Transect across the northwestern Grenville orogen, Georgian Bay, Ontario: Polystage convergence and extension in the lower orogenic crust
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The Grenville orogenic cycle, between ∼ 1190 and 980 Ma, involved accretion of magmatic arcs and/or continental terranes to the Laurentian craton. A transect across the western Central Gneiss Belt, Georgian Bay, Ontario, which crosses the boundary between parautochthonous and allochthonous units at an inferred orogenic depth of 20–30 km, offers some insights on the thermal and mechanical behavior of the lower crust during the development of the Grenville orogen. Prior to Grenvillian metamorphism, this part of Laurentia consisted largely of Meso‐proterozoic (∼ 1450 Ma) granitoid orthogneisses, granulites, and subordinate mafic and supracrustal rocks. Grenvillian convergence along the transect began with transport of the previously deformed and metamorphosed (∼ 1160 Ma) Parry Sound domain over the craton sometime between 1120 Ma and 1080 Ma. This stage of transport was followed by out‐of‐sequence thrusting and further convergence along successively deeper, foreland‐propagating ductile thrust zones. A major episode of extension at ∼ 1020 Ma resulted in southeast directed transport of allochthonous rocks along the midcrustal Shawanaga shear zone. The final stage of convergence involved deformation and metamorphism in the Grenville Front Tectonic Zone at ∼ 1000–980 Ma. Peak metamorphism along most of the transect at 1065–1045 Ma followed initial transport of allochthonous rocks over the craton by 15–35 m.y. Regional cooling, which postdated peak metamorphism by >70 m.y., was probably delayed by the combined effects of late‐stage extension and convergence. Transport of allochthons at least 100 km over the craton was accomplished along a weak, migmatitic decollement; further propagation of the orogen into the craton followed partial melting and weakening of parautochthonous rocks below this decollement. Extensional deformation was associated with distributed ductile flow, the formation of regional transverse folds with axes parallel to the stretching direction, and reactivation of the allochthon‐parautochthon thrust boundary as an extensional decollement. The extensional lower crustal flow was likely the primary cause of the subhorizontal attitude of many structures and seismic reflectors in this part of the Central Gneiss Belt.
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SL6 includes terranes and domains of the Composite Arc and Frontenac-Adirondack belts.
“In the northwestern part of the Grenville Province in Ontario (Fig. 2), the architecture, metamorphism and interrelationships of terranes and domains have been investigated in detail and the threefold lithotectonic subdivision shown in Fig. 1 has been refined into at least six structural levels (SLs; e.g., Culshaw et al. 1997; Ketchum and Davidson 2000), with the lowest (SL1) being adjacent to the”
From The High Pressure belt in the Grenville Province: architecture, timing, and exhumation (2002) · cites this paper as Culshaw et al. 1997
The Figure 2 caption (page unavailable) identifies the Parry Sound domain as originally associated with CMB magmatic arcs, supporting the Composite Arc portion in broad terms. The copy does not identify an SL6 or place Frontenac-Adirondack terranes and domains within it; searches for “SL6” and “Frontenac Adirondack” did not establish those parts of the claim. (LLM, conf=0.78)
Experimental — accuracy not yet measuredSL1 is adjacent to the Grenville Front.
“In the northwestern part of the Grenville Province in Ontario (Fig. 2), the architecture, metamorphism and interrelationships of terranes and domains have been investigated in detail and the threefold lithotectonic subdivision shown in Fig. 1 has been refined into at least six structural levels (SLs; e.g., Culshaw et al. 1997; Ketchum and Davidson 2000), with the lowest (SL1) being adjacent to the”
From The High Pressure belt in the Grenville Province: architecture, timing, and exhumation (2002) · cites this paper as Culshaw et al. 1997
Section 2.2 (page unavailable) says the Grenville Front Tectonic Zone abuts the foreland along the Grenville Front, supporting the location of the frontmost zone. The paper does not identify that zone as “SL1” or use the citing document’s structural-level numbering, so it does not establish the specific SL1 attribution. (LLM, conf=0.78)
Experimental — accuracy not yet measuredIn the northwestern part of the Grenville Province in Ontario, the threefold lithotectonic subdivision shown in Fig. 1 has been refined into at least six structural levels (SLs).
“In the northwestern part of the Grenville Province in Ontario (Fig. 2), the architecture, metamorphism and interrelationships of terranes and domains have been investigated in detail and the threefold lithotectonic subdivision shown in Fig. 1 has been refined into at least six structural levels (SLs; e.g., Culshaw et al. 1997; Ketchum and Davidson 2000), with the lowest (SL1) being adjacent to the”
From The High Pressure belt in the Grenville Province: architecture, timing, and exhumation (2002) · cites this paper as Culshaw et al. 1997
The Introduction (page unavailable) describes the three major divisions of the Grenville Province in Ontario, then identifies the Grenville Front Tectonic Zone and five first-order subdivisions of the Central Gneiss Belt along the Georgian Bay transect. This supports a more detailed subdivision of the northwestern area, but the paper does not identify those six units as numbered structural levels (SLs). (LLM, conf=0.82)
Experimental — accuracy not yet measuredEclogite-facies relics, associated with pods and lenses of ultramafic and anorthositic rocks, are restricted mainly to high-strain zones between and within the terranes and domains.
