scholarly journals Oxidation state of the lithospheric mantle beneath Diavik diamond mines, central Slave craton, NWT, Canada

2019 ◽  
Keyword(s):  
Oxidation State ◽  
Lithospheric Mantle ◽  
Slave Craton

Oxidation state of the lithospheric mantle beneath Diavik diamond mine, central Slave craton, NWT, Canada

2009 ◽  
Vol 159 (5) ◽  
pp. 645-657 ◽  
Author(s):  
Steven Creighton ◽  
Thomas Stachel ◽  
Dave Eichenberg ◽  
Robert W. Luth
Keyword(s):  
Oxidation State ◽  
Lithospheric Mantle ◽  
Slave Craton

Electromagnetic images of the Trans-Hudson orogen: the North American Central Plains anomaly revealed

2005 ◽  
Vol 42 (4) ◽  
pp. 457-478 ◽  
Author(s):  
Alan G Jones ◽  
Juanjo Ledo ◽  
Ian J Ferguson
Keyword(s):  
Electrical Properties ◽  
North American ◽  
Upper Mantle ◽  
Lithospheric Mantle ◽  
Three Dimensional ◽  
Conductivity Anomaly ◽  
Central Plains ◽  
Slave Craton ◽  
The North ◽  
Kimberlite Field

Magnetotelluric studies of the Trans-Hudson orogen over the last two decades, prompted by the discovery of a significant conductivity anomaly beneath the North American Central Plains (NACP), from over 300 sites yield an extensive database for interrogation and enable three-dimensional information to be obtained about the geometry of the orogen from southern North Dakota to northern Saskatchewan. The NACP anomaly is remarkable in its continuity along strike, testimony to along-strike similarity of orogenic processes. Where bedrock is exposed, the anomaly can be associated with sulphides that were metamorphosed during subduction and compression and penetratively emplaced deep within the crust of the internides of the orogen to the boundary of the Hearne margin. A new result from this compilation is the discovery of an anomaly within the upper mantle beginning at depths of ~80–100 km. This lithospheric mantle conductor has electrical properties similar to those for the central Slave craton mantle conductor, which lies directly beneath the major diamond-producing Lac de Gras kimberlite field. While the Saskatchewan mantle conductor does not directly underlie the Fort à la Corne kimberlite, which is associated with the Sask craton, the spatial correspondence is close.

scholarly journals Oxidation State of the Lithospheric Mantle below the Massif Central, France

2014 ◽  
Vol 55 (12) ◽  
pp. 2457-2480 ◽  
Author(s):  
Laura Uenver-Thiele ◽  
Alan B. Woodland ◽  
Hilary Downes ◽  
Rainer Altherr
Keyword(s):  
Oxidation State ◽  
Lithospheric Mantle ◽  
Massif Central

scholarly journals Oxidation State of the Lithospheric Mantle Beneath Komsomolskaya–Magnitnaya Kimberlite Pipe, Upper Muna Field, Siberian Craton

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 740 ◽  
Author(s):  
Anna Dymshits ◽  
Igor Sharygin ◽  
Zhe Liu ◽  
Nester Korolev ◽  
Vladimir Malkovets ◽  
...  
Keyword(s):  
Oxygen Fugacity ◽  
Oxidation State ◽  
Siberian Craton ◽  
Lithospheric Mantle ◽  
Redox State ◽  
Kimberlite Pipe ◽  
Good Explanation ◽  
Redox Conditions ◽  
Lateral Heterogeneity ◽  
Physical Processes

The oxidation state of the mantle plays an important role in many chemical and physical processes, including magma genesis, the speciation of volatiles, metasomatism and the evolution of the Earth’s atmosphere. We report the first data on the redox state of the subcontinental lithospheric mantle (SCLM) beneath the Komsomolskaya–Magnitnaya kimberlite pipe (KM), Upper Muna field, central Siberian craton. The oxygen fugacity of the KM peridotites ranges from −2.6 to 0.3 logarithmic units relative to the fayalite–magnetite–quartz buffer (∆logfO2 (FMQ)) at depths of 120–220 km. The enriched KM peridotites are more oxidized (−1.0–0.3 ∆logfO2 (FMQ)) than the depleted ones (from −1.4 to −2.6 ∆logfO2 (FMQ)). The oxygen fugacity of some enriched samples may reflect equilibrium with carbonate or carbonate-bearing melts at depths >170 km. A comparison of well-studied coeval Udachnaya and KM peridotites revealed similar redox conditions in the SCLM of the Siberian craton beneath these pipes. Nevertheless, Udachnaya peridotites show wider variations in oxygen fugacity (−4.95–0.23 ∆logfO2 (FMQ)). This indicates the presence of more reduced mantle domains in the Udachnaya SCLM. In turn, the established difference in the redox conditions is a good explanation for the lower amounts of resorbed diamonds in the Udachnaya pipe (12%) in comparison with the KM kimberlites (33%). The obtained results advocate a lateral heterogeneity in the oxidation state of the Siberian SCLM.

