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Kevin H Mahan - One of the best experts on this subject based on the ideXlab platform.
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rheological evolution of a pseudotachylyte bearing deep crustal shear zone in the western Canadian Shield
Journal of Structural Geology, 2020Co-Authors: Omero F Orlandini, Kevin H MahanAbstract:Abstract Crustal-scale continental strike-slip fault systems are typically thought to be thermally segregated into an upper seismogenic expression and a lower zone of ductile deformation likely extending into the lower crust. The ability of the lower crust to sustain stress is fundamental to understanding the mechanical behavior of the lithosphere, yet significant debate exists regarding the strength of the ductile crust. The Cora Lake shear zone in the western Churchill Province of the Canadian Shield is a 4–7 km wide zone of granulite-to upper amphibolite-facies mylonite which hosts synkinematic pseudotachylyte, suggesting a locally strong lower crust. Kilometer-scale mapping suggests that the shear zone localized at a major lithological and terrane boundary, with the pseudotachylyte network centered within the ca. 1 km-wide more intensely deformed, finer-grained ultramylonitic core. In this contribution, we use optical petrography and electron-backscatter diffraction to describe microstructure across a transect of the Cora Lake shear zone. By combining these observations with grain size piezometry, experimental flow laws, and regional pressure-temperature paths, we conclude that stress amplification from a relatively common type of km-scale lithological heterogeneity and cooling history is the most reasonable explanation for the deep crustal pseudotachylyte.
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the role of heterogeneous strain in the development and preservation of a polymetamorphic record in high p granulites western Canadian Shield
Journal of Metamorphic Geology, 2008Co-Authors: Kevin H Mahan, M Williams, Rebecca M. Flowers, Philippe Goncalves, David HoffmansetkaAbstract:Mafic rocks in the Chipman domain of the Athabasca granulite terrane, western Canadian Shield, provide the first well-documented record of two distinct high-P granulite facies events in the same domain in this region. Textural relations and the results of petrological modelling (NCFMASHT system) of mafic granulites are interpreted in terms of a three-stage tectonometamorphic history. Stage 1 involved development of the assemblage Grt + Cpx + Qtz ± Pl (M1) from a primary Opx-bearing igneous precursor at conditions of 1.3 GPa, 850–900 °C. Field and microstructural observations suggest that M1 developed synchronously with an early S1 gneissic fabric. Stage 2 is characterized by heterogeneous deformation (D2) and synkinematic partial retrogression of the peak assemblage to an amphibole-bearing assemblage (M2). Stage 3 involved a third phase of deformation and a return to granulite facies conditions marked by the prograde breakdown of amphibole (Amph2) to produce matrix garnet (Grt3a) and the coronitic assemblage Cpx3b + Opx3b + Ilm3b + Pl3b (M3b) at 1.0 GPa, 800–900 °C. M1 and M3b are correlated with 2.55 and 1.9 Ga metamorphic generations of zircon, respectively, which were dated in a separate study. Heterogeneous strain played a crucial role in both the development and preservation of these rare examples of multiple granulite facies events within single samples. Without this fortuitous set of circumstances, the apparent reaction history could have incorrectly led to an interpretation involving a single-cycle high-grade event. The detailed P–T–t–D history constructed for these rocks provides the best evidence to date that much of the east Lake Athabasca region experienced long-term lower crustal residence from 2.55 to 1.9 Ga, and thus the region represents a rare window into the reactivation and ultimate stabilization processes of cratonic lithosphere.
