U–Pb geochronology of the Mazinaw terrane, an imbricate segment of the Central Metasedimentary Belt, Grenville Province, Ontario

1995 ◽  
Vol 32 (7) ◽  
pp. 959-976 ◽  
Author(s):  
Fernando Corfu ◽  
R. Michael Easton
Keyword(s):  
Detrital Zircon ◽  
Volcanic Rocks ◽  
Early Period ◽  
Amphibolite Facies ◽  
Crustal Thickening ◽  
Metamorphic Zircon ◽  
Grenville Province ◽  
Marginal Basin ◽  
Lake Formation ◽  
Northern Segment

The Mazinaw terrane, in the Central Metasedimentary Belt of the Grenville Province comprises, volcanic, sedimentary, and plutonic rocks that were intensely folded and faulted, and metamorphosed to as high as upper amphibolite facies. U–Pb geochronology establishes an early period of magmatism and sedimentation at about 1280–1240 Ma, probably in a marginal basin setting, and a multistage rhetamorphic evolution in the period between 1100 and 980 Ma, which was probably related to crustal thickening by imbrication during compression and wedging of the terrane. Some of the earliest magmatism formed calc-alkalic volcanic rocks of Kashwakamak Formation at 1276 ± 2 Ma. An associated sedimentary assemblage was intruded by the Helena trondhjemite stock at 1267 ± 5 Ma. A younger succession, formed between 1250 and 1240 Ma, includes the bimodal volcanic Mazinaw Lake Formation, alaskitic granites of the Norway Lake and Abinger plutons, and a granodioritic gneiss phase of the Cross Lake pluton. These units were covered unconformably by the Flinton Group sometime after 1150 Ma, as defined by published detrital zircon data. A northern segment of the Mazinaw terrane underwent deformation and metamorphism accompanied by the emplacement of granitic pegmatites in the period between 1100 and 1050 Ma. In contrast, metamorphism and deformation occurred significantly later in central domains, as shown by several metamorphic zircon populations grown at about 1040–1030, 1020, and 1010–1000 Ma, by pegmatite emplacement at about 980 Ma, and titanite ages of 1010–960 Ma. Younger rutile ages of about 915 Ma may reflect uplift of the terrane. Some rutile also appears to record the latest Proterozoic faulting and mafic diking related to formation of the Ottawa-Bonnechere graben at about 600 Ma.

The Central Slave Basement Complex, Part I: its structural topology and autochthonous cover

1999 ◽  
Vol 36 (7) ◽  
pp. 1083-1109 ◽  
Author(s):  
Wouter Bleeker ◽  
John WF Ketchum ◽  
Valerie A Jackson ◽  
Michael E Villeneuve
Keyword(s):  
Detrital Zircon ◽  
Hanging Wall ◽  
Volcanic Rocks ◽  
Iron Formation ◽  
Structural Topology ◽  
Banded Iron Formation ◽  
Basement Complex ◽  
South Central ◽  
Slave Province ◽  
Lake Formation

New field and geochronological data are used to define the distribution of Mesoarchean basement rocks in the south-central Slave Province. This distribution reflects a single contiguous basement terrane that we propose to call the Central Slave Basement Complex. It shows a structural topology that is internally consistent and compatible with known regional folding and faulting events. A sample of a proposed basement gneiss below the Courageous Lake greenstone belt, central Slave Province, has been dated by U-Pb methods and yields an age of 3325 ± 8 Ma, consistent with the new basement distribution. This sample also contains 2723 ± 3 Ma metamorphic zircon and ca. 2680 Ma titanite. The Central Slave Basement Complex is overlain by a thin, discontinuous, but distinctive cover sequence that includes minor volcanic rocks, clastic sedimentary rocks, and banded iron formation. All previously known and some new occurrences of this distinctive cover sequence occur in the immediate stratigraphic hanging wall of the Central Slave Basement Complex, locally overlying a preserved in situ unconformity. We propose to call this post-2.93 Ga cover sequence the Central Slave Cover Group. It is perhaps best typified by detrital chromite-bearing, fuchsitic quartzites. Formal formation names are proposed for the spatially separate occurrences of the Central Slave Cover Group. Detrital zircon ages are presented for one of the formations of the Central Slave Cover Group, the Patterson Lake Formation, which occurs on the western flank of a local basement culmination known as the Sleepy Dragon Complex. The detrital zircon data provide evidence for two discrete basement sources dated at ca. 2943 Ma and ca. 3147-3160 Ma. These detrital ages reinforce the depositional link between the Central Slave Cover Group and underlying crystalline rocks of the Central Slave Basement Complex.

