Petrology of Peridotite and Pyroxenite Xenoliths from the Jericho Kimberlite: Implications for the Thermal State of the Mantle beneath the Slave Craton, Northern Canada

Kopylova, Maya G.

doi:10.1093/petrology/40.1.79

Cited by 87 publications

(65 citation statements)

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“…and comparable to averages from Tanzania as well as the Slave and Siberian cratons (Lee and Rudnick, 1999;McKenzie and Canil, 1999;Kopylova et al, 1999;, but much lower than low temperature peridotites from the Kaapvaal .…”

Section: Garnet Fades Peridotitessupporting

confidence: 63%

“…The lherzolites show large porphyroclasts of garnet, CPX, OPX and rare olivine, set in a matrix of smaller euhedral crack-free olivine neoblasts (<2 mm) with straight grain (Boyd, 1989;McKenzie and Canil, 1999;Kopylova et al, 1999 Boyd, 1989;Slave, McKenzie and Canil, 1999;Kopylova et al, 1999;Siberia, Boyd et al, 1997;Tanzania, Lee and Rudnick, 1999 CPX from the lherzolites are chemically zoned for Na2O, MgO,TiO2,FeO and CaO (Fig 6). Unlike garnet form this rock type, the shape of the profile is either concave of convex.…”

Section: Garnet Fades Peridotitesmentioning

confidence: 99%

“…4b), as well as the OPX from the garnet-free peridotites from Tanzania (Lee and Rudnick, 1999 Canil, 1999;Kopylova et al, 1999;Berstein et al, 1998), with a good proportion of the population plotting within the diamond inclusion field of Gurney and Zweistra (1995) Canil, 1999;Kopylova et al, 1999) and the Canadian Arctic (Zhao et. al, 1997), as well as the spinels from garnet-free peridotites from Tanzania (Lee and Rudnick, 1999).…”

Section: Garnet-free Peridotitesmentioning

confidence: 99%

“…The recent discoveries of kimberlites in North America and Greenland have provided information on the nature of the mantle under the Slave, Superior and North Atlantic cratons through the study of their hosts xenoliths. Preliminary results from these studies suggests isotopic (Bizzarro et al, 1999) andcompositional (Berstein et al, 1998;Kopylova et al, 1999;Boyd and Canil, 1997;McKenzie and Canil, 1999;Schmidberger and Francis, 1999) differences between North American, Greenlandic and South African suites, that may potentially reflect different styles of lithosphère growth.…”

Section: Introductionmentioning

confidence: 96%

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Major element and isotope geochemistry (Sr Nd and Hf) of mantle derived peridotites carbonatites and kimberlites from Canada and Greeland insights into mantle dynamics

Bizzarro¹

2003

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Illhérité de la differentiation initiale de la Terre. Notre étude confirme donc qu'une telle hétérogénéité était toujours présente aux environ de 3 Ga, mais plus elusive dans les roches juvéniles d'âge <2.7 Ga. Les nouvelles données isotopiques de l'Hf ici présentées favorisent une source et origine communes pour les carbonatites, kimberlites et certain basaltes océaniques. IV ABSTRACTWe report on the major element composition of a suite of kimberlite-hosted peridotite xenoliths from the northern margin of the western Archean craton of Greenland, as well as the isotopic composition (Nd, Sr and Hf) of carbonatites and kimberlites from eastern Canada and southwestern Greenland.Our results indicate that the lithospheric mantle underneath the Sarfartoq area of southwestern Greenland extends to approximately 225 km, and consists of refractory (olivine Mg # >0.9) harzburgites and lherzolites. Moreover, the Sarfartoq peridotites are not characterized by the OPX enrichment observed in peridotites from the Kaapvaàl craton of South Africa, and show more affinity with peridotites from east Greenland (Wiedemann Fjord), Somerset Island (Canadian arctic) and Tanzania. Detailed analyses of constituent minerals reveal that the lithospheric mantle underneath the Sarfartoq area is compositionally layered as follows: (1) an internally stratified upper layer (70 to 180 km) consisting of coarse, un-deformed, refractory garnet-bearing and garnet-free peridotites and, (2) a lower layer (180 to 225 km) characterized by fertile, CPX-bearing, porphyroclastic garnet lherzolites. The stratification observed in the upper refractory harzburgite layer (70-180 km) is reflected by an increase in fertility (e.g. lower olivine abundance and fosterite content) with depth. The sharp nature of the stratification may indicate a two-step process for the formation of this lithosphère, i.e. multistage growth of the lithospheric root.In Sr values suggests that apatite and carbonate precipitated predominantly under non-equilibrium conditions. The isotopic variations observed within individual hand specimens may therefore reflect larger-(regional) scale open-system processes, possibly involving mixing of carbonatitic melts derived from distinct mantle sources, or from a common isotopically heterogeneous mantle. This analytical technique provides a rapid and effective approach to determine the extent of isotopic heterogeneity within a single sample or individual grains, with analytical precision approaching that obtained by conventional TIMS.High-precision Hf isotopic analyses and U-Pb ages of carbonatites and kimberlites from Greenland and eastern North America, including Earth's oldest known carbonatite (3 Ga), indicate derivation from an enriched mantle source. This previously unidentified mantle reservoir of unradiogenic Hf isotopic composition, preserved in the deep mantle for at least 3 billion years, may account for the mass imbalance in Earth's Hf-Nd budget. Our results show that the Early to mid-Archean terrestrial mantle was isotopically much more...

