Journal article
Detrital zircon Hf isotopic compositions indicate a northern Caledonian connection for the Alexander terrane
Lithosphere, Vol.5(2), pp.163-168
2013
DOI: 10.1130/L255.1
Abstract
Various plate reconstructions predict that the Alexander terrane, a Neoproterozoic-Jurassic crustal fragment now located in the North American Cordillera, evolved in proximity to the northern Appalachian-Caledonian convergent margin during assembly of supercontinent Laurussia. To test stratigraphic connections with Laurussia that are implied by these plate reconstructions, we measured the Hf isotopic compositions of 176 detrital zircons from two relevant sedimentary sequences of the Alexander terrane. An older, Upper Silurian-Lower Devonian terrestrial to shallow-marine molasse sequence yields 405-490 Ma detrital zircons with negative epsilon(Hf(t)) values and Mesoproterozoic to Paleoproterozoic Hf model ages. In combination with paleomagnetic and biogeographic constraints, these Hf data argue for the molasse strata to be now-displaced equivalents of the Old Red Sandstone and primarily sourced from crustally contaminated granitoids in the Greenland, Svalbard, or British Caledonides. Late Silurian-Early Devonian orogenesis in the Alexander terrane is therefore likely related to the Scandian-Salinic phase of Appalachian-Caledonian mountain building. Younger, Middle Devonian sequences of the Alexander terrane are endowed in 390-490 Ma detrital zircons with positive epsilon(Hf(t)) values and Neoproterozoic Hf model ages. These isotopic signatures are consistent with the erosion of local basement rocks during the opening of the Slide Mountain-Angayucham backarc rift and tectonic separation of the Alexander terrane from northern Laurussia.
Details
- Title: Subtitle
- Detrital zircon Hf isotopic compositions indicate a northern Caledonian connection for the Alexander terrane
- Creators
- Luke P Beranek - Geological Survey of CanadaCees R van Staal - Geological Survey of CanadaWilliam C McClelland - University of IowaSteve Israel - 4Yukon Geological Survey, Whitehorse, Yukon Y1A 2C6, CanadaMitch G Mihalynuk - 5British Columbia Geological Survey, Victoria, British Columbia V8W 9N3, Canada
- Resource Type
- Journal article
- Publication Details
- Lithosphere, Vol.5(2), pp.163-168
- DOI
- 10.1130/L255.1
- ISSN
- 1941-8264
- eISSN
- 1947-4253
- Language
- English
- Date published
- 2013
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984229306002771
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