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Nd isotope mapping of the Allochthon Boundary Thrust on the shores of Georgian Bay, Ontario: significance for Grenvillian crustal structure and evolution

Published online by Cambridge University Press:  31 March 2015

ALAN DICKIN  and
ROBERT NORTH
ALAN DICKIN*
Affiliation:
School of Geography and Earth Sciences, McMaster University Hamilton, Ontario L8S 4K1, Canada
ROBERT NORTH
Affiliation:
School of Geography and Earth Sciences, McMaster University Hamilton, Ontario L8S 4K1, Canada
*
*Author for correspondence: [email protected]
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Abstract

Nearly 50 new Nd isotope analyses are presented for the Shawanaga region of Georgian Bay, Ontario, to study crustal evolution in the Grenvillian Central Gneiss Belt. Depleted mantle (TDM) Nd model ages are used to map a major Grenvillian tectonic boundary, the Allochthon Boundary Thrust (ABT), which in the Shawanaga area separates gneisses with TDM ages above and below 1.65 Ga. This is lower than the 1.8 Ga age cut-off observed further north, and is attributed to a southward increase in Mesoproterozoic magmatic reworking of an original Palaeoproterozoic continental margin, causing a progressive southward decrease in Nd model ages. Between Shawanaga Island and Franklin Island, Nd isotope mapping yields an ABT trajectory that closely matches published geological mapping, and passes within 100 m of four retrogressed eclogite bodies typically associated with the thrust boundary. This validation of the method gives confidence in the mapped trajectory south of Snake Island, where sparse outcrop inhibits lithological mapping. The new results suggest that published 1.7–1.9 Ga TDM ages in the Lower Go Home domain of the Central Gneiss Belt further south are also indicative of parautochthonous crust. Hence, we propose that the main ramp of the ABT is located in the immediate hangingwall of the Go Home domain, much further south than generally recognized. This has important implications for the large-scale crustal structure of the SW Grenville Province, suggesting that the ABT ramp has a similar curved trajectory to the Grenville Front and the Central Metasedimentary Belt boundary thrust.

Keywords

neodymiumSm–NdGrenvilleCanadamodel age
Type
Original Articles
Information
Geological Magazine , Volume 152 , Issue 6 , November 2015 , pp. 993 - 1008
Copyright
Copyright © Cambridge University Press 2015 

