High‐pressure, high‐temperature rocks from the base of thick continental crust: Geology and age constraints from the Manicouagan Imbricate Zone, eastern Grenville Province

Indares, Aphrodite; Dunning, G. R.; Cox, R. A.; Gale, D.; Connelly, J. N.

doi:10.1029/98tc00373

Cited by 57 publications

(42 citation statements)

References 29 publications

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“…1.71-1.60 Ga arc magmatism and arc accretion; Gower andKrogh 2002a, 2002b;Gower et al 2008) crust in Labrador, easternmost Quebec, and Newfoundland. Some ages from smaller magmatic bodies in the Manicouagan area have also been reported (Connelly and Heaman 1993;Tucker and Gower 1994;Wasteneys et al 1997;Indares et al 1998;Gower and Krogh 2002a;Heaman et al 2004;Gower et al 2008). Evidence, although scattered, also exist for metamorphism and deformation associated with the Pinwarian event.…”

Section: Pinwarian Orogenymentioning

confidence: 84%

“…1350 to 1290 Ma (Ryan et al 1991;Gower and Krogh 2002a, and references therein). The Nain Plutonic Suite intruded north of the Grenville front, but coeval felsic magmatism has also been recorded from within the Grenville orogenic belt (Schärer et al 1986;Indares et al 1998). Early Geon 12 magmatism is volumetrically less important and has been attributed to distal back-arc magmatism by Rivers et al (2012).…”

Section: Middle Geons 14 To 12 Magmatismmentioning

confidence: 94%

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Pinwarian to Grenvillian magmatic evolution in the central Grenville Province: new constraints from ID–TIMS U–Pb ages and coupled Lu–Hf S–MC–ICP–MS data

et al. 2015

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Understanding the magmatic evolution of the rocks once comprising the hinterland of the Grenville Orogen through their Mesoproterozoic formation is a key to understanding the Grenvillian Orogeny as a whole. In this contribution, we present high-precision isotope dilution thermal ionization mass spectrometry (ID-TIMS) U-Pb and coupled solution multicollector inductively coupled plasma mass spectrometry (S-MC-ICP-MS) Lu-Hf zircon data from magmatic rocks occurring in the allochthonous belt of the Grenville Orogen in the central part of the Grenville Province. We document the presence of a large tract of Pinwarian crust represented by a 1497 ± 5 Ma granitic gneiss, as well as large late Geon 14 to early Geon 13 (1434 +7/−11, 1413 ± 12, 1393 ± 8, 1383 ± 1 Ma) magmatic complexes. One Grenvillian plutonic suite of 1015 ± 2 Ma that cross-cuts the host-rock metamorphic fabric has also been dated. This age provides a minimum age of Ottawan metamorphism in the region. The Hf-isotopic data show that the magmatic rocks of Geons 14 and 13 had mixed mantle and crustal sources compatible with intrusion in a supra-subduction setting as is also supported by the whole-rock geochemical data presented. Emplacement of the magmatic rocks occurred in settings varying from a distal margin arc to a contractional and extensional continental arc. Grenvillian-aged magmatism is more ambiguous, but our data indicate that rocks as young as ca. 1015 Ma may have formed in an ensialic setting.Résumé : La compréhension de l'évolution magmatique des roches qui composaient jadis l'arrière-pays de l'orogène de Grenville durant leur formation au Mésoprotérozoïque constitue la clé pour comprendre l'orogène de Grenville dans son ensemble. Dans cet article, nous présentons des données de grande précision d'analyses par dilution isotopique et spectrométrie de masse à thermoionisation (ID-TIMS) U-Pb et d'analyses isotopiques Lu-Hf, par une combinaison des techniques S-MC-ICP-MS, de zircons provenant de roches magmatiques se trouvant dans la ceinture allochtone de l'orogène de Grenville dans la partie centrale de la Province de Grenville. Nous documentons la présence d'une grande superficie de croûte (Pinwarien) représentée par un gneiss granitique 1497 ± 5 Ma et de vastes complexes magmatiques du géon 14 au début du géon 13 (1434 +7/−11, 1413 ± 12, 1393 ± 8, 1383 ± 1 Ma). Une suite plutonique (Grenville) de 1015 ± 2 Ma qui recoupe de manière transversale la fabrique métamorphique de la roche encaissante a aussi été datée. Cet âge fournit un âge minimum pour le métamorphisme ottavien dans la région. Les données isotopiques Hf montrent que les roches magmatiques des géons 14 et 13 provenaient de sources mélangées dans le manteau et dans la croûte, ce qui est compatible avec une intrusion dans un environnement de suprasubduction et aussi supporté par les données géochimiques sur la roche entière présentées. La mise en place des roches magmatiques a eu lieu dans des environnements variant d'un arc marginal distal à un arc continental de contraction et d'extens...

