期刊
NEW ZEALAND JOURNAL OF GEOLOGY AND GEOPHYSICS
卷 58, 期 1, 页码 33-51出版社
TAYLOR & FRANCIS LTD
DOI: 10.1080/00288306.2014.982660
关键词
Mount Morning; Ross Orogen; U-Pb geochronology; Transantarctic Mountains; Koettlitz Glacier Alkaline Suite; Granite Harbour Intrusive Complex
资金
- Antarctica New Zealand (New Zealand Post) Antarctic scholarship
- University of Otago award from the Department of Geology
- Natural Environment Research Council [nigl010001] Funding Source: researchfish
- NERC [nigl010001] Funding Source: UKRI
Granite 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.
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