Emplacement and reworking of Cretaceous, diamond-bearing, crater facies kimberlite of central Saskatchewan, Canada

Leckie, Dale A.; Kjarsgaard, B A; Bloch, John; McIntyre, David J.; McNeil, D H; Stasiuk, Lavern D.; Heaman, Larry M.

doi:10.1130/0016-7606(1997)109<1000:earocd>2.3.co;2

Cited by 56 publications

(28 citation statements)

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“…Geological and geochronological data constrain their ages to between 98 and 112 Ma (Leckie et al 1997). The Cretaceous strata intruded by the kimberlites overlie rocks of the Glennie Domain, a reworked Archean microcontinent within the 1.9 Ga Trans Hudson orogen, a collisional belt developed between the Archean Hearne and Superior Provinces (Lewry et al 1994).…”

Section: Fort a La Corne Saskatchewanmentioning

confidence: 99%

Lithospheric roots beneath western Laurentia: the geochemical signal in mantle garnets

et al. 2003

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This study presents major and trace element data for 243 mantle garnet xenocrysts from six kimberlites in parts of western North America. The geochemical data for the garnet xenocrysts are used to infer the composition, thickness, and tectonothermal affinity of the mantle lithosphere beneath western Laurentia at the time of kimberlite eruption. The garnets record temperatures between 800 and 1450°C using Ni-in-garnet thermometry and represent mainly lherzolitic mantle lithosphere sampled over an interval from about 110-260 km depth. Garnets with sinuous rare-earth element patterns, high Sr, and high Sc/V occur mainly at shallow depths and occur almost exclusively in kimberlites interpreted to have sampled Archean mantle lithosphere beneath the Wyoming Province in Laurentia, and are notably absent in garnets from kimberlites erupting through the Proterozoic Yavapai Mazatzal and Trans-Hudson provinces. The similarities in depths of equilibration, but differing geochemical patterns in garnets from the Cross kimberlite (southeastern British Columbia) compared to kimberlites in the Wyoming Province argue for post-Archean replacement and (or) modification of mantle beneath the Archean Hearne Province. Convective removal of mantle lithosphere beneath the Archean Hearne Province in a "tectonic vise" during the Proterozoic terminal collisions that formed Laurentia either did not occur, or was followed by replacement of thick mantle lithosphere that was sampled by kimberlite in the Triassic, and is still observed there seismically today.Résumé : Cette étude présente les données sur les éléments majeurs et les éléments traces pour 243 xénocristaux de grenat de manteau de six kimberlites provenant de régions de l'ouest de l'Amérique du Nord. Les données géochimi-ques des xénocristaux de grenat sont utilisées pour déduire la composition, l'épaisseur et l'affinité tectonothermique de la lithosphère du manteau sous la Laurentia occidentale au moment des éruptions kimberlitiques. Au moyen de la thermométrie du Ni dans le grenat, on découvre que les grenats enregistrent des températures entre 800 et 1450 ºC et représentent surtout la lithosphère du manteau à lherzolite échantillonnée sur un intervalle d'environ 110 à 260 km de profondeur. Les grenats présentant des patrons sinueux d'éléments de terres rares, un Sr élevé, et un rapport Sc/V élevé se trouvent surtout à de faibles profondeurs et se trouvent presque exclusivement dans des kimberlites qui, selon nos interprétations, ont échantillonné le manteau lithosphérique