La zone tectonique du front de Grenville à l'est de Louvicourt, Québec : exhumation de la croûte archéenne pendant l'orogénie grenvillienne

1995 ◽  
Vol 32 (11) ◽  
pp. 1899-1920 ◽  
Author(s):  
Alain Berclaz ◽  
Réjean Hébert ◽  
Michel Rocheleau
Keyword(s):  
Regional Metamorphism ◽  
Volcanic Rocks ◽  
Crustal Thickening ◽  
Coarse Grained ◽  
Superior Province ◽  
Reverse Fault ◽  
Tectonic Zone ◽  
Grenville Province ◽  
Vein Formation ◽  
Lower Temperature

The Grenville Front tectonic zone, East of Louvicourt in Quebec, defines a tectonometamorphic domain marked by the Grenville Front oriented North 50°, that is locally crosscut by a North 30° reverse fault, the Matchi-Manitou Fault. These tectonic accidents separate the central parts of the Superior Province to the northwest from the Grenville Province to the southeast. The Archean age, high-grade polymetamorphic sequences of the Grenville Province consist of paragneisses and migmatitic quartzofeldspathic gneisses associated to coarse-grained, anatectic pegmatitic veins, the whole containing shreds of two pyroxenes-bearing mafic gneisses. The metamorphic disequilibrium textures, the chemical analyses of the mineral phases, and the whole-rock chemistry of these sequences indicate that a strong crustal thickening, marked by the incorporation of shreds of volcanic rocks in the metasedimentary sequences, led to the granulitization of the lithologies and the quartzofeldspathic pegmatitic vein formation by fluid-absent partial melting of the surrounding migmatitic quartzofeldspathic gneisses under 750–825 MPa and 675–745 °C conditions. Subsequently, a higher pressure and slightly lower temperature episode (920–990 MPa and 625–750 °C) is at the origin of a development of secondary coronitic garnet around primary garnet. A late fluid is responsible for final retrograde reequilibrations in all the lithologies. All these successive events probably occurred during the Archean ages. During the Grenvillian orogeny (1.0 Ga), the thrusting movement with a strong sinistral component of the Grenvillian Province onto the Superior Province is characterized: (i) to the east of the Grenville Front, by the exhumation and the rotation of 9–12 km thick sequences of the Grenville Province; (ii) to the west of the Grenville Front, by the development of a 705–845 MPa and 570–605 °C medium-grade metamorphism that overprints the 400–565 MPa and 600–660 °C regional metamorphism of Kenorean age. Both metamorphic episodes define a 1–6 km width band made of biotite and garnet-bearing paragneisses.

scholarly journals Zircon Record of Supercontinent Amalgamation in Back-arc Volcanic Rocks

2020 ◽  
Author(s):  
Zhigang Zeng ◽  
Zuxing Chen ◽  
Yuxiang Zhang
Keyword(s):  
Continental Crust ◽  
Detrital Zircon ◽  
Okinawa Trough ◽  
Volcanic Rocks ◽  
Parental Magma ◽  
Crustal Thickening ◽  
The Okinawa Trough ◽  
Global Age ◽  
Back Arc

