Krogh, Thomas E, Kamo, Sandra, Gower, Charles F, Owen, J Victor (2002) Augmented and reassessed U–Pb geochronological data from the Labradorian–Grenvillian front in the Smokey archipelago, eastern Labrador. Canadian Journal of Earth Sciences, 39 (5) 831-843 doi:10.1139/e01-091
| Reference Type | Journal (article/letter/editorial) | ||
|---|---|---|---|
| Title | Augmented and reassessed U–Pb geochronological data from the Labradorian–Grenvillian front in the Smokey archipelago, eastern Labrador | ||
| Journal | Canadian Journal of Earth Sciences | ||
| Authors | Krogh, Thomas E | Author | |
| Kamo, Sandra | Author | ||
| Gower, Charles F | Author | ||
| Owen, J Victor | Author | ||
| Year | 2002 (May 1) | Volume | 39 |
| Issue | 5 | ||
| Publisher | Canadian Science Publishing | ||
| DOI | doi:10.1139/e01-091Search in ResearchGate | ||
| Generate Citation Formats | |||
| Mindat Ref. ID | 483670 | Long-form Identifier | mindat:1:5:483670:8 |
| GUID | 0 | ||
| Full Reference | Krogh, Thomas E, Kamo, Sandra, Gower, Charles F, Owen, J Victor (2002) Augmented and reassessed U–Pb geochronological data from the Labradorian–Grenvillian front in the Smokey archipelago, eastern Labrador. Canadian Journal of Earth Sciences, 39 (5) 831-843 doi:10.1139/e01-091 | ||
| Plain Text | Krogh, Thomas E, Kamo, Sandra, Gower, Charles F, Owen, J Victor (2002) Augmented and reassessed U–Pb geochronological data from the Labradorian–Grenvillian front in the Smokey archipelago, eastern Labrador. Canadian Journal of Earth Sciences, 39 (5) 831-843 doi:10.1139/e01-091 | ||
| In | (2002, May) Canadian Journal of Earth Sciences Vol. 39 (5) Canadian Science Publishing | ||
| Abstract/Notes | Four UPb dating sites straddling the Grenville front on the Labrador coast were investigated. Sites 1 and 2 exhibit complex intrusive, deformational, and metamorphic histories and were studied in detail, whereas two simpler outcrops (sites 3 and 4) were examined only at a reconnaissance level. At site 1, south of the Grenville front, a 1799+32 Ma granodioritic gneiss is intruded by two phases of mafic dykes, then by a 1647+75 Ma aplite and a ca. 16471500 Ma pegmatite, and lastly by the Michael gabbro. The pegmatite was metamorphosed at 1030 ± 10 Ma. Site 2 is on the Cut Throat Island thrust, which defines the Grenville front in the area. Early mylonitization occurred at 1790 ± 2 Ma, followed by 1730 ± 2 Ma pegmatite emplacement and then cooling at 1703 ± 15 Ma. A post-deformational melt pod gave a titanite age of 1662 ± 10 Ma. In the mylonitic host, based on positive correlation between Pb loss and degree of granularization in monazite, Grenvillian deformation was very short-lived. Sites 3 and 4 (north of the Cut Throat Island thrust), yielded 1709 ± 10 and 1726 ± 34 Ma ages, respectively. Lack of marked younger Pb loss demonstrates that these sites escaped both Labradorian and Grenvillian metamorphism. Emplacement, deformation, and (or) metamorphism occurred at 18001790 Ma, 17301700 Ma, 16601650 Ma, possibly at 1500 Ma, and at 10401030 Ma. The Cut Throat Island thrust was active during all events, but none was confined to it. The thrust marks the northern limit of Labradorian and Grenvillian orogenesis, but because similar pre-Labradorian history is preserved on both sides of the thrust, it is not a fundamental tectonic boundary after 1800 Ma. Nevertheless, because reactivation occurred during every geological orogenic event known in the region, it clearly represents a zone of persistent crustal weakness. | ||
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