scholarly journals Petrochemistry of upper mantle eclogites from the Grizzly, Leslie, Pigeon and Sable kimberlites in the Slave Province, Canada

2019 ◽  
Keyword(s):  
Upper Mantle ◽  
Slave Province

scholarly journals Surface-wave images of western Canada: lithospheric variations across the Cordillera–craton boundary

2018 ◽  
Vol 55 (8) ◽  
pp. 887-896 ◽  
Author(s):  
Taras Zaporozan ◽  
Andrew W. Frederiksen ◽  
Alexey Bryksin ◽  
Fiona Darbyshire
Keyword(s):  
Surface Wave ◽  
Phase Velocity ◽  
Upper Mantle ◽  
High Velocity ◽  
Western Canada ◽  
Low Velocity ◽  
Phase Velocities ◽  
Slave Province ◽  
Upper Mantle Structure ◽  
Tectonically Active

Two-station surface-wave analysis was used to measure Rayleigh-wave phase velocities between 105 station pairs in western Canada, straddling the boundary between the tectonically active Cordillera and the adjacent stable craton. Major variations in phase velocity are seen across the boundary at periods from 15 to 200 s, periods primarily sensitive to upper mantle structure. Tomographic inversion of these phase velocities was used to generate phase velocity maps at these periods, indicating a sharp contrast between low-velocity Cordilleran upper mantle and high-velocity cratonic lithosphere. Depth inversion along selected transects indicates that the Cordillera–craton upper mantle contact varies in dip along the deformation front, with cratonic lithosphere of the Taltson province overthrusting Cordilleran asthenosphere in the northern Cordillera, and Cordilleran asthenosphere overthrusting Wopmay lithosphere further south. Localized high-velocity features at sub-lithospheric depths beneath the Cordillera are interpreted as Farallon slab fragments, with the gap between these features indicating a slab window. A high-velocity feature in the lower lithosphere of the Slave province may be related to Proterozic or Archean subduction.

Lithospheric domains and controls on kimberlite emplacement, Slave Province, Canada: Evidence from elastic thickness and upper mantle composition

2005 ◽  
Vol 6 (10) ◽  
pp. n/a-n/a ◽  
Author(s):  
Yvette H. Poudjom Djomani ◽  
William L. Griffin ◽  
Suzanne Y. O'Reilly ◽  
Buddy J. Doyle
Keyword(s):  
Upper Mantle ◽  
Mantle Composition ◽  
Slave Province

Products of 2.65–2.58 Ga orogenesis in the Slave Province correlated with Slave – Northern Cordillera Lithospheric Evolution (SNORCLE) seismic reflection patterns

2002 ◽  
Vol 39 (8) ◽  
pp. 1189-1200 ◽  
Author(s):  
Arie J van der Velden ◽  
Frederick A Cook
Keyword(s):  
Upper Mantle ◽  
Lower Crust ◽  
Seismic Reflection ◽  
Imaging Techniques ◽  
Shear Zones ◽  
Accretionary Wedge ◽  
The West ◽  
Crust And Upper Mantle ◽  
Slave Province ◽  
Lithospheric Evolution

Reflection patterns along Lithoprobe Slave – Northern Cordillera Lithospheric Evolution (SNORCLE) seismic reflection line 1 in the southwestern Slave Province are interpreted as products of tectonic wedging during late Archean lithospheric convergence. The interpretation is aided by application of new seismic imaging techniques, by correlation of upper crustal reflection patterns to known geology, and by a comparison of lithospheric reflection patterns to similar convergent zones elsewhere. In the Yellowknife area, reflection patterns consist of (1) east-dipping reflections at 12–14 s that project into the upper mantle, (2) a wedge-shaped body in the lower crust with an east-dipping reflection fabric that is truncated on the west by (3) a series of west-dipping reflections that outline thrust-and-fold structures in the upper crust. The similarity of these reflection patterns to those of the Proterozoic Fort Simpson – Hottah collision zone ~300 km to the west provides support for the interpretation that reflection patterns beneath the Slave Province are also products of collisional tectonics. Rocks within the Slave Province preserve evidence of a ~2.65–2.58 Ga pan-Slave orogenic event, in which the >2.9 Ga Central Slave Basement collided with the ~2.7 Ga juvenile eastern Slave Province. Their suture is interpreted to be a west-dipping surface at 4–5 s (12–15 km) beneath Yellowknife and to project to the surface east of the profile. In the lower crust and upper mantle, east-dipping reflections are interpreted to delineate a coeval subduction zone and accretionary wedge. The upper crustal thrust-and-fold structures are likely linked to gold-bearing shear zones at Yellowknife. These results provide tantalizing evidence that processes similar to those of modern convergent zones were operational at 2.65–2.58 Ga.

