrod Group, based on ∼1000 Ma K-Ar mineral ages. Later structural and thermochronologic study attributed major deformation features in the Nimrod Group to Ross-age basement reactivation. Yet, new SHRIMP ion microprobe U-Pb zircon age data for gneissic and metaigneous rocks of the Nimrod Group indicate a period of deep-crustal metamorphism and magmatism between ∼1730-1720 Ma. Igneous zircons from gneissic Archean protoliths show metamorphic overgrowths of ∼1730-1720 Ma, and an eclogitic block preserved within the gneisses contains zircons yielding an average metamorphic crystallization age of ∼1720 Ma. Deformed granodiorite that intrudes the gneisses and associated metasedimentary rocks yields a concordant zircon crystallization age of ∼1730 Ma. Despite scant petrologic evidence for these metamorphic and igneous events, the zircon ages from these diverse rock types indicate major crustal thickening, possibly due to collision, in the late Paleoproterozoic. We therefore recommend revival of the term Nimrod Orogeny to describe Paleoproterozoic tectonic events in rocks of the East Antarctic shield. Similarities in the ages of igneous and metamorphic events in the Nimrod Group and geologic units elsewhere in present-day East Antarctica, southern Australia and southwestern North America suggest they may have played a role in early supercontinent assembly. In particular, similarity with the Laurentian Mojave province is consistent with Proterozoic plate reconstructions joining ancestral East Antarctica with western Laurentia.
dc.identifier.issn0301-9268
dc.identifier.urihttp://hdl.handle.net/1885/90792
dc.publisherElsevier
dc.sourcePrecambrian Research
dc.subjectKeywords: lead; uranium; zirconium; crustal evolution; orogeny; Proterozoic; SHRIMP dating; tectonic evolution; tectonic reconstruction; age determination; Antarctica; archaean; article; crystallization; geological era; geology; geomorphology; granite; growth; micr Antarctica; Geochronology; Orogeny; Paleoproterozoic
dc.titleU-Pb evidence of ~1.7 Ga crustal tectonism during the Nimrod Orogeny in the Transantarctic Mountains, Antarctica: implications for Proterozoic plate reconstructions
dc.typeJournal article
local.bibliographicCitation.lastpage288
local.bibliographicCitation.startpage261
local.contributor.affiliationGoodge, John W, University of Minnesota
local.contributor.affiliationFanning, Christopher, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationBennett, Victoria, College of Physical and Mathematical Sciences, ANU
local.contributor.authoremailu4029993@anu.edu.au
local.contributor.authoruidFanning, Christopher, u4029993
local.contributor.authoruidBennett, Victoria, u8904005
local.description.embargo2037-12-31
local.description.notesImported from ARIES
local.description.refereedYes
local.identifier.absfor040203 - Isotope Geochemistry
local.identifier.ariespublicationMigratedxPub21248
local.identifier.citationvolume112
local.identifier.doi10.1016/S0301-9268(01)00193-0
local.identifier.scopusID2-s2.0-0035843030
local.identifier.uidSubmittedByMigrated
local.type.statusPublished Version

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