Plutonic ages and tectonic setting of the Algonquin and Muskoka allochthons, Central Gneiss Belt, Grenville Province, Ontario

The Central Gneiss Belt comprises parautochthonous gneisses overlain by northwest-transported allochthonous terranes originating from the pre-Grenvillian Laurentian margin or from farther outboard as inferred for the Parry Sound allochthon. In the Huntsville region, orthogneisses of the Algonquin allochthon yielded U-Pb zircon igneous crystallization ages at 1444 +12-8, 1442 +9-8, and 1432 +54-98 Ma. In absence of direct evidence for older intrusions, the association of these plutonic rocks with gneisses giving Nd crustal residence ages of ca. 1.7 Ga sets the Algonquin allochthon apart from the underlying parautochthon, and from the overlying Muskoka allochthon. Orthogneisses from the latter also give zircon igneous ages at 1453 ± 6 Ma and 1427 +16-13 Ma, with no older memory. These ages closely correspond to the Nd model ages of associated gneisses, testifying to the juvenile nature of this terrane. Plutonic ages from the Algonquin and Muskoka allochthons are older than those of the Parry Sound allochthon to the northwest, thereby confirming its exotic nature. The importance, distribution, and nature of 1475-1410 Ma plutonism down structural section from the juvenile Muskoka allochthon, via the more mature Algonquin allochthon, into the parautochthon and Grenville foreland, testify to the development of an ensialic arc along that part of the Laurentian margin tectonically incorporated in the Central Gneiss Belt. Furthermore, the age and structural relationship require Grenvillian break-back thrust reactivation to account for the high structural position of the Muskoka allochthon, which was part of the Laurentian ramp during overthrusting of the younger and farther travelled Parry Sound allochthon.

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Mafic and ultrapotassic rocks from the Canyon domain (central Grenville Province): geochemistry and tectonic implications

Canadian Journal of Earth Sciences ◽

10.1139/e11-065 ◽

2012 ◽

Vol 49 (2) ◽

pp. 412-433 ◽

Cited By ~ 7

Author(s):

Carolina Valverde Cardenas ◽

Aphrodite Indares ◽

George Jenner

Keyword(s):

Tectonic Setting ◽

Source Region ◽

Crustal Contamination ◽

Granulite Facies ◽

Grenville Province ◽

Mafic Rocks ◽

Isotopic Signatures ◽

Late Evolution ◽

Grenvillian Orogeny ◽

Laurentian Margin

The Canyon domain and the Banded complex in the Manicouagan area of the Grenville Province preserve a record of magmatic activity from ∼1.4 to 1 Ga. This study focuses on 1.4–1.2 Ga mafic rocks and 1 Ga ultrapotassic dykes. Geochemistry and Sm–Nd isotopic signatures were used to constrain the origin of these rocks and evaluate the changing role of the mantle with time and tectonic setting from the late evolution of the Laurentian margin to the Grenvillian orogeny, in the Manicouagan area. The mafic rocks include layers inferred to represent flows, homogeneous bodies in mafic migmatite, and deformed dykes, all of which were recrystallized under granulite-facies conditions during the Grenvillian orogeny. In spite of the complexities inherent in these deformed and metamorphosed mafic rocks, we were able to recognize suites with distinctive geochemical and isotopic signatures. Integration of this data along with available ages is consistent with a 1.4 Ga continental arc cut by 1.2 Ga non-arc basalts derived from depleted asthenospheric mantle, with varied degrees of crustal contamination and inferred to represent magmatism in an extensional environment. The 1 Ga ultrapotassic dykes postdate the Grenvillian metamorphism. They are extremely enriched in incompatible elements, have negative Nb anomalies, relatively unradiogenic Sr-isotopic compositions (initial 87Sr/86Sr ~ 0.7040) and εNd –3 to –15. Some dykes have compositional characteristics consistent with derivation from the mantle, ruling out crustal contamination as a major process in their petrogenesis. The most likely source region for the ultrapotassic dykes is a metasomatized subcontinental lithospheric mantle, with thermal input from the asthenosphere in association with post-orogenic delamination.

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Amphibolites of the Shawanaga domain, Central Gneiss Belt, Grenville Province, Ontario: tectonic setting and implications for relations between the Central Gneiss Belt and Midcontinental USA

Precambrian Research ◽

10.1016/s0301-9268(01)00201-7 ◽

2002 ◽

Vol 113 (1-2) ◽

pp. 65-85 ◽

Cited By ~ 17

Author(s):

Nicholas Culshaw ◽

Jaroslav Dostal

Keyword(s):

Tectonic Setting ◽

Grenville Province ◽

Central Gneiss Belt

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Petrology and geochemistry of the Gore-Gambella plutonic rocks: implications for magma genesis and the tectonic setting of the Pan-African Orogenic Belt of western Ethiopia

Journal of African Earth Sciences ◽

10.1016/s0899-5362(98)00070-0 ◽

1998 ◽

Vol 27 (3-4) ◽

pp. 397-416 ◽

Cited By ~ 16

Author(s):

Teklewold Ayalew ◽

Angelo Peccerillo

Keyword(s):

Tectonic Setting ◽

Orogenic Belt ◽

Magma Genesis ◽

Pan African ◽

Petrology And Geochemistry ◽

Plutonic Rocks ◽

Western Ethiopia

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A seismic-based cross-section of the Grenville Orogen in southern Ontario and western Quebec

Canadian Journal of Earth Sciences ◽

10.1139/e99-094 ◽

2000 ◽

Vol 37 (2-3) ◽

pp. 183-192 ◽

Cited By ~ 61

Author(s):

D J White ◽

D A Forsyth ◽

I Asudeh ◽

S D Carr ◽

H Wu ◽

...

Keyword(s):

Cross Section ◽

Seismic Refraction ◽

Shear Zones ◽

Tectonic Zone ◽

Grenville Province ◽

Crustal Layer ◽

Seismic Reflection Data ◽

Velocity Models ◽

Laurentian Margin ◽

Structural Boundary

A schematic crustal cross-section is presented for the southwestern Grenville Province based on reprocessed Lithoprobe near-vertical incidence seismic reflection data and compiled seismic refraction - wide-angle velocity models interpreted with geological constraints. The schematic crustal architecture of the southwest Grenville Province from southeast to northwest comprises allochthonous crustal elements (Frontenac-Adirondack Belt and Composite Arc Belt) that were assembled prior to ca. 1160 Ma, and then deformed and transported northwest over reworked rocks of pre-Grenvillian Laurentia and the Laurentian margin primarily between 1120 and 980 Ma. Reworked pre-Grenvillian Laurentia and Laurentian margin rocks are interpreted to extend at least 350 km southeast of the Grenville Front beneath all of the Composite Arc Belt. Three major structural boundary zones (the Grenville Front and adjacent Grenville Front Tectonic Zone, the Central Metasedimentary Belt boundary thrust zone, and the Elzevir-Frontenac boundary zone) have been identified across the region of the cross-section based on their prominent geophysical signatures comprising broad zones of southeast-dipping reflections and shallowing of mid-crustal velocity contours by 12-15 km. The structural boundary zones accommodated southeast over northwest crustal stacking at successively earlier times during orogeny (ca. 1010-980 Ma, 1080-1060 Ma, and 1170-1160 Ma, respectively). These shear zones root within an interpreted gently southeast-dipping regional décollement at a depth of 25-30 km corresponding to the top of a high-velocity lower crustal layer.

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Monazite U–Th–Pb geochronology of the Central Metasedimentary Belt Boundary Zone (CMBbz), Grenville Province, Ontario Canada

Canadian Journal of Earth Sciences ◽

10.1139/cjes-2018-0039 ◽

2018 ◽

Vol 55 (9) ◽

pp. 1063-1078 ◽

Cited By ~ 1

Author(s):

Michelle J. Markley ◽

Steven R. Dunn ◽

Michael J. Jercinovic ◽

William H. Peck ◽

Michael L. Williams

Keyword(s):

Shear Zone ◽

Crustal Thickening ◽

Boundary Zone ◽

Grenville Province ◽

Metamorphic History ◽

Crustal Thinning ◽

Tectonic Significance ◽

History Of ◽

Central Gneiss Belt ◽

Scale Shear

The Central Metasedimentary Belt boundary zone (CMBbz) is a crustal-scale shear zone that juxtaposes the Central Gneiss Belt and the Central Metasedimentary Belt of the Grenville Province. Geochronological work on the timing of deformation and metamorphism in the CMBbz is ambiguous, and the questions that motivate our study are: how many episodes of shear zone activity did the CMBbz experience, and what is the tectonic significance of each episode? We present electron microprobe data from monazite (the U–Th–Pb chemical method) to directly date deformation and metamorphism recorded in five garnet–biotite gneiss samples collected from three localities of the CMBbz of Ontario (West Guilford, Fishtail Lake, and Killaloe). All three localities yield youngest monazite dates ca. 1045 Ma; most of the monazite domains that yield these dates are high-Y rims. In comparison with this common late Ottawan history, the earlier history of the three CMBbz localities is less clearly shared. The West Guilford samples have monazite grain cores that show older high-Y domains and younger low-Y domains; these cores yield a prograde early Ottawan (1100–1075 Ma) history. The Killaloe samples yield a well-defined prograde, pre- to early Shawinigan history (i.e., 1220–1160 Ma) in addition to some evidence for a second early Ottawan event. In other words, the answers to our research questions are: three events; a Shawinigan event possibly associated with crustal thickening, an Ottawan event possibly associated with another round of crustal thickening, and a late Ottawan event that resists simple interpretation in terms of metamorphic history but that coincides chronologically with crustal thinning at the base of an orogenic lid.

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New insights into the geologic evolution of the Grenvillian Trenton Prong inlier, Central Appalachian Piedmont, USA

Canadian Journal of Earth Sciences ◽

10.1139/cjes-2019-0140 ◽

2020 ◽

Vol 57 (7) ◽

pp. 840-854

Author(s):

Richard A. Volkert

Keyword(s):

Tectonic Setting ◽

Hanging Wall ◽

Sediment Source ◽

Slow Cooling ◽

Grenville Province ◽

Magmatic Arc ◽

Metamorphic History ◽

Arc Setting ◽

Appalachian Piedmont ◽

Back Arc

New geochemical and 40Ar/39Ar hornblende and biotite data from the Grenvillian Trenton Prong inlier provide the first constraints for the identification of lithotectonic units, their tectonic setting, and their metamorphic to post-metamorphic history. Gneissic tonalite, diorite, and gabbro compose the Colonial Lake Suite magmatic arc that developed along eastern Laurentia prior to 1.2 Ga. Spatially associated low- and high-TiO2 amphibolites were formed from island-arc basalt proximal to the arc front and mid-ocean ridge basalt-like basalt in a back-arc setting, respectively. Supracrustal paragneisses include meta-arkose derived from a continental sediment source of Laurentian affinity and metagraywacke and metapelite from an arc-like sediment source deposited in a back-arc basin, inboard of the Colonial Lake arc. The Assunpink Creek Granite was emplaced post-tectonically as small bodies of peraluminous syenogranite produced through partial melting of a subduction-modified felsic crustal source. Prograde mineral assemblages reached granulite- to amphibolite-facies metamorphic conditions during the Ottawan phase of the Grenvillian Orogeny. Hornblende 40Ar/39Ar ages of 935–923 Ma and a biotite age of 868 Ma record slow cooling in the northern part of the inlier following the metamorphic peak. Elsewhere in the inlier, biotite 40Ar/39Ar ages of 440 Ma and 377–341 Ma record partial to complete thermal resetting or new growth during the Taconian and Acadian orogens. The results of this study are consistent with the Trenton Prong being the down-dropped continuation of the Grenvillian New Jersey Highlands on the hanging wall of a major detachment fault. The Trenton Prong therefore correlates to other central and northern Appalachian Grenvillian inliers and to parts of the Grenville Province proper.

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Detrital zircon populations of the eastern Laurentian margin in the Appalachians

Geology ◽

10.1130/g48012.1 ◽

2020 ◽

Author(s):

Yvette D. Kuiper ◽

Christopher Hepburn

Keyword(s):

United States ◽

Detrital Zircon ◽

Orogenic Belt ◽

Grenville Province ◽

Zircon Age ◽

Zircon Population ◽

Middle Ordovician ◽

Archean Crust ◽

Laurentian Margin

Newly compiled U-Pb detrital zircon data from eight geographic domains along the eastern Laurentian margin from Newfoundland (Canada) to Alabama (United States) show a highly consistent signature along strike, with only minor local variations. The Precambrian signature is characterized by a small ca. 2.7 Ga population and a major ca. 1.9–0.9 Ga population that peaks at ca. 1.2–1.0 Ga. Detrital zircon populations are from Laurentian Archean crust (ca. 2.7 Ga population), Paleoproterozoic orogens (ca. 1.9–1.6 Ga), the Granite-Rhyolite Province (ca. 1.5–1.4 Ga), and the Elzevir terrane and Grenville Province (ca. 1.3–0.9 Ga). The Mesoproterozoic populations vary in size depending on proximity to the ca. 1.5–1.4 Ga Granite-Rhyolite Province, the ca. 1245–1225 Ma Elzevir terrane, and the ca. 1.2–0.9 Ga Grenville Province. A middle Ordovician zircon population varies in size along strike depending on input from the Taconic orogenic belt, but it is strongest in the northern Appalachians. Because of the general along-strike consistency in detrital zircon age populations, the compilation of all 7534 concordant U-Pb detrital zircon data can be used in future U-Pb detrital zircon studies as an indicator for eastern Laurentian margin sources.

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Character and tectonic setting of plutonic rocks in the Gällivare area, northern Norrbotten, Sweden

GFF ◽

10.1080/11035897.2018.1526209 ◽

2018 ◽

Vol 141 (1) ◽

pp. 1-20

Author(s):

Zmar Sarlus ◽

Olof Martinsson ◽

Tobias E. Bauer ◽

Christina Wanhainen ◽

Joel B. H. Andersson ◽

...

Keyword(s):

Tectonic Setting ◽

Plutonic Rocks

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Mantle influence of syn- to late-Grenvillian alkaline magmatism in the Grenville Province: causes and implications

Canadian Journal of Earth Sciences ◽

10.1139/cjes-2016-0135 ◽

2017 ◽

Vol 54 (3) ◽

pp. 263-277 ◽

Cited By ~ 4

Author(s):

Lars Eivind Augland ◽

Abdelali Moukhsil ◽

Fabien Solgadi

Keyword(s):

Orogenic Belt ◽

Alkaline Magmatism ◽

Magmatic Evolution ◽

Grenville Province ◽

Geochemical Composition ◽

Magmatic Rocks ◽

Grenville Orogeny ◽

Slab Breakoff ◽

Arc Setting ◽

Laurentian Margin

Several features of Geon 10 magmatic evolution in the Grenville Orogenic Belt is difficult to reconcile with generally accepted models of protracted (ca. 100 Myr) continent–continent collision during the Grenville Orogeny. Particularly the presence of (partly) mantle-derived magmatic rocks, some with subduction signatures, intruded during the inferred climax of the orogeny, is not well accounted for in existing models. We present new geochemical, Lu–Hf isotopic and U–Pb geochronological data from three alkaline composite plutons in Quebec, Canada, that give important clues to the tectono-magmatic evolution from ca. 1040 to 1000 Ma of the Grenville Laurentian margin. The oldest pluton, emplaced at ca. 1038 Ma, has a geochemical composition compatible with derivation in an arc setting by partial melting of subcontinental lithospheric mantle. The two youngest plutons, emplaced at ca. 1014 and 1009 Ma, respectively, have typical within-plate geochemical signatures showing no obvious influence of subduction. The new and existing data indicate that much of the Grenville Laurentian margin experienced ensialic magmatism through large parts of Geon 10, an observation calling for alternative models to the existing to explain the Geon 10 evolution of the Grenville Orogenic Belt. We propose a model where Ottawan metamorphism and magmatism resulted from accretion of terranes and continued subduction beneath Laurentia until late Geon 10. Late Geon 10 magmatism could have been related to slab breakoff prior to or at the onset of a late Geon 10 collisional event, which has also been recently proposed based on paleomagnetic arguments.

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