Geochemistry of the late Archean Banting Group, Yellowknife greenstone belt, Slave Province, Canada: simultaneous melting of the upper mantle and juvenile mafic crust

2002 ◽  
Vol 39 (11) ◽  
pp. 1635-1656 ◽  
Author(s):  
Brian Cousens ◽  
Kathy Facey ◽  
Hendrik Falck
Keyword(s):  
Upper Mantle ◽  
Greenstone Belt ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Heavy Rare Earth Element ◽  
Element Abundances ◽  
Slave Province ◽  
Volcaniclastic Rocks ◽  
Felsic Volcanic ◽  
Felsic Rocks

This study investigates the geochemistry and tectonic setting of the 2.66 Ga Banting Group, the younger sequence of volcanic rocks in the Yellowknife greenstone belt, and its relationship to older tholeiitic volcanic rocks of the 2.72–2.70 Ga Kam Group. The Banting Group includes a much higher proportion of felsic volcanic and volcaniclastic rocks than the Kam Group, but mafic to intermediate volcanic rocks are common. Banting basalts are tholeiitic and are melts of Archean depleted upper mantle, as are basalts of the Kam Group. In contrast, Banting dacites and rhyolites have much lower heavy rare earth element abundances and generally have higher initial 143Nd/144Nd than Kam felsic rocks. The chemistry of the felsic rocks provides a geochemical signature to distinguish rocks of Kam versus Banting age where complex structures have obscured the stratigraphy. Whereas Kam felsic rocks evolved from mafic parents by assimilation – fractional crystallization processes, Banting felsic rocks have compositions similar to Archean tonalite–trondhjemite–dacite suites, as well as modern adakites, and appear to be melts of juvenile, garnet-bearing, hydrated mafic crust, possibly underplated Kam basalts. The nearby 2.66 Ga felsic complex at Clan Lake mimics the geochemical systematics of the Banting Group, and thus Banting-like rocks may reflect a regional crustal melting event at this time.

Water Gas May Not Shift in Deep Earth

2020 ◽  
Author(s):  
Nore Stolte ◽  
Junting Yu ◽  
Zixin Chen ◽  
Dimitri A. Sverjensky ◽  
Ding Pan
Keyword(s):  
Formic Acid ◽  
Upper Mantle ◽  
Free Energy Calculations ◽  
Water Gas Shift ◽  
Ab Initio Molecular Dynamics ◽  
Water Gas Shift Reaction ◽  
Carbon Carrier ◽  
Deep Earth ◽  
Shift Reaction ◽  
Water Gas

The water-gas shift reaction is a key reaction in Fischer-Tropsch-type synthesis, which is widely believed to generate hydrocarbons in the deep carbon cycle, but is little known at extreme pressure-temperature conditions found in Earth’s upper mantle. Here, we performed extensive ab initio molecular dynamics simulations and free energy calculations to study the water-gas shift reaction. We found the direct formation of formic acid out of CO and supercritical water at 10∼13 GPa and 1400 K without any catalyst. Contrary to the common assumption that formic acid or formate is an intermediate product, we found that HCOOH is thermodynamically more stable than the products of the water-gas shift reaction above 3 GPa and at 1000∼1400 K. Our study suggests that the water-gas shift reaction may not happen in Earth’s upper mantle, and formic acid or formate may be an important carbon carrier, participating in many geochemical processes in deep Earth.<br>

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