Abstract Episodic supercontinental amalgamation has profoundly influenced the evolution of the geosphere, hydrosphere, atmosphere and biosphere. However, the timing of supercontinent formation has mainly been constrained by the global age spectra of detrital zircon. Here, we show that the zircons in back-arc volcanic rocks not only reflect the evolution of local magmatism but also contain a record of global continental amalgamation events. We found that the young (<100 ka) zircons in volcanic rocks from the Okinawa Trough have old (108 Ma to 2.7 Ga) inherited zircon, which were captured as the magma ascended through the rifting continental crust. Moreover, the ages of the inherited zircons correspond to five supercontinent amalgamation events. Specifically, the Archaean inherited zircons, which have positive ɛHf(t) and low δ18O values, correspond to the formation of juvenile global continental crust. In contrast, the negative ɛHf(t) and high δ18O values of post-Archaean inherited zircons indicate that their parental magma contained recycled, old crust due to the enhanced crustal thickening and crust-mantle interactions during supercontinent assembly. Therefore, inherited zircons in back-arc volcanic rocks not only reflect the evolution of local magmatism but also contain a record of global supercontinental amalgamation events.

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

2018 ◽  
Vol 55 (9) ◽  
pp. 1063-1078 ◽  
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.

scholarly journals Crustal thickness of the Grenville orogen: A Mesoproterozoic Tibet?

Geology ◽  
2021 ◽  
Author(s):  
Adam Brudner ◽  
Hehe Jiang ◽  
Xu Chu ◽  
Ming Tang
Keyword(s):  
Crustal Thickness ◽  
Detrital Zircons ◽  
Crustal Thickening ◽  
Geochemical Data ◽  
Geochronological Data ◽  
Grenville Province ◽  
Crustal Thinning ◽  
Paleoenvironmental Evolution ◽  
Orogenic Plateau ◽  
St Lawrence River

The Grenville Province on the eastern margin of Laurentia is a remnant of a Mesoproterozoic orogenic plateau that comprised the core of the ancient supercontinent Rodinia. As a protracted Himalayan-style orogen, its orogenic history is vital to understanding Mesoproterozoic tectonics and paleoenvironmental evolution. In this study, we compared two geochemical proxies for crustal thickness: whole-rock [La/Yb]N ratios of intermediate-to-felsic rocks and europium anomalies (Eu/Eu*) in detrital zircons. We compiled whole-rock geochemical data from 124 plutons in the Laurentian Grenville Province and collected trace-element and geochronological data from detrital zircons from the Ottawa and St. Lawrence River (Canada) watersheds. Both proxies showed several episodes of crustal thickening and thinning during Grenvillian orogenesis. The thickest crust developed in the Ottawan phase (~60 km at ca. 1080 Ma and ca. 1045 Ma), when the collision culminated, but it was still up to 20 km thinner than modern Tibet. We speculate that a hot crust and several episodes of crustal thinning prevented the Grenville hinterland from forming a high Tibet-like plateau, possibly due to enhanced asthenosphere-lithosphere interactions in response to a warm mantle beneath a long-lived supercontinent, Nuna-Rodinia.

Accelerating exhumation in the Eocene North American Cordilleran hinterland: Implications from detrital zircon (U-Th)/(He-Pb) double dating

2019 ◽  
Vol 132 (1-2) ◽  
pp. 198-214 ◽  
Author(s):  
Andrew S. Canada ◽  
Elizabeth J. Cassel ◽  
Daniel F. Stockli ◽  
M. Elliot Smith ◽  
Brian R. Jicha ◽  
...  
Keyword(s):  
North American ◽  
Detrital Zircon ◽  
Sedimentary Basins ◽  
Metamorphic Core Complex ◽  
Crustal Thickening ◽  
Sediment Provenance ◽  
Core Complex ◽  
Extensional Faulting ◽  
Lag Times ◽  
Metamorphic Core

