Last Gasp of the Grenville Orogeny - Thermochronology of the Grenville Front Tectonic Zone Near Killarney, Ontario
dc.contributor.author | HAGGART, MJ | en_US |
dc.contributor.author | Jamieson, Rebecca Anne | en_US |
dc.contributor.author | REYNOLDS, PH | en_US |
dc.contributor.author | KROGH, TE | en_US |
dc.contributor.author | BEAUMONT, C. | en_US |
dc.contributor.author | CULSHAW, NG | en_US |
dc.date.accessioned | 2013-06-19T17:38:07Z | |
dc.date.available | 2013-06-19T17:38:07Z | |
dc.date.issued | 1993-09 | en_US |
dc.description.abstract | We present U-Pb (titanite, zircon) and Ar-40/Ar-39 (hornblende, mica, K-feldspar) data from a transect across the western part of the Grenville Front Tectonic Zone (GFTZ) near Killarney, Ontario. High-grade metamorphic assemblages (approximately 1450 Ma) in this part of the GFTZ pre-date the Grenvillian orogeny and were primarily exhumed, with little or no metamorphic overprinting, by Grenvillian deformation. The titanite and zircon data form a discordant array with an upper intercept of 1454 +/- 8 Ma and a lower intercept of 978 +/- 13 Ma. These data are interpreted in terms of partial lead loss during a short-lived thermal event that increased in intensity from west to east across the transect. Ar-40/Ar-39 data from hornblende indicate cooling through approximately 450-degrees-C at approximately 993-979 Ma, multiple diffusion domain models for the interpretation of discordant K-feldspar spectra indicate cooling through approximately 365-340-degrees-C at 990-960 Ma, and muscovite data indicate cooling through approximately 320-degrees-C at approximately 930 Ma. Biotite data are not easily interpreted owing to the effects of partial resetting and/or excess Ar-40. The thermochronological data suggest that a thermal event with peak temperatures of 500-600-degrees-C affected the GFTZ at approximately 980 Ma, followed by very rapid cooling to approximately 350-degrees-C. We interpret the data in terms of a tectonic model involving rapid exhumation of GFTZ rocks (in response to erosion) in the hangingwall of a crustal-scale shear zone developed during a approximately 980 Ma episode of convergence. | en_US |
dc.identifier.citation | HAGGART, MJ, RA JAMIESON, PH REYNOLDS, TE KROGH, et al. 1993. "Last Gasp of the Grenville Orogeny - Thermochronology of the Grenville Front Tectonic Zone Near Killarney, Ontario." Journal of Geology 101(5): 575-589. | en_US |
dc.identifier.issn | 0022-1376 | en_US |
dc.identifier.issue | 5 | en_US |
dc.identifier.startpage | 575 | en_US |
dc.identifier.uri | http://hdl.handle.net/10222/25779 | |
dc.identifier.volume | 101 | en_US |
dc.relation.ispartof | Journal of Geology | en_US |
dc.title | Last Gasp of the Grenville Orogeny - Thermochronology of the Grenville Front Tectonic Zone Near Killarney, Ontario | en_US |
dc.type | article | en_US |
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