Isotopic mapping of the Allochthon Boundary Thrust in the Grenville Province of Ontario, Canada

Dickin, A. P.; Moretton, Katherine; North, Robert G.

doi:10.1016/j.precamres.2008.08.007

Cited by 24 publications

(27 citation statements)

References 20 publications

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“…The Pb-Pb slope age of ca. 1.74 Ga for the Suture Suite is consistent with the whole-rock Sm-Nd isochron age for the Paleoproterozoic terrane determined by Dickin et al [37]. It is also consistent with the age of Killarnean plutonism dated at 1742 ± 1.4 Ma by van Breemen and Davidson [24].…”

Section: Resultssupporting

confidence: 90%

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Pb Isotope Mapping of Paleoproterozoic Gneisses in the SW Grenville Province: Evidence for a Cryptic Continental Suture

Arcuri

Dickin

2018

Geosciences

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New whole-rock lead (Pb) isotope analyses are presented in this study for granitoid orthogneisses from the Southwest Grenville Province in Ontario and Western Quebec. These data are used to test the location of a cryptic Archean-Proterozoic suture proposed on the basis of neodymium (Nd) isotope mapping. Immediately south of the inferred suture boundary, Pb isotope results show a crustal component derived solely from a juvenile Paleoproterozoic mantle source. These data are distinctly different from the reworked Archean craton to the northwest and strongly support the boundary derived from Nd isotope data. Pb signatures in the Paleoproterozoic crust suggest a southerly increase in magmatic reworking due to intensive plutonism during the late Paleoproterozoic and early Mesoproterozoic periods. The accretion of a juvenile arc to the Archean margin during the Penokean event (ca. 1.85 Ga) would have triggered subduction-zone reversal and the development of a long-lived ensialic arc on the composite margin. This was expressed as a 1.75 Ga Killarnian magmatic event and subsequent early Mesoproterozoic magmatism. This tectonic model for the Southwest Grenville Province shows that its crustal evolution is consistent with the Paleoproterozoic Makkovik-Ketilidian Orogen of Labrador and Southern Greenland. Hence, the application of whole-rock Pb isotope data in conjunction with Nd model ages provides data useful for mapping the extent of crustal terranes of differing age, which is essential for modeling the tectonic evolution of complex ancient accretionary orogens.

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Section: Resultssupporting

confidence: 90%

“…However, an average ca. 1.90 Ga Nd model age for crust south of the suture emphasizes the melting of mafic rock at the base of the Penokean arc rather than juvenile mantle-derived magmatism [17,37].…”

Section: Paleoproterozoic Evolution Of the Sw Grenville Provincementioning

confidence: 99%

Pb Isotope Mapping of Paleoproterozoic Gneisses in the SW Grenville Province: Evidence for a Cryptic Continental Suture

Arcuri

Dickin

2018

Geosciences

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“…However, the origins of the older components are different in the two regions. In Ontario, the older component is attributed to an accreted Palaeoproterozoic arc with geographically homogeneous Nd signatures that yield a 1.75 Ga Sm-Nd isochron [11], as described in the introduction. In contrast, the older component in the present study area was itself the product of earlier mixing, demonstrated by its highly variable model age structure.…”

Section: Nd Isotope Resultsmentioning

confidence: 99%

“…However, the situation in Ontario is quite different, because "primary Palaeoproterozoic crust" (with an average TDM age of 1.9 Ga) is here fringed by the Algonquin ensialic arc mixing zone, which was itself reworked by Elzevirian continental arc magmatism. Therefore, in Ontario, the edge of primary Palaeoproterozoic crust is best approximated by a 1.8 Ga demarcation line, which also corresponds to the location of the ABT [11]. In contrast, a 1.55 Ga age cut-off runs through the middle of the mixing line in the Algonquin ramp, as indicated by the black horizontal bar in Figure 4.…”

Section: Discussionmentioning

confidence: 96%

“…In this area, Archean crust reaches as far as 150 km SE of the Grenville Front, but in some areas, it has been strongly reworked by later plutonism, and in other areas, it is covered by metasedimentary rocks that sampled material with mixed sources [3]. In some areas, Archean crust is over-ridden by the allochthonous belt, which forms large nappe lobes, but elsewhere, Archean crust is sutured against an accreted Palaeoproterozoic arc terrane with homogeneous Nd isotope signatures that gave rise to a 53 point Sm-Nd isochron age of 1.75 ± 0.05 Ga [11].…”

Section: Regional Geological Backgroundmentioning

confidence: 99%

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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

Zelek

Dickin

2013

Geosciences

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Over 100 new Nd isotope analyses for the central Grenville Province in the Parent-Clova region of Quebec help fill a major gap in understanding the crustal accretion history of the province. Nd model ages show that the Parent-Clova region consists of three crustal blocks: the Archean parautochthon in the north; a central block with mixed ages interpreted as an ensialic arc; and a southerly block forming an extension of the Mesoproterozoic Quebecia arc terrane. The Allochthon Boundary Thrust is believed to define the edge of the Archean parautochthon, which is bordered for a distance of 300 km by the ensialic arc block, within which model ages decrease consistently away from the craton. A similar negative correlation between Nd model age and distance from the craton is seen in published data for the Algonquin terrane in Ontario, but with a lower range of model ages. These comparisons show that in the Parent-Clova region, a Mesoproterozoic ensialic arc was established directly on the Archean margin, but further west, the Mesoproterozoic arc was built on a younger margin consisting of accreted Palaeoproterozoic arc crust. The use of large Nd data sets allows these distinct regional growth patterns to become clear and, hence, allows an understanding of Mesoproterozoic crustal evolution in the province as a whole

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Utility of Detrital Zircon Grains From Upper Amphibolite Facies Rocks of the Grenville Supergroup, Adirondack Lowlands, Northeastern United States

Chiarenzelli

Kratzmann

Selleck

et al. 2017

Sediment Provenance

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Isotopic mapping of the Allochthon Boundary Thrust in the Grenville Province of Ontario, Canada

Cited by 24 publications

References 20 publications

Pb Isotope Mapping of Paleoproterozoic Gneisses in the SW Grenville Province: Evidence for a Cryptic Continental Suture

Pb Isotope Mapping of Paleoproterozoic Gneisses in the SW Grenville Province: Evidence for a Cryptic Continental Suture

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

Utility of Detrital Zircon Grains From Upper Amphibolite Facies Rocks of the Grenville Supergroup, Adirondack Lowlands, Northeastern United States

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