AbstractBasins in orogenic hinterlands are directly coupled to crustal thickening and extension through landscape processes and preserve records of deformation that are unavailable in footwall rocks. Following prolonged late Mesozoic–early Cenozoic crustal thickening and plateau construction, the hinterland of the Sevier orogen of western North America underwent late Cenozoic extension and formation of metamorphic core complexes. While the North American Cordillera is one of Earth’s best-studied orogens, estimates for the spatial and temporal patterns of initial extensional faulting differ greatly and thus limit understanding of potential drivers for deformation. We employed (U-Th)/(He-Pb) double dating of detrital zircon and (U-Th)/He thermochronology of detrital apatite from precisely dated Paleogene terrestrial strata to quantify the timing and magnitude of exhumation and explore the linkages between tectonic unroofing and basin evolution in northeastern Nevada. We determined sediment provenance and lag time evolution (i.e., the time between cooling and deposition, which is a measure of upper-crustal exhumation) during an 8 m.y. time span of deposition within the Eocene Elko Basin. Fluvial strata deposited between 49 and 45 Ma yielded Precambrian (U-Th)/He zircon cooling ages (ZHe) with 105–740 m.y. lag times dominated by unreset detrital ages, suggesting limited exhumation and Proterozoic through early Eocene sediment burial (&lt;4–6 km) across the region. Minimum nonvolcanic detrital ZHe lag times decreased to &lt;100 m.y. in 45–43 Ma strata and to &lt;10 m.y. in 43–41 Ma strata, illustrating progressive and rapid hinterland unroofing in Eocene time. Detrital apatite (U-Th)/He ages present in ca. 44 and 39 Ma strata record Eocene cooling ages with 1–20 m.y. lag times. These data reflect acceleration of basement exhumation rates by &gt;1 km/m.y., indicative of rapid, large-magnitude extensional faulting and metamorphic core complex formation. Contemporaneous with this acceleration of hinterland exhumation, syntectonic freshwater lakes developed in the hanging wall of the Ruby Mountains–East Humboldt Range metamorphic core complex at ca. 43 Ma. Volcanism driven by Farallon slab removal migrated southward across northeastern Nevada, resulting in voluminous rhyolitic eruptions at 41.5 and 40.1 Ma, and marking the abrupt end of fluvial and lacustrine deposition across much of the Elko Basin. Thermal and rheologic weakening of the lithosphere and/or partial slab removal likely initiated extensional deformation, rapidly unroofing deeper crustal levels. We attribute the observed acceleration in exhumation, expansion of sedimentary basins, and migrating volcanism across the middle Eocene to record the thermal and isostatic effects of Farallon slab rollback and subsequent removal of the lowermost mantle lithosphere.

scholarly journals Stitch in the ditch: Nutzotin Mountains (Alaska) fluvial strata and a dike record ca. 117–114 Ma accretion of Wrangellia with western North America and initiation of the Totschunda fault

Geosphere ◽  
2019 ◽  
Vol 16 (1) ◽  
pp. 82-110 ◽  
Author(s):  
Jeffrey M. Trop ◽  
Jeffrey A. Benowitz ◽  
Donald Q. Koepp ◽  
David Sunderlin ◽  
Matthew E. Brueseke ◽  
...  
Keyword(s):  
Fault Zone ◽  
Lower Cretaceous ◽  
Volcanic Rocks ◽  
Alkali Feldspar ◽  
Upper Jurassic ◽  
Sediment Provenance ◽  
Lake Formation ◽  
Beaver Lake ◽  
Channel Bar ◽  
Marine Basin

Abstract The Nutzotin basin of eastern Alaska consists of Upper Jurassic through Lower Cretaceous siliciclastic sedimentary and volcanic rocks that depositionally overlie the inboard margin of Wrangellia, an accreted oceanic plateau. We present igneous geochronologic data from volcanic rocks and detrital geochronologic and paleontological data from nonmarine sedimentary strata that provide constraints on the timing of deposition and sediment provenance. We also report geochronologic data from a dike injected into the Totschunda fault zone, which provides constraints on the timing of intra–suture zone basinal deformation. The Beaver Lake formation is an important sedimentary succession in the northwestern Cordillera because it provides an exceptionally rare stratigraphic record of the transition from marine to nonmarine depositional conditions along the inboard margin of the Insular terranes during mid-Cretaceous time. Conglomerate, volcanic-lithic sandstone, and carbonaceous mudstone/shale accumulated in fluvial channel-bar complexes and vegetated overbank areas, as evidenced by lithofacies data, the terrestrial nature of recovered kerogen and palynomorph assemblages, and terrestrial macrofossil remains of ferns and conifers. Sediment was eroded mainly from proximal sources of upper Jurassic to lower Cretaceous igneous rocks, given the dominance of detrital zircon and amphibole grains of that age, plus conglomerate with chiefly volcanic and plutonic clasts. Deposition was occurring by ca. 117 Ma and ceased by ca. 98 Ma, judging from palynomorphs, the youngest detrital ages, and ages of crosscutting intrusions and underlying lavas of the Chisana Formation. Following deposition, the basin fill was deformed, partly eroded, and displaced laterally by dextral displacement along the Totschunda fault, which bisects the Nutzotin basin. The Totschunda fault initiated by ca. 114 Ma, as constrained by the injection of an alkali feldspar syenite dike into the Totschunda fault zone. These results support previous interpretations that upper Jurassic to lower Cretaceous strata in the Nutzotin basin accumulated along the inboard margin of Wrangellia in a marine basin that was deformed during mid-Cretaceous time. The shift to terrestrial sedimentation overlapped with crustal-scale intrabasinal deformation of Wrangellia, based on previous studies along the Lost Creek fault and our new data from the Totschunda fault. Together, the geologic evidence for shortening and terrestrial deposition is interpreted to reflect accretion/suturing of the Insular terranes against inboard terranes. Our results also constrain the age of previously reported dinosaur footprints to ca. 117 Ma to ca. 98 Ma, which represent the only dinosaur fossils reported from eastern Alaska.