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Section: Pinwarian Orogenymentioning

confidence: 84%

Section: Middle Geons 14 To 12 Magmatismmentioning

confidence: 94%

Pinwarian to Grenvillian magmatic evolution in the central Grenville Province: new constraints from ID–TIMS U–Pb ages and coupled Lu–Hf S–MC–ICP–MS data

et al. 2015

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“…These two features are comparable to e.g. hightemperature northwestern parts of the Western Gneiss Region in the Scandinavian Caledonides (subducted continental margin; e.g., Griffin et al, 1985;Cuthbert et al, 2000;Hacker et al, 2010) or the highpressure belts in the Grenville Province of eastern Canada (large hot orogen; e.g., Davidson, 1990;Indares et al, 1998;Rivers, 2009;Rivers et al, 2012).…”

Section: Protolith Setting Character and Timing Of Eclogite Metamorpmentioning

confidence: 94%

Exhumation of an eclogite terrane as a hot migmatitic nappe, Sveconorwegian orogen

Möller

Andersson

Dyck

et al. 2015

Lithos

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We demonstrate a case of eclogite exhumation in a partially molten, low-viscosity fold nappe within high-grade metamorphosed crust in the Eastern Segment of the Sveconorwegian orogen. The nappe formed during tectonic extrusion, melt-weakening assisted exhumation and foreland-directed translation of eclogitized crust, and stalled at 35-40 km depth within the collisional belt. The eclogites are structurally restricted to a regional recumbent fold in which stromatic orthogneiss with pods of amphibolitized eclogite make up the core. Hightemperature mylonitic gneiss with remnants of kyanite eclogite (P N 15 kbar) composes a basal shear zone 50 km long and b 4 km wide. Heterogeneously sheared and partly migmatized augen gneiss forms a tectonostratigraphic marker in front of and beneath the nappe, and is in turn structurally enveloped by a composite sequence of orthogneisses and metabasites. The entire tectonostratigraphic pile underwent near-pervasive deformation and recrystallization under high-pressure granulite and upper amphibolite conditions. U-Pb SIMS metamorphic zircon ages of eclogite and stromatic orthogneiss constrain the time of eclogitization at 988 ± 6 Ma and 978 ± 7 Ma. Migmatization, concomitant deformation, and exhumation are dated at 976 ± 6 Ma, and crystallization of post-kinematic melt at 956 ± 7 Ma. Orthogneiss protoliths are dated at 1733 ± 11 and 1677 ± 10 Ma (stromatic gneiss) and 1388 ± 7 Ma (augen gneiss in footwall), demonstrating origins indigenous to the Eastern Segment. Eclogitization and exhumation were coeval with the Rigolet phase of the Grenvillian orogeny, reflecting the late stage of continental collision during construction of the supercontinent Rodinia.

