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Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.14/1194224
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- Title
- An Orphaned baltic terrane in the Greenland caledonides : a Sm-Nd and detrital zircon study of a high-pressure/ ultrahigh-pressure complex in Liverpool Land
- Related
- Journal of geology, Vol. 124, No. 5, (2016), p.541-567
- DOI
- 10.1086/687552
- Publisher
- University of Chicago Press
- Date
- 2016
- Author/Creator
- Brueckner, H. K
- Author/Creator
- Medaris Jr., L. G
- Author/Creator
- Belousova, E. A
- Author/Creator
- Johnston, S. M
- Author/Creator
- Griffin, W. L
- Author/Creator
- Hartz, E. H
- Author/Creator
- Hemming, S
- Author/Creator
- Ghent, E
- Author/Creator
- Bubbico, R
- Description
- Liverpool Land, at the southern tip of the Greenland Caledonides, exposes a composite metamorphic terrane: the midcrustal granulite-facies Jaettedal Complex tectonically juxtaposed against the eclogite-facies, peridotite-bearing Tvaerdal Complex. The Jaettedal Complex is a Laurentian terrane, whereas the Tvaerdal Complex was proposed by earlier investigators to be a Baltic terrane. PT estimates (880°–920°C at 35–40 kbar) and Sm-Nd mineral isochrons from Tvaerdal eclogites indicate that recrystallization occurred under ultrahigh-pressure (UHP) metamorphic conditions ≈400 m.yr. ago, the same time and under similar conditions as the Western Gneiss Complex of the Norwegian Caledonides. Detrital zircons from the Tvaerdal Complex, analyzed for U-Pb, Lu-Hf, and trace elements by laser ablation inductively coupled plasma mass spectrometry, give concordantMesoproterozoic ages but not the Archean and ≈1.8 Ga Proterozoic ages characteristic of Laurentian terranes. Most remaining concordant U-Pb ages are 411–375Ma (i.e., Scandian), which contrast with older (≈460–410 Ma) zircon ages from the Jaettedal Complex as well as other Laurentian terranes. Both the Precambrian and the Scandian age sets confirm the Tvaerdal Complex as an orphaned Baltic terrane. The Jaettedal Complex underwent a lengthy Caledonian history as part of a continental arc systemduring the closure of Iapetus, whereas the Tvaerdal Complex was a fragment of the approaching Baltic passive margin. UHP metamorphism occurred when this margin subducted into the mantle beneath Laurentia. We propose that the Tvaerdal Complex separated fromBaltica and rose through the hot mantle wedge to the base of the overriding Laurentian crust by diapirism, a process that may explain its abundant anatectic granitoid intrusions.
- Description
- 27 page(s)
- Resource Type
- journal article
- Organisation
- Macquarie University. Department of Earth and Planetary Sciences
- Organisation
- Macquarie University. National Key Centre for Geochemical Evolution and Metallogeny of Continents (GEMOC)
- Organisation
- Macquarie University. ARC Centre of Excellence for Core to Crust Fluid Systems
- Identifier
- http://hdl.handle.net/1959.14/1194224
- Identifier
- mq:61394
- Identifier
- ISSN:0022-1376
- Identifier
- mq-rm-2014006698
- Identifier
- mq_res-se-562938
- Language
- eng
- Reviewed