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References

Boyce, J. I. & Morris, W. A. 2002. Basement-controlled faulting of Paleozoic strata in southern Ontario, Canada: new evidence from geophysical lineament mapping. Tectonophysics 353, 151–71.CrossRefGoogle Scholar
Corrigan, D., Culshaw, N. G. & Mortensen, J. K. 1994. Pre-Grenvillian evolution and Grenville overprinting of the Parautochthonous Belt in Key Harbour, Ontario: U–Pb and field constraints. Canadian Journal of Earth Science 37, 165–81.Google Scholar
Culshaw, N. G., Corrigan, D., Drage, J. & Wallace, P. 1988. Georgian Bay geological synthesis: Key Harbour to Dillon, Grenville Province of Ontario. In Current Research Part C: Canadian Shield, pp. 129–33. Geological Survey of Canada, Paper 88–1C.Google Scholar
Culshaw, N. G., Corrigan, D., Ketchum, J. W. F., Wallace, P. & Wodicka, N. 2004 a. Precambrian Geology, Parry Sound Area. Preliminary Map P.3550, Scale 1:50 000. Ontario Geological Survey.Google Scholar
Culshaw, N. G., Corrigan, D., Ketchum, J. W. F., Wallace, P. & Wodicka, N. 2004 b. Precambrian Geology, Naiscoot Area. Preliminary Map P.3549, Scale 1:50 000. Ontario Geological Survey.Google Scholar
Culshaw, N. G. & Dostal, J. 2002. Amphibolites of the Shawanaga domain, Central Gneiss Belt, Grenville Province, Ontario: tectonic setting and implications for relations between the Central Gneiss belt and Midcontinetal USA. Precambrian Research 113, 65–85.Google Scholar
Culshaw, N. G., Gerbi, C. & Marsh, J. 2010. Softening the lower crust: modes of syn-transport transposition around and adjacent to a deep crustal granulite nappe, Parry Sound domain, Grenville Province, Canada. Tectonics 29, TC5013, 1–27.Google Scholar
Culshaw, N. G., Jamieson, R. A., Ketchum, J. W. F., Wodicka, N., Corrigan, D. & Reynolds, P. H. 1997. Transect across the northwestern Grenville orogen, Georgian Bay, Ontario: polystage convergence and extension in the lower orogenic crust. Tectonics 16, 966–82.Google Scholar
Culshaw, N. G., Ketchum, J. W. F., Wodicka, N. & Wallace, P. 1994. Deep crustal ductile extension following thrusting in the southwestern Grenville Province, Ontario. Canadian Journal of Earth Sciences 31, 160–75.Google Scholar
Culshaw, N. G., Slagstad, T., Raistrick, M. & Dostal, J. 2013. Geochemical, geochronological and isotopic constraints on the origin of members of the allochthonous Shawanaga and basal Parry Sound domains, Central Gneiss Belt, Grenville Province, Ontario. Precambrian Research 228, 131–50.Google Scholar
Davidson, A., Culshaw, N. G. & Nadeau, L. 1982. A tectono-metamorphic framework for part of the Grenville Province, Parry sound region, Ontario. In Current Research, Part A, pp. 175–90. Geological Survey of Canada, Paper 82–1A.Google Scholar
Davidson, A., Nadeau, L. & Culshaw, N. G. 2012. Classic Outcrops in the Central Gneiss Belt, Ontario – A Retrospective. 43rd Friends of the Grenville Annual Field Excursion, Guidebook.Google Scholar
Debon, F. & LeFort, P. 1983. A chemical-mineralogical classification of common plutonic rocks and associations. Transactions of the Royal Society of Edinburgh: Earth Sciences 73, 135–49.Google Scholar
DePaolo, D. J. 1981. Neodymium isotopes in the Colorado Front Range and crust-mantle evolution in the Proterozoic. Nature 291, 193–6.Google Scholar
Dickin, A. P. 1998. Pb isotope mapping of differentially uplifted Archean basement: a case study from the Grenville Province, Ontario. Precambrian Research 91, 445–54.Google Scholar
Dickin, A. P. 2000. Crustal formation in the Grenville Province: Nd-isotope evidence. Canadian Journal of Earth Sciences 37, 165–81.Google Scholar
Dickin, A. P., Cooper, D., Guo, A., Hutton, C., Martin, C., Sharma, K. N. M. & Zelek, M. 2012. Nd isotope mapping of the Lac Dumoine thrust sheet: implications for large scale crustal structure in the SW Grenville Province. Terra Nova 24, 363–72.Google Scholar
Dickin, A. P., Herrell, M., Moore, E., Cooper, D. & Pearson, S. 2014. Nd isotope mapping of allochthonous Grenvillian klippen: evidence for widespread ‘ramp-flat’ thrust geometry in the SW Grenville Province. Precambrian Research 246, 268–80.Google Scholar
Dickin, A. P. & McNutt, R. H. 1989. Nd model age mapping of the southeast margin of the Archean foreland in the Grenville province of Ontario. Geology 17, 299–302.Google Scholar
Dickin, A. P. & McNutt, R. H. 1990. Nd model-age mapping of Grenville lithotectonic domains: Mid-Proterozoic crustal evolution in Ontario. In Mid-Proterozoic Laurentia–Baltica (eds Gower, C. F., Rivers, T. & Ryan, B.), pp. 79–94. Geological Association of Canada Special Paper 38.Google Scholar
Dickin, A. P. & McNutt, R. H. 2007. The Central Metasedimentary Belt (Grenville Province) as a failed back-arc rift zone: Nd isotope evidence. Earth and Planetary Science Letters 259, 97–106.Google Scholar
Dickin, A. P., McNutt, R. H & Clifford, P. M. 1990. A neodymium isotope study of plutons near the Grenville Front in Ontario, Canada. Chemical Geology 83, 315–24.CrossRefGoogle Scholar
Dickin, A. P., Moretton, K. & North, R. 2008. Isotopic mapping of the Allochthon Boundary Thrust in the Grenville Province of Ontario, Canada. Precambrian Research 167, 260–6.Google Scholar
