The petrology, geochronology and significance of Granite Har

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TitleThe petrology, geochronology and significance of Granite Harbour Intrusive Complex xenoliths and outcrop sampled in western McMurdo Sound, Southern Victoria Land, AntarcticaAbstractGranite Harbour Intrusive Complex xenoliths in McMurdo Volcanic Group rocks and in situ outcrops have been studied from Mount Morning, western McMurdo Sound, Antarctica. Calc-alkalic samples have whole rock signatures and normative compositions similar to the Dry Valleys 1b suite, and zircon grains in one specimen yield a 545.2 ± 4.4 Ma crystallisation age. This supports subduction-related magmatism initiating in Southern Victoria Land by 545 Ma. A second group of xenoliths is alkalic, with titanite grains in one xenolith from this group dated at 538 ± 8 Ma. Whole rock chemistry, normative compositions and geochronology of the alkalic group are comparable to the Koettlitz Glacier Alkaline Suite (KGAS). The position of a proposed lower crustal discontinuity that may form a significant basement suture in the McMurdo Sound region is newly constrained to the east of Mount Morning, perhaps along the trace of the Discovery Glacier. The boundary between East and West Antarctica may also pass along the trace of the Discovery Glacier if, as previously hypothesised, its location is controlled by the basement suture. A significant basement suture may also have provided the necessary egress for the (regionally) early and sustained magmatic activity observed at Mount Morning over the last 24 million years. 2014 The Royal Society of New Zealand.AcknowledgementsAdam Martin was supported by an Antarctica New Zealand (New Zealand Post) Antarctic scholarship and a University of Otago award from the Department of Geology. Antarctica New Zealand is thanked for logistic support. Brent Pooley and Damion Walls are thanked for help with sample preparation and analysis. JM Palin is thanked for his assistance. Andrew Allibone and an anonymous reviewer are thanked for their helpful reviews and Richard Jongens for editorial handling.

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1st AuthorMartin, A.AuthorMartin, A.Cooper, A.Price, R.Turnbull, R.Roberts, N.Year2015JournalNew Zealand Journal of Geology and GeophysicsVolume58Number1Pages33-51DOI10.1080/00288306.2014.982660URLhttps://www.scopus.com/inward/recor.....ee85c0eafdb56fc28f0d045d7Keywordsgeochronologygraniteigneous intrusionmagmatismpetrologyuranium-lead datingxenolith, AntarcticaEast AntarcticaGranite HarbourMcMurdo SoundMount MorningTransantarctic MountainsVictoria Land, rank5Author KeywordsGranite Harbour Intrusive ComplexKoettlitz Glacier Alkaline SuiteMount MorningRoss OrogenTransantarctic MountainsU-Pb geochronology

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TypeArticleCitationMartin, A., Cooper, A., Price, R., Turnbull, R. and Roberts, N. (2015). The petrology, geochronology and significance of Granite Harbour Intrusive Complex xenoliths and outcrop sampled in western McMurdo Sound, Southern Victoria Land, Antarctica. New Zealand Journal of Geology and Geophysics, 58(1): 33-51 doi:10.1080/00288306.2014.982660 IdentifierMartin2015Relevancerank5