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Stabilization and reactivation of cratonic lithosphere from the lower crustal record in the western Canadian Shield
Contributions to Mineralogy and Petrology, 2008Co-Authors: Rebecca M. Flowers, Samuel A Bowring, Michael L Williams, Kevin H Mahan, Ian S. WilliamsAbstract:New U–Pb geochronology for an extensive exposure of high-pressure granulites in the East Lake Athabasca region of the western Canadian Shield is consistent with a history characterized by 2.55 Ga stabilization of cratonic lithosphere, 650 million years of lower crustal residence and cratonic stability, and 1.9 Ga reactivation of the craton during lithospheric attenuation and asthenospheric upwelling. High precision single-grain and fragment zircon data define distinctive discordia arrays between 2.55 and 1.9 Ga. U–Pb ion microprobe spot analyses yield a similar range of U–Pb dates with no obvious correlation between date and cathodoluminescence zonation. We attribute the complex U–Pb zircon systematics to growth of the primary populations during a 2.55 Ga high-pressure granulite facies event (~1.3 GPa, 850°C) recorded by the dominant mineral assemblage of the mafic granulite gneisses, with subsequent zircon recrystallization and minor secondary zircon growth during a second high-pressure granulite facies event (1.0 GPa, ~800°C) at 1.9 Ga. The occurrence of two discrete granulite facies metamorphic events in the lower crust, separated by an interval of 650 million years that included isobaric cooling for at least some of this time, suggests that the rocks resided at lower crustal depths until 1.9 Ga. We infer that this phase of lower crustal residence and little tectonic activity is coincident with an extended period of cratonic stability. Detailed structural and thermochronological datasets indicate that multistage unroofing of the lower crustal rocks occurred in the following 200 million years. Extended lower crustal residence would logically be the history inferred for lower crust in most cratonic regions, but the unusual aspect of the history in the East Lake Athabasca region is the subsequent lithospheric reactivation that initiated transport of the lower crust to the surface. We suggest that a weakened strength profile related to the 1.9 Ga heating left the lithosphere susceptible to far-field tectonic stresses from bounding orogens that drove the lower crustal exhumation. An ultimate return to cratonic stability is responsible for the preservation of this extensive lower crustal exposure since 1.7 Ga.
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Geochronological constraints on the Legs Lake shear zone with implications for regional exhumation of lower continental crust, western Churchill Province, Canadian Shield
Contributions to Mineralogy and Petrology, 2006Co-Authors: Kevin H Mahan, Michael J Jercinovic, Julia A Baldwin, M. L. Williams, R. M. Flowers, Samuel A BowringAbstract:The Legs Lake shear zone marks the southeastern boundary of an extensive region (>20,000 km^2) of high-pressure (0.8–1.5+ GPa) granulite-facies rocks in the western Churchill Province, Canada. The shear zone is one of the largest exhumation-related structures in the Canadian Shield and coincides with the central segment of the ∼2,800 km long Snowbird tectonic zone. The movement history of this shear zone is critical for the development of models for the exhumation history of the high-pressure region. We used electron microprobe U–Th–Pb dating of monazite with supplemental ID-TIMS U–Pb geochronology to place constraints on the timing of shear zone activity. Combining these and other data, we suggest that regional exhumation occurred during at least three distinct phases over an ∼150 million year period. The first phase involved high temperature decompression from ∼1.0 to 0.8–0.7 GPa shortly following 1.9 Ga peak metamorphism, possibly under an extensional regime. The second phase involved rock uplift and decompression of the hanging wall to 0.5–0.4 GPa during east-vergent thrusting across the Legs Lake shear zone at ca. 1.85 Ga. This phase was likely driven by early collision-related convergence in the Trans-Hudson orogen. The final phase of regional exhumation, involving the removal of 15–20 km of overburden from both footwall and hanging wall, likely occurred after ∼1.78 Ga and may have been related to regional extensional faulting.
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multistage exhumation and juxtaposition of lower continental crust in the western Canadian Shield linking high resolution u pb and 40ar 39ar thermochronometry with pressure temperature deformation paths
Tectonics, 2006Co-Authors: Samuel A Bowring, Michael L Williams, Kevin H Mahan, Rebecca M. Flowers, Malcolm S Pringle, K V HodgesAbstract:[1] New U-Pb (titanite, apatite, rutile) and 40Ar/39Ar (hornblende, muscovite, biotite) data are linked with existing pressure-temperature-deformation paths to impose detailed temporal constraints on the juxtaposition and unroofing of domains in an extensive (>20,000 km2) region of exhumed lower crust in the East Lake Athabasca region of the western Canadian Shield. In the ∼200 m.y. between circa 1.9 Ga high-pressure granulite facies metamorphism and circa 1.7 Ga unconformable deposition of Athabasca basin sediments on the exhumed rocks, our analysis reveals at least three distinct phases of unroofing at different rates. Specifically, we distinguish (1) an early phase of extensional unroofing in the Chipman domain at rates of 1.5–2.0 km/m.y. from ∼1.0 GPa to ∼0.8 GPa associated with mafic magmatism and metamorphism, (2) an episode of regional contractional uplift and associated unroofing along the Legs Lake shear zone at circa 1850 Ma from 0.7–0.8 GPa to 0.4–0.5 GPa, and (3) a final period of extensional unroofing at rates of 0.2–0.3 km/m.y. from 0.4 to 0.5 GPa that culminated in transport of current exposures to near-surface conditions. The cooling patterns and retrograde assemblages are consistent with pauses between exhumational phases. The apparent convergence of disparate higher temperature histories in several deep crustal domains at circa 1.89–1.88 Ga implies their juxtaposition at 0.7–0.8 GPa conditions. Regional east directed thrusting of the deep crustal domains as a coherent unit at 1.85 Ga juxtaposed the granulites with middle crustal Hearne domain rocks at 0.4–0.5 GPa conditions. The detailed exhumational history allows correlation with changing regional tectonic regimes associated with the amalgamation of Laurentia. The temporal and spatial heterogeneity of exhumation patterns in the East Lake Athabasca region may be a common feature of the unroofing histories of lower crustal rocks.