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“…Transported rocks can be divided structurally into a lower unit of reworked Proterozoic (Labradorian and Pinwarian) rocks that probably belonged to the Laurentian margin before the Grenvillian orogeny (herein called the High-Pressure terranes, cf. Indares et al (1998), because they appear to have been deeply buried during the Ottawan pulsesee below) and three overlying units of suspect provenance, exhibiting Elzevirian tectonism -the Composite Arc allochthon, the Frontenac-Adirondack Lowlands allochthon, and the Morin-Adirondack Highlands allochthon (Fig. 1, cf.…”

Section: The Abitibi Region and The Superior Provincementioning

confidence: 96%

The Lithoprobe Abitibi-Grenville transect: two billion years of crust formation and recycling in the Precambrian Shield of Canada

Ludden¹,

Hynes²

2000

Can. J. Earth Sci.

108

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We summarize the results of Lithoprobe studies in the Neoarchean southeastern Superior Province and the Mesoproterozoic Grenville Province, in the southeastern Precambrian Shield of Canada, through two composite crosssections based on seismic reflection data, which define dramatically different styles of crust formation and tectonic accretion in the Neoarchean and Mesoproterozoic. In the Neoarchean, the structures at the surface are steep, with discontinuous and flatter structures at depth, much of the crust appears to be juvenile, and the predominant process of crustal growth is inferred to have been subduction-accretion of primitive crust in a prograding arc system. In the Mesoproterozoic, surface structures are shallow and the seismic character of the crust is continuous over the entire cross-section. Archean parautochthonous rocks and reworked Archean crust comprise a very significant proportion of the preserved crust in the Mesoproterozoic and provided the backstop to the Grenvillian orogeny, resulting in the exhumation of crustal rocks formed at high pressures. Preservation of Neoarchean crust, including a thickened lithosphere in the Superior Province, in contrast to its general destruction in younger orogens, may well relate to a unique thermal regime at this time on Earth.Résumé : Nous résumons les résultats des études Lithoprobe dans la partie sud-est néoarchéenne de la province du Supérieur et dans la province mésoprotérozoïque du Grenville, dans le sud-est du Bouclier canadien précambrien, par deux sections composites de coupes basées sur des données de réflexion qui définissent des styles radicalement diffé-rents de formation crustale et d'accrétion tectonique au Néoarchéen et au Mésoprotérozoïque. Au Néoarchéen, les structures à la surface sont abruptes avec des structures discontinues et plus aplaties en profondeur; une grande partie de la croûte semble peu évoluée et on suppose que le procédé dominant de croissance crustale serait l'accrétion-subduction de la croûte d'origine dans un système d'arc accrétionnaire. Au Mésoprotérozoïque, les structures de surface sont peu profondes et le caractère séismique de la croûte est continu sur toute la coupe. Des roches parautochtones et la croûte archéenne retravaillée comprennent une très grande proportion de la croûte préservée au Mésoprotérozoïque et fournissent une butée à l'orogène grenvillien; cela a comme résultat une exhumation de roches crustales formées à hautes pressions. Dans la province du Supérieur, la préservation de la croûte néoachéenne, incluant une lithosphère épaisse, contrairement à sa destruction générale lors des orogènes plus jeunes, peut bien être reliée à un régime thermal unique à cet époque sur la Terre.[Traduit par la Rédaction] Ludden and Hynes 476

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High‐pressure, high‐temperature rocks from the base of thick continental crust: Geology and age constraints from the Manicouagan Imbricate Zone, eastern Grenville Province

Abstract: Abstract.The

Cited by 57 publications

References 29 publications

Pinwarian to Grenvillian magmatic evolution in the central Grenville Province: new constraints from ID–TIMS U–Pb ages and coupled Lu–Hf S–MC–ICP–MS data

Pinwarian to Grenvillian magmatic evolution in the central Grenville Province: new constraints from ID–TIMS U–Pb ages and coupled Lu–Hf S–MC–ICP–MS data

Exhumation of an eclogite terrane as a hot migmatitic nappe, Sveconorwegian orogen

The Lithoprobe Abitibi-Grenville transect: two billion years of crust formation and recycling in the Precambrian Shield of Canada

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