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Ross Sea Mylonites and the timimg of intracontinental extension within the West Antarctic rift system

Smith Siddoway, Christine; Baldwin, Suzanne; Fitzgerald, Paul G; Fanning, Christopher; Luyendyk, Bruce

Description

There are few direct constraints on the timing and style of faulting in the Ross Sea sector of the West Antarctic rift system, although Cretaceous plate reconstructions indicate that Ross Sea extension between East and West Antarctica occurred prior to breakup of the Gondwana margin ca. 80 Ma. Mylonitic gneisses dredged from the eastern Ross Sea indicate shear-zone deformation considerably earlier, at 98-95 Ma. Strain analysis of fabrics indicates 85%-100% extension. Overprinting brittle...[Show more]

dc.contributor.authorSmith Siddoway, Christine
dc.contributor.authorBaldwin, Suzanne
dc.contributor.authorFitzgerald, Paul G
dc.contributor.authorFanning, Christopher
dc.contributor.authorLuyendyk, Bruce
dc.date.accessioned2015-12-13T22:48:59Z
dc.date.available2015-12-13T22:48:59Z
dc.identifier.issn0091-7613
dc.identifier.urihttp://hdl.handle.net/1885/80324
dc.description.abstractThere are few direct constraints on the timing and style of faulting in the Ross Sea sector of the West Antarctic rift system, although Cretaceous plate reconstructions indicate that Ross Sea extension between East and West Antarctica occurred prior to breakup of the Gondwana margin ca. 80 Ma. Mylonitic gneisses dredged from the eastern Ross Sea indicate shear-zone deformation considerably earlier, at 98-95 Ma. Strain analysis of fabrics indicates 85%-100% extension. Overprinting brittle structures record translation of shear-zone gneisses into the upper crust. Samples yield sensitive high-resolution ion-microprobe U-Pb zircon ages of 102-97 Ma, correlated to Byrd Coast Granite onshore, and concordant 40Ar/39Ar biotite and K-feldspar ages of 98-95 Ma, indicating that granites were mylonitized soon after emplacement and cooled rapidly. Apatite fission-track data corroborate this rapid cooling event, and reveal a second rapid cooling event ca. 80 Ma. Evidence for contemporaneous deformation and a similar thermal evolution at Deep Sea Drilling Project Site 270 on the Ross Sea central high and for a migmatite dome on land attests to the regional extent of intracontinental extension. Extension occurred at a time of complex microplate interactions along the Cretaceous active Gondwana margin, suggesting that distributed deformation in the overriding Antarctic plate may be related to plate boundary dynamics.
dc.publisherGeological Society of America Inc
dc.sourceGeology
dc.subjectKeywords: Plate boundary dynamics; Thermal evolution; Brittleness; Carbonates; Cooling; Deformation; Feldspar; Granite; Oceanography; Geology; Cretaceous; extensional tectonics; faulting; geochronology; mylonite; rift zone; Ross Sea; Southern Ocean Intracontinental extension; Mylonite; Thermochronology; U-Pb SHRIMP; West Antarctica
dc.titleRoss Sea Mylonites and the timimg of intracontinental extension within the West Antarctic rift system
dc.typeJournal article
local.description.notesImported from ARIES
local.description.refereedYes
local.identifier.citationvolume32
dc.date.issued2004
local.identifier.absfor040203 - Isotope Geochemistry
local.identifier.absfor040313 - Tectonics
local.identifier.ariespublicationMigratedxPub8597
local.type.statusPublished Version
local.contributor.affiliationSmith Siddoway, Christine, Colorado College
local.contributor.affiliationBaldwin, Suzanne, Syracuse University
local.contributor.affiliationFitzgerald, Paul G, Syracuse University
local.contributor.affiliationFanning, Christopher, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationLuyendyk, Bruce, University of California
local.bibliographicCitation.issue1
local.bibliographicCitation.startpage57
local.bibliographicCitation.lastpage60
local.identifier.doi10.1130/G20005.1
dc.date.updated2015-12-11T10:31:58Z
local.identifier.scopusID2-s2.0-1142293178
CollectionsANU Research Publications

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