Michael L Williams - One of the best experts on this subject based on the ideXlab platform.
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Stabilization and reactivation of cratonic lithosphere from the lower crustal record in the western Canadian Shield
Contributions to Mineralogy and Petrology, 2008Co-Authors: Rebecca M. Flowers, Samuel A Bowring, Michael L Williams, Kevin H Mahan, Ian S. WilliamsAbstract:New U–Pb geochronology for an extensive exposure of high-pressure granulites in the East Lake Athabasca region of the western Canadian Shield is consistent with a history characterized by 2.55 Ga stabilization of cratonic lithosphere, 650 million years of lower crustal residence and cratonic stability, and 1.9 Ga reactivation of the craton during lithospheric attenuation and asthenospheric upwelling. High precision single-grain and fragment zircon data define distinctive discordia arrays between 2.55 and 1.9 Ga. U–Pb ion microprobe spot analyses yield a similar range of U–Pb dates with no obvious correlation between date and cathodoluminescence zonation. We attribute the complex U–Pb zircon systematics to growth of the primary populations during a 2.55 Ga high-pressure granulite facies event (~1.3 GPa, 850°C) recorded by the dominant mineral assemblage of the mafic granulite gneisses, with subsequent zircon recrystallization and minor secondary zircon growth during a second high-pressure granulite facies event (1.0 GPa, ~800°C) at 1.9 Ga. The occurrence of two discrete granulite facies metamorphic events in the lower crust, separated by an interval of 650 million years that included isobaric cooling for at least some of this time, suggests that the rocks resided at lower crustal depths until 1.9 Ga. We infer that this phase of lower crustal residence and little tectonic activity is coincident with an extended period of cratonic stability. Detailed structural and thermochronological datasets indicate that multistage unroofing of the lower crustal rocks occurred in the following 200 million years. Extended lower crustal residence would logically be the history inferred for lower crust in most cratonic regions, but the unusual aspect of the history in the East Lake Athabasca region is the subsequent lithospheric reactivation that initiated transport of the lower crust to the surface. We suggest that a weakened strength profile related to the 1.9 Ga heating left the lithosphere susceptible to far-field tectonic stresses from bounding orogens that drove the lower crustal exhumation. An ultimate return to cratonic stability is responsible for the preservation of this extensive lower crustal exposure since 1.7 Ga.
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multistage exhumation and juxtaposition of lower continental crust in the western Canadian Shield linking high resolution u pb and 40ar 39ar thermochronometry with pressure temperature deformation paths
Tectonics, 2006Co-Authors: Samuel A Bowring, Michael L Williams, Kevin H Mahan, Rebecca M. Flowers, Malcolm S Pringle, K V HodgesAbstract:[1] New U-Pb (titanite, apatite, rutile) and 40Ar/39Ar (hornblende, muscovite, biotite) data are linked with existing pressure-temperature-deformation paths to impose detailed temporal constraints on the juxtaposition and unroofing of domains in an extensive (>20,000 km2) region of exhumed lower crust in the East Lake Athabasca region of the western Canadian Shield. In the ∼200 m.y. between circa 1.9 Ga high-pressure granulite facies metamorphism and circa 1.7 Ga unconformable deposition of Athabasca basin sediments on the exhumed rocks, our analysis reveals at least three distinct phases of unroofing at different rates. Specifically, we distinguish (1) an early phase of extensional unroofing in the Chipman domain at rates of 1.5–2.0 km/m.y. from ∼1.0 GPa to ∼0.8 GPa associated with mafic magmatism and metamorphism, (2) an episode of regional contractional uplift and associated unroofing along the Legs Lake shear zone at circa 1850 Ma from 0.7–0.8 GPa to 0.4–0.5 GPa, and (3) a final period of extensional unroofing at rates of 0.2–0.3 km/m.y. from 0.4 to 0.5 GPa that culminated in transport of current exposures to near-surface conditions. The cooling patterns and retrograde assemblages are consistent with pauses between exhumational phases. The apparent convergence of disparate higher temperature histories in several deep crustal domains at circa 1.89–1.88 Ga implies their juxtaposition at 0.7–0.8 GPa conditions. Regional east directed thrusting of the deep crustal domains as a coherent unit at 1.85 Ga juxtaposed the granulites with middle crustal Hearne domain rocks at 0.4–0.5 GPa conditions. The detailed exhumational history allows correlation with changing regional tectonic regimes associated with the amalgamation of Laurentia. The temporal and spatial heterogeneity of exhumation patterns in the East Lake Athabasca region may be a common feature of the unroofing histories of lower crustal rocks.