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Section: Garnet Fades Peridotitessupporting

confidence: 63%

Section: Garnet Fades Peridotitesmentioning

confidence: 99%

Section: Garnet-free Peridotitesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

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Major element and isotope geochemistry (Sr Nd and Hf) of mantle derived peridotites carbonatites and kimberlites from Canada and Greeland insights into mantle dynamics

Bizzarro¹

2003

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“…This indicates the xenoliths have undergone higher degrees of melting at some point in their history (e.g" Menzies, i 990; Boyd, i 989). Xenoliths from other cratons such as Siberia, central East Greenland, central West Greenland, and northern North America all have Mg#s comparable to Kaapvaal, pointing to similar degrees of melting (Boyd et al, i 997;Bernstein et al, i 998;Mitchell, i 977, 1978;Eggler et al, 1987;Larsen, 1982;Kopylova et at., 1998Kopylova et at., , 1999. Richards and Hager, 1984;Hager et at., 1985;Su et at., 1994;Li and Romanowicz, 1996;Grand et al 1997;van der Hilst et at., 1997;LithgowBertelloni and Gurnis, 1997;Lithgow-Bertelloni and Silver, i 998).…”

Section: Vm15-22 Continuedmentioning

confidence: 99%

Subduction dynamics at the middle America trench : new constraints from swath bathymetry, multichannel seismic data, and 10BE

Kelly¹

2003

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The long‐wavelength admittance and effective elastic thickness of the Canadian Shield

Kirby

Swain

2014

JGR Solid Earth

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The strength of the cratonic lithosphere has been controversial. On the one hand, many estimates of effective elastic thickness (T e ) greatly exceed the crustal thickness, but on the other the great majority of cratonic earthquakes occur in the upper crust. This implies that the seismogenic thickness of cratons is much smaller than T e , whereas in the ocean basins they are approximately the same, leading to suspicions about the large T e estimates. One region where such estimates have been questioned is the Canadian Shield, where glacial isostatic adjustment (GIA) and mantle convection are thought to contribute to the long-wavelength undulations of the topography and gravity. To date these have not been included in models used to estimate T e from topography and gravity which conventionally are based only on loading and flexure. Here we devise a theoretical expression for the free-air (gravity/topography) admittance that includes the effects of GIA and convection as well as flexure and use it to estimate T e over the Canadian Shield. We use wavelet transforms for estimating the observed admittances, after showing that multitaper estimates, which have hitherto been popular for T e studies, have poor resolution at the long wavelengths where GIA and convection predominate, compared to wavelets. Our results suggest that T e over most of the shield exceeds 80 km, with a higher-T e core near the southwest shore of Hudson Bay. This means that the lack of mantle earthquakes in this craton is simply due to its high strength compared to the applied stresses.

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Petrology of Peridotite and Pyroxenite Xenoliths from the Jericho Kimberlite: Implications for the Thermal State of the Mantle beneath the Slave Craton, Northern Canada

Cited by 87 publications

References 0 publications

Major element and isotope geochemistry (Sr Nd and Hf) of mantle derived peridotites carbonatites and kimberlites from Canada and Greeland insights into mantle dynamics

Major element and isotope geochemistry (Sr Nd and Hf) of mantle derived peridotites carbonatites and kimberlites from Canada and Greeland insights into mantle dynamics

Subduction dynamics at the middle America trench : new constraints from swath bathymetry, multichannel seismic data, and 10BE

The long‐wavelength admittance and effective elastic thickness of the Canadian Shield

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