“Eclogite-facies relics, associated with pods and lenses of ultramafic and anorthositic rocks, are restricted mainly to high-strain zones between and within the terranes and domains (Fig. 2; Davidson 1991, 1998; Culshaw et al. 1997).”
From The High Pressure belt in the Grenville Province: architecture, timing, and exhumation (2002) · cites this paper as Culshaw et al. 1997
Section 4.5 (page not provided) says relict eclogitic rocks are most common in shear zones, though not confined to them. Section 2.7 says they are commonly associated with anorthosite in major shear zones. The copy does not establish the claimed association with pods and lenses of ultramafic rocks. (LLM, conf=0.86)
Experimental — accuracy not yet measuredMuskoka domain underwent granulite-facies metamorphism during the Ottawa orogeny at c. 1080-1065 Ma, coeval with that in the adjacent Algonquin terrane.
“Muskoka domain underwent granulite-facies metamorphism during the Ottawa orogeny at c45 1080-1065 Ma (Culshaw et al. 1997; Timmermann et al. 1997), coeval with that in the adjacent Algonquin terrane.”
From The High Pressure belt in the Grenville Province: architecture, timing, and exhumation (2002) · cites this paper as Culshaw et al. 1997
Section 4.5 (page unavailable) says high-grade metamorphism did not affect Muskoka before approximately 1080 Ma and that Muskoka migmatites formed and deformed around 1080 Ma. It does not establish granulite-facies conditions in Muskoka, a 1080–1065 Ma interval for that domain, or coeval metamorphism in the adjacent Algonquin terrane. (LLM, conf=0.84)
Experimental — accuracy not yet measured
Upper amphibolite- and granulite-facies metamorphism in Parry Sound domain has been dated at c. 1160 Ma and c. 1120 Ma, predating that in the underlying Algonquin terrane, although retrogression to amphibolite-facies assemblages is widespread.
“Upper amphiboliteand granulite-facies metamorphism in Parry Sound domain has been dated at c45 1160 Ma and c45 1120 Ma (van Breemen et al. 1986; Tuccillo et al. 1992), predating that in the underlying Algonquin terrane, although retrogression to amphibolite-facies assemblages is widespread (Culshaw et al. 1997).”
From The High Pressure belt in the Grenville Province: architecture, timing, and exhumation (2002) · cites this paper as Culshaw et al. 1997
Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.
Experimental — accuracy not yet measuredThe pre-1300 Ma history of the Laurentian margin is absent in the Composite Arc and Frontenac-Adirondack belts.
“This pre-1300 Ma history of the Laurentian margin is absent in the Composite Arc and Frontenac-Adirondack belts (see also, e.g., Wodicka et al. 1996; Culshaw et al. 1997; Carr et al. 2000).”
From The High Pressure belt in the Grenville Province: architecture, timing, and exhumation (2002) · cites this paper as Culshaw et al. 1997
The Geological Setting (section 2.1; page unavailable) distinguishes the pre-1400 Ma Laurentian rocks of the Central Gneiss Belt from the post-1400 Ma composite arc system of the Central Metasedimentary Belt. This supports the distinction for the composite arcs, but the paper does not establish that pre-1300 Ma Laurentian-margin history is absent in the Frontenac-Adirondack belts. (LLM, conf=0.77)
Experimental — accuracy not yet measuredRetrogressed eclogite-facies gabbro and associated ultramafic and anorthositic rocks occur in highly strained bodies up to several tens of kilometres long and in tectonically disrupted pods, lenses, and boudins, especially along domain boundaries in the western Grenville Province.
“In the western Grenville Province, as noted earlier, retrogressed eclogite-facies gabbro and associated ultramafic and anorthositic rocks occur in highly strained bodies up to several tens of kilometres long and in tectonically disrupted pods, lenses, and boudins, especially along domain boundaries (Davidson 1991, 1998; Culshaw et al. 1997; Fig. 6A).”
From The High Pressure belt in the Grenville Province: architecture, timing, and exhumation (2002) · cites this paper as Culshaw et al. 1997
Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.
Experimental — accuracy not yet measuredTime of normal displacement on the Shawanaga shear zone in cross-section A has been dated at c. 1020 Ma.
“Time of normal displacement has been dated at c45 1020 Ma on Shawanaga shear zone in cross-section A (Culshaw et al. 1997; Ketchum et al. 1998)”
From The High Pressure belt in the Grenville Province: architecture, timing, and exhumation (2002) · cites this paper as Culshaw et al. 1997
The paper’s schematic tectonic reconstruction (section 4.5, page unavailable) places extension on the Shawanaga shear zone at approximately 1020 Ma, and its Figure 3 caption describes extensional shear there. It does not establish that the normal displacement itself was directly dated to 1020 Ma; the reconstruction explicitly calls the timing schematic. (LLM, conf=0.84)
Experimental — accuracy not yet measuredThe Paleoproterozoic lower crust underlying the southern Parautochthonous belt in the western Grenville Province was unusually ductile during the Ottawa orogeny, leading to widespread distributed flow in gneissic rocks during both compressional and extensional tectonism.