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dating metamorphic reactions and fluid flow application to exhumation of high p granulites in a crustal scale shear zone western Canadian Shield
Journal of Metamorphic Geology, 2006Co-Authors: Kevin H Mahan, Michael L Williams, Philippe Goncalves, Michael J JercinovicAbstract:The Legs Lake shear zone is a crustal-scale thrust fault system in the western Canadian Shield that juxtaposes high-pressure (1.0+ GPa) granulite facies rocks against shallow crustal (< 0.5 GPa) amphibolite facies rocks. Hangingwall decompression is characterized by breakdown of the peak assemblage Grt + Sil + Kfs + Pl + Qtz into the assemblage Grt + Crd + Bt ± Sil + Pl + Qtz. Similar felsic granulite occurs throughout the region, but retrograde cordierite is restricted to the immediate hangingwall of the shear zone. Textural observations, petrological analysis using P–T/P–MH2O phase diagram sections, and in situ electron microprobe monazite geochronology suggest that decompression from peak conditions of 1.1 GPa, c. 800 °C involved several distinct stages under first dry and then hydrated conditions. Retrograde re-equilibration occurred at 0.5–0.4 GPa, 550–650 °C. Morphology, X-ray maps, and microprobe dates indicate several distinct monazite generations. Populations 1 and 2 are relatively high yttrium (Y) monazite that grew at 2.55–2.50 Ga and correspond to an early granulite facies event. Population 3 represents episodic growth of low Y monazite between 2.50 and 2.15 Ga whose general significance is still unclear. Population 4 reflects low Y monazite growth at 1.9 Ga, which corresponds to the youngest period of high-pressure metamorphism. Finally, population 5 is restricted to the hydrous retrograded granulite and represents high Y monazite growth at 1.85 Ga that is linked directly to the synkinematic garnet-consuming hydration reaction (KFMASH): Grt + Kfs + H2O = Bt + Sil + Qtz. Two samples yield weighted mean microprobe dates for this population of 1853 ± 15 and 1851 ± 9 Ma, respectively. Subsequent xenotime growth correlates with the reaction: Grt + Sil + Qtz + H2O = Crd. We suggest that the shear zone acted as a channel for fluid produced by dehydration of metasediments in the underthrust domain.
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modest movements spectacular fabrics in an intracontinental deep crustal strike slip fault striding athabasca mylonite zone nw Canadian Shield
Journal of Structural Geology, 1995Co-Authors: Simon Hanmer, Michael L Williams, C KopfAbstract:Geometry and strain partitioning within lower-crustal intraplate strike-slip shear zones can be extremely complex, compared with analogous structural levels of interplate strike-slip shear zones sited at plate margins. Striding-Athabasca mylonite zone, Canadian Shield, is a spectacular ca. 500 km long granulite facies continental intraplate shear zone. The shear zone is composed of Middle Archean granulite facies annealed mylonites (ca. 3.13 Ga) and Late Archean (ca. 2.62-2.60 Ga) granulite facies ribbon mylonite belts, which thread a sinuous course along a chain of crustal-scale ‘lozenges’ cored by relatively stiff rocks of mafic to intermediate composition. To the northeast, the mylonites form a N-S-trending, 5–10 km thick, dextral strike-slip belt. To the southwest, this bifurcates into a pair of conjugate strike-slip shear zones, overlain by a contemporaneous dip-slip shear zone. Striding-Athabasca mylonite zone was kinematically inefficient as a strike-slip fault and cannot have accommodated large wallrock displacements. Nevertheless, spectacular granulite facies ribbon mylonites were formed throughout the shear zone, reflecting the very high temperatures (ca. 850–1000 °C), high recrystallization rate/strain rate ratios, and the transpressive nature of the deformation (Wk < 1), possibly accommodated by significant volume loss by magma migration.