scholarly journals Oxidation state and metasomatism of the lithospheric mantle beneath the Rae Craton, Canada: strong gradients reflect craton formation and evolution

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alan B. Woodland ◽  
Carolin Gräf ◽  
Theresa Sandner ◽  
Heidi E. Höfer ◽  
Hans-Michael Seitz ◽  
...  
Keyword(s):  
Oxidation State ◽  
Lithospheric Mantle ◽  
Depth Range ◽  
Chemical Gradients ◽  
Vertical Variations ◽  
Formation And Evolution ◽  
Somerset Island ◽  
The Relationship ◽  
Further Development ◽  
Textural Evidence

AbstractWe present the first oxidation state measurements for the subcontinental lithospheric mantle (SCLM) beneath the Rae craton, northern Canada, one of the largest components of the Canadian shield. In combination with major and trace element compositions for garnet and clinopyroxene, we assess the relationship between oxidation state and metasomatic overprinting. The sample suite comprises peridotite xenoliths from the central part (Pelly Bay) and the craton margin (Somerset Island) providing insights into lateral and vertical variations in lithospheric character. Our suite contains spinel, garnet-spinel and garnet peridotites, with most samples originating from 100 to 140 km depth. Within this narrow depth range we observe strong chemical gradients, including variations in oxygen fugacity (ƒO2) of over 4 log units. Both Pelly Bay and Somerset Island peridotites reveal a change in metasomatic type with depth. Observed geochemical systematics and textural evidence support the notion that Rae SCLM developed through amalgamation of different local domains, establishing chemical gradients from the start. These gradients were subsequently modified by migrating melts that drove further development of different types of metasomatic overprinting and variable oxidation at a range of length scales. This oxidation already apparent at ~ 100 km depth could have locally destabilised any pre-existing diamond or graphite.

An overview of the Canadian Cordilleran lithospheric mantleThis article is one of a series of papers published in this Special Issue on the theme Lithoprobe — parameters, processes, and the evolution of a continent.

2010 ◽  
Vol 47 (4) ◽  
pp. 353-368 ◽  
Author(s):  
Don Francis ◽  
William Minarik ◽  
Yuliana Proenza ◽  
Lang Shi
Keyword(s):  
Oxidation State ◽  
Lithospheric Mantle ◽  
Mantle Xenolith ◽  
Geothermal Gradient ◽  
Primitive Mantle ◽  
Canadian Cordillera ◽  
S Wave ◽  
The North ◽  
Melting Event ◽  
North American Craton

Recent alkaline basalts have brought xenoliths of the underlying lithospheric mantle to the surface at more than 20 localities along the strike length of the Canadian Cordillera. The populations of 13 of these xenolith suites display a common mode at 39–40 wt.% MgO and 3.0–3.5.0 wt.% Al2O3, corresponding to a relatively fertile lherzolite whose composition could reflect 8%–10% melting of primitive mantle. The present oxidation state of the Cordillera lithospheric mantle obtained from olivine–spinel equilibria is ∼1 log unit below the fayalite–magnetite–quartz (FMQ) buffer, which is essentially the same as the oxidation state at the time of the melting event that stabilized the Cordilleran lithospheric mantle in the mid-Proterozoic, as constrained by the relative variation of Sc and V. Two xenolith suites near the Yukon – British Columbia border exhibit a second stronger mode, corresponding to relatively refractory spinel harzburgite with significantly higher Mg contents (45–46 wt.% MgO) and lower Al contents (0.5–1.0 wt.% Al2O3). These bi-modal mantle xenolith suites overlie a teleseismic S-wave slowness anomaly in the underlying asthenospheric mantle, and the harzburgites appear to have been produced by a more recent, localized partial melting (∼15%) of the lherzolite lithosphere. The temperatures estimated from clinopyroxene–orthopyroxene equilibria indicate that the lithospheric mantle beneath the Canadian Cordillera is significantly hotter than that beneath the adjacent Archean of the North American craton, with temperatures at the Moho on the order of 800 °C, a minimum geothermal gradient of ∼10 °C/km, and a thickness of <∼65 km.

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