Indares, A. & Dunning, G. 1997. Coronitic metagabbro and eclogite from the Grenville Province of western Quebec: interpretation of U–Pb geochronology and metamorphism. Canadian Journal of Earth Sciences 34, 891–901.Google Scholar
Jagoutz, O. E., Burg, J. P., Hussain, S., Dawood, H., Pettke, T., Iizuka, T. & Maruyama, S. 2009. Construction of the granitoid crust of an island arc part I: geochronological and geochemical constraints from the plutonic Kohistan (NW Pakistan). Contributions to Mineralogy and Petrology 158, 739–55.CrossRefGoogle Scholar
Jamieson, R. A., Beaumont, C., Nguyen, M. H. & Culshaw, N. G. 2007. Synconvergent ductile flow in variable-strength continental crust: numerical models with application to the western Grenville orogen. Tectonics 26, 1–23.Google Scholar
Jamieson, R. A., Culshaw, N. G., Wodicka, N., Corrigan, D. & Ketchum, J. W. F. 1992. Timing and tectonic setting of Grenvillian metamorphism – constraints from a transect along Georgian Bay, Ontario. Journal of Metamorphic Geology 10, 321–32.CrossRefGoogle Scholar
Ketchum, J. W. F. & Davidson, A. 2000. Crustal architecture and tectonic assembly of the Central Gneiss Belt, southwestern Grenville Province, Canada: a new interpretation. Canadian Journal of Earth Sciences 37, 17–234.Google Scholar
Ketchum, J. W. F., Heaman, L. M., Krogh, T. E., Culshaw, N. G. & Jamieson, R. A. 1998. Timing and thermal influence of late orogenic extension in the lower crust: a U–Pb geochronological study from the southwest Grenville orogen, Canada. Precambrian Research 89, 25–45.CrossRefGoogle Scholar
Ketchum, J. W. F., Jamieson, R. A., Heaman, L. M., Culshaw, N. G. & Krogh, T. E. 1994. 1.45 Ga granulites in the southwestern Grenville Province: geologic setting, P–T conditions, and U–Pb geochronology. Geology 22, 215–8.Google Scholar
Marshak, S. 2004. Salients, recesses, arcs, oroclines, and syntaxes—a review of ideas concerning the formation of map-view curves in fold-thrust belts. In Thrust Tectonics and Hydrocarbon Systems (ed. McClay, K. R.), pp. 131–56. American Association of Petroleum Geologists Memoir 82.Google Scholar
Martin, C. & Dickin, A. P. 2005. Styles of crustal formation on the southeast margin of Laurentia: evidence from the central Grenville Province northwest of Lac St.-Jean, Quebec. Canadian Journal of Earth Sciences 42, 1643–52.Google Scholar
Moore, E. S. & Dickin, A. P. 2011. Evaluation of Nd isotope data for the Grenville Province of the Laurentian Shield using a Geographic Information System (GIS). Geosphere 7, 415–28.Google Scholar
Nadeau, L. & van Breemen, O. 1998. Plutonic ages and tectonic setting of the Algonquin and Muskoka allochthons, Central Gneiss Belt, Grenville Province, Ontario. Canadian Journal of Earth Sciences 35, 1423–38.Google Scholar
Rivers, T., Culshaw, N., Hynes, A., Indares, A., Jamieson, R. & Martignole, J. 2012. The Grenville Orogen—a post-lithoprobe perspective. In Tectonic Styles in Canada: The LITHOPROBE Perspective (eds Percival, J. A., Cook, F. A. & Clowes, R. M.), pp. 97–236. Geological Association of Canada Special Paper 49.Google Scholar
Rivers, T., Martignole, J., Gower, C. F. & Davidson, A. 1989. New tectonic divisions of the Grenville Province, southeastern Canadian Shield. Tectonics 8, 63–84.CrossRefGoogle Scholar
Rivers, T., van Gool, J. A. M. & Connelly, J. N. 1993. Contrasting tectonic styles in the northern Grenville province: implications for the dynamics of orogenic fronts. Geology 21, 1127–30.2.3.CO;2>CrossRefGoogle Scholar
Schwerdtner, W. M., Lu, S. J. & Landa, D. 2010. S and Z buckle folds as shear-sense indicators in the ductile realm: field examples from the Grenville Province of Ontario and the Appalachians of South Carolina. In From Rodinia to Pangea: The Lithotectonic Record of the Appalachian Region (eds Tollo, R. P., Bartholomew, M. J., Hibbard, J. P. & Karabinos, P. M.), pp. 773–94. Geological Society of America Memoir 206.Google Scholar
Slagstad, T., Culshaw, N. G., Daly, J. S. & Jamieson, R. A. 2009. Western Grenville Province holds key to midcontinental Granite-Rhyolite Province enigma. Terra Nova 21, 181–7.Google Scholar
Streckeisen, A. L. 1973. Plutonic rocks. Classification and nomenclature recommended by the IUGS subcommission on the systematics of igneous rocks. Geotimes 18, 26–30.Google Scholar
van Breemen, O. 1986. U–Pb zircon geochronology of Grenville tectonites, granulites and igneous precursors, Parry Sound, Ontario. In The Grenville Province (eds Moore, J. M., Davidson, A. & Baer, A. J.), pp. 191–207. Geological Association of Canada Special Paper 31.Google Scholar
White, D. J., Easton, R. M., Culshaw, N. G., Milkereit, B., Forsyth, D. A., Carr, S., Green, A. G. & Davidson, A. 1994. Seismic images of the Grenville Orogen in Ontario. Canadian Journal of Earth Sciences 31, 293–307.Google Scholar
Zelek, M. & Dickin, A. P. 2013. Nd isotope mapping of crustal terranes in the Parent-Clova Area, Quebec: implications for the evolution of the Laurentian margin in the Central Grenville Province. Geosciences 3, 448–65.CrossRefGoogle Scholar