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striding athabasca mylonite zone implications for the archean and early proterozoic tectonics of the western Canadian Shield
Canadian Journal of Earth Sciences, 1995Co-Authors: Simon Hanmer, Michael L Williams, C KopfAbstract:Study of the northern Saskatchewan–District of Mackenzie segment of the Snowbird tectonic zone suggests that fragments of relatively stiff mid-Archean crust, possibly arc related, have controlled the localization, shape, and complex kinematics of the multistage Striding–Athabasca mylonite zone during the Archean, as well as the geometry of the Early Proterozoic rifted margin of the western Churchill continent. By the late Archean, the Striding–Athabasca mylonite zone was located in the interior of the western Churchill continent, well removed from the contemporaneous plate margins. Except for the Alberta segment, the Snowbird tectonic zone was not the site of an Early Proterozoic plate margin. We suggest that the geometry of the Archean–Early Proterozoic boundary in the western Canadian Shield represents a jagged continental margin, composed of a pair of reentrants defined by rifted and transform segments. These segments were inherited from Early Proterozoic breakup and controlled by the Archean structure...
David L. G. Noakes - One of the best experts on this subject based on the ideXlab platform.
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groundwater and the incubation and emergence of brook trout salvelinus fontinalis
Canadian Journal of Fisheries and Aquatic Sciences, 1995Co-Authors: Allen R Curry, David L. G. Noakes, George E MorganAbstract:Groundwater was observed to discharge through brook trout (Salvelinus fontinalis) redds during the November to April incubation period in Canadian Shield waters. Groundwater was important for protecting redds from infiltrating surface water and ice. Physical and chemical characteristics of individual redd environments were similar during the incubation period. Substrate temperature and oxygen levels were reduced in nonredd substrates 100 cm from redds. The stability of discharge, temperature, dissolved oxygen, and specific conductance during incubation was similar between redd and nonredd substrates (≤100 cm away). The quality of redd habitats and embryo survival did not appear to be related to female competition for redd sites or time of spawning. There was evidence of density-dependent control of spawning success and the adaptive nature of alevin emergence behaviour in Canadian Shield waters.
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groundwater and the selection of spawning sites by brook trout salvelinus fontinalis
Canadian Journal of Fisheries and Aquatic Sciences, 1995Co-Authors: Allen R Curry, David L. G. NoakesAbstract:Spawning areas selected by brook trout (Salvelinus fontinalis) displayed variable relationships to discharging groundwater across geologic regions. In Canadian Shield waters, spawning was associate...
Jeremy Hall - One of the best experts on this subject based on the ideXlab platform.
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proterozoic evolution of the northeastern Canadian Shield lithoprobe eastern Canadian Shield onshore offshore transect ecsoot introduction and summary
Canadian Journal of Earth Sciences, 2002Co-Authors: Richard J Wardle, Jeremy HallAbstract:The Lithoprobe Eastern Canadian Shield OnshoreOffshore Transect (ECSOOT) has focused on studies of the processes by which the northeastern Canadian (Laurentian) Shield evolved, firstly by the 1.91.8 Ga coalescence of Archean cratons and then by the addition of juvenile crust from the south in the period 1.90.9 Ga. The transect area is a microcosm of continental accretion and also offers a unique opportunity to link the geological evolution of the Canadian Shield with once-adjacent Greenland.
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geophysical characteristics of the continental crust along the lithoprobe eastern Canadian Shield onshore offshore transect ecsoot a review
Canadian Journal of Earth Sciences, 2002Co-Authors: Keith E Louden, Thomas Funck, Jeremy Hall, Sharon DeemerAbstract:The Eastern Canadian Shield OnshoreOffshore Transect (ECSOOT) of the Lithoprobe program included 1200 km of normal-incidence seismic profiles and seven wide-angle seismic profiles across Archean and Proterozoic rocks of Labrador, northern Quebec, and the surrounding marine areas. Archean crust is 3344 km thick. P-wave velocity increases downwards from 6.0 to 6.9 km/s. There is moderate crustal reflectivity, but the reflection Moho is unclear. Archean crust that stabilized in the Proterozoic is similar except for greater reflectivity and a well-defined Moho. Proterozoic crust has similar or greater thickness, variable lower crustal velocities, and strong crustal reflectivity. Geodynamic processes of Paleoproterozoic growth of the Canadian Shield are similar to those observed in modern collisional orogens. The suturing of the Archean Core Zone and Superior provinces involved whole-crustal shearing (top to west) in the Core Zone, linked to thin-skinned deformation in the New Quebec Orogen. The Torngat Orog...