“In addition, the Paleoproterozoic lower crust underlying the southern Parautochthonous belt in the western Grenville Province was unusually ductile during the Ottawa orogeny, leading to widespread distributed flow in gneissic rocks during both compressional and extensional tectonism (Fig. 12C; Culshaw et al. 1994, 1997; Ketchum et al. 1998).”
From The High Pressure belt in the Grenville Province: architecture, timing, and exhumation (2002) · cites this paper as Culshaw et al. 1997
Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.
Experimental — accuracy not yet measuredEarly Ottawan out-of-sequence thrusting of the terranes overlying the HP belt occurred in the western Grenville Province.
“early Ottawan out-of-sequence thrusting of the terranes overlying the HP belt in the western Grenville Province”
From The High Pressure belt in the Grenville Province: architecture, timing, and exhumation (2002) · cites this paper as Culshaw et al. 1997
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Research works printed but not linked: 6
- Bethune, K.M., Evolution of the Grenville Front in the Tyson Lake area, southwest of Sudbury, Ontario, with emphasis on the tectonic significance of the the Sudbury diabase dykes, Ph.D. thesis, Queen's Univ., Kingston, Ontario, Can., 1993.
- Bethune, K.M., Structure and metamorphism of the Sudbury dykes in the Tyson Lake area, Ontario, Canada: New insights on the nature and timing of tectonism along the Grenville Front, Precambrian Res., in press, 1997.
- Burr, J.L., and S.D. Carr, Structural geometry and U-Pb geochronology near Lithoprobe seismic Line 32, Western Central Metasedimentary Belt, Grenville Province, Ontario: New results from high precision' U-Pb geochronology. Lithoprobe Abitibi- Grenville Project, Workshop Report, 59- 62, 1994.
- Ellis, S., C. Beaumont, R.A. Jamieson, and G. Quin!an, Continental collision including a weak zone -the vise model and its application to the Newfoundland Appalachians, Can. d. Earth. Sci., in press, 1997.
- Ketchum, J.W.F. Extensional shear zones and lithotectonic domains in the southwest Grenville orogen: Structure, metamor- phism, and U-Pb geochronology of the Central Gneiss Belt near Pointe-au-Baril, Ontario, Ph.D. thesis, Dalhousie Univ., Halifax, Nova Scotia, Canada, 1995.
- Wodicka, N., Middle Proterozoic evolution of the Parry Sound domain, southwestern Grenville orogen, Ontario, Structural, metamorphic, U/Pb and 4øAr/39Ar constraints, Ph.D. thesis, Dalhousie Univ., Halifax, Nova Scotia, Can., 1994.
Cited by
Sorted by citations
Dunn, S. R., Markley, M. J., Kotikian, M., Achenbach, K., Montanye, B., & Peck, W. H. (2019) · American Mineralogist · doi:10.2138/am-2019-6757 · Cited by 11 · see citing works
The High Pressure belt in the Grenville Province: architecture, timing, and exhumation
Rivers, T., Ketchum, J., Indares, A., & Hynes, A. (2002) · Canadian Journal of Earth Sciences · doi:10.1139/e02-025 · Cited by 124 · see citing works
Self-citation
- Authors
- Culshaw, N. G., Jamieson, R. A., Ketchum, J. W. F., Wodicka, N., Corrigan, D., & Reynolds, P. H.
- Venue
- Tectonics
- Publisher
- American Geophysical Union (AGU)
- Published
- 1997-12
- Volume
- 16
- Issue
- 6
- Pages
- 966-982
- ISSN
- 0278-7407 (ISSN-L)
- 1944-9194
- OpenAlex
- W1964232945
- Cited by
- 108
- References
- 0
- Citations by year
- 2026: 2 · 2025: 2 · 2024: 4 · 2023: 1 · 2022: 5 · 2021: 1 · 2020: 1 · 2019: 5 · 2018: 3 · 2017: 6 · 2016: 5 · 2015: 8 · 2014: 5 · 2013: 4 · 2012: 2
- FWCI
- 4.74
- Type
- journal article
- Language
- en
- Open access
- green
- hdl.handle.net
- Locations
- Tectonics (publishedVersion)
- DalSpace (Dalhousie University) (submittedVersion)
- Funders
- Natural Sciences and Engineering Research Council of Canada
- Topics
- Physical Sciences › Earth and Planetary Sciences › Geophysics › Geological and Geochemical Analysis
- Physical Sciences › Earth and Planetary Sciences › Geology › Geological Studies and Exploration
- Physical Sciences › Earth and Planetary Sciences › Geology › Geological and Geophysical Studies
- Keywords
- Grenville orogeny, Central Gneiss Belt, crustal extension, décollement, thrusting, partial melting, migmatites, ductile flow, Laurentian craton, accretion
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