Geology and U–Pb geochronology of the Neoarchean Snare River terrane: tracking evolving tectonic regimes and crustal growth mechanisms

2005 ◽  
Vol 42 (6) ◽  
pp. 895-934 ◽  
Author(s):  
Venessa Bennett ◽  
Valerie A Jackson ◽  
Toby Rivers ◽  
Carolyn Relf ◽  
Pat Horan ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Detrital Zircon ◽  
Inductively Coupled Plasma ◽  
Granulite Facies ◽  
Crustal Thickening ◽  
Ionization Mass ◽  
Granulite Facies Metamorphism ◽  
Zircon Crystallization ◽  
Facies Metamorphism ◽  
Turbidite Sedimentation

U–Pb zircon crystallization ages determined by isotope dilution – thermal ionization mass spectrometry (ID–TIMS) and laser ablation microprobe – inductively coupled plasma – mass spectrometry (LAM–ICP–MS) for 13 intrusive units in the Neoarchean Snare River terrane (SRT) provide tight constraints on the timing of crust formation and orogenic evolution. Seven metaluminous plutons were emplaced over ~80 Ma from ca. 2674 to 2589 Ma, whereas six peraluminous bodies were emplaced in a ~15 Ma interval from ca. 2598 to 2585 Ma. A detrital zircon study yielded an age spectrum with peaks correlative with known magmatic events in the Slave Province, with the ca. 2635 Ma age of the youngest detrital zircon population providing a maximum estimate for the onset of sedimentation. This age contrasts with evidence for pre-2635 Ma sedimentation elsewhere in the SRT, indicating that sedimentation was protracted and diachronous. Evolution of the SRT can be subdivided into four stages: (i) 2674–2635 Ma — formation of a metaluminous protoarc in a tonalite–trondhjemite–granodiorite (TTG) – granite–greenstone tectonic regime (TR1) and coeval with early turbidite sedimentation; (ii) 2635–2608 Ma — continued turbidite sedimentation, D1/M1 juxtaposition of turbidites and protoarc lithologies prior to ~2608 Ma, and metaluminous granitoid plutonism; (iii) 2608–2597 Ma — onset of TR2, collision of Snare protoarc with Central Slave Basement Complex, D2/M2 crustal thickening and mid-crustal granulite-facies metamorphism, sychronous with metaluminous and peraluminous plutonism; and (iv) 2597–2586 Ma — orogenic collapse, D3/M3 mid-crustal uplift, granulite-facies metamorphism, and waning metaluminous and peraluminous plutonism. The distribution of igneous rocks yields an "orogenic stratigraphy" with an older upper crust underlain by a younger synorogenic mid-crust. These data can be used to provide constraints for the interpretation of the Slave – Northern Cordillera Lithospheric Evolution (SNORCLE) Lithoprobe transect.

Sign in / Sign up

Export Citation Format

Share Document