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proterozoic orogens of the northeastern Canadian Shield new information from the lithoprobe ecsoot crustal reflection seismic survey
Canadian Journal of Earth Sciences, 1995Co-Authors: Charles F Gower, C E Keen, Richard J Wardle, Kevin Coflin, Andrew Craig Kerr, Jeremy Hall, Peter CarrollAbstract:As part of the Eastern Canadian Shield Onshore–Offshore Transect (ECSOOT), Lithoprobe acquired 1250 km of deep seismic reflection data along the coast of Labrador and across Ungava Bay, to image evidence of Proterozoic crustal accretion to the Archean nuclei of the Nain and Superior provinces of the Canadian Shield. The relatively pristine Archean crust of the Nain Province has low reflectivity and generally lacks systematic reflector orientations. Reworking of Archean crust on the margins of the Makkovik Province has little effect on this weak signature. In contrast, the Archean crust in the Eastern Churchill (Rae) Province appears to have been overprinted by a strongly developed, whole-crustal, easterly dipping reflection fabric, interpreted to result from Proterozoic collision of the Nain and Superior provinces in the paired New Quebec and Torngat orogens. Juvenile Proterozoic crust in the Makkovik and Grenville provinces also shows strong whole-crustal dipping reflection fabrics, interpretable as outw...
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proterozoic orogens of the northeastern Canadian Shield new information from the lithoprobe ecsoot crustal reflection seismic survey
Canadian Journal of Earth Sciences, 1995Co-Authors: Jeremy Hall, C E Keen, Richard J Wardle, Charles F Gower, Kevin Coflin, Andrew Craig Kerr, Peter CarrollAbstract:As part of the Eastern Canadian Shield Onshore–Offshore Transect (ECSOOT), Lithoprobe acquired 1250 km of deep seismic reflection data along the coast of Labrador and across Ungava Bay, to image evidence of Proterozoic crustal accretion to the Archean nuclei of the Nain and Superior provinces of the Canadian Shield. The relatively pristine Archean crust of the Nain Province has low reflectivity and generally lacks systematic reflector orientations. Reworking of Archean crust on the margins of the Makkovik Province has little effect on this weak signature. In contrast, the Archean crust in the Eastern Churchill (Rae) Province appears to have been overprinted by a strongly developed, whole-crustal, easterly dipping reflection fabric, interpreted to result from Proterozoic collision of the Nain and Superior provinces in the paired New Quebec and Torngat orogens. Juvenile Proterozoic crust in the Makkovik and Grenville provinces also shows strong whole-crustal dipping reflection fabrics, interpretable as outw...
Allen R Curry - One of the best experts on this subject based on the ideXlab platform.
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groundwater and the incubation and emergence of brook trout salvelinus fontinalis
Canadian Journal of Fisheries and Aquatic Sciences, 1995Co-Authors: Allen R Curry, David L. G. Noakes, George E MorganAbstract:Groundwater was observed to discharge through brook trout (Salvelinus fontinalis) redds during the November to April incubation period in Canadian Shield waters. Groundwater was important for protecting redds from infiltrating surface water and ice. Physical and chemical characteristics of individual redd environments were similar during the incubation period. Substrate temperature and oxygen levels were reduced in nonredd substrates 100 cm from redds. The stability of discharge, temperature, dissolved oxygen, and specific conductance during incubation was similar between redd and nonredd substrates (≤100 cm away). The quality of redd habitats and embryo survival did not appear to be related to female competition for redd sites or time of spawning. There was evidence of density-dependent control of spawning success and the adaptive nature of alevin emergence behaviour in Canadian Shield waters.
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groundwater and the selection of spawning sites by brook trout salvelinus fontinalis
Canadian Journal of Fisheries and Aquatic Sciences, 1995Co-Authors: Allen R Curry, David L. G. NoakesAbstract:Spawning areas selected by brook trout (Salvelinus fontinalis) displayed variable relationships to discharging groundwater across geologic regions. In Canadian Shield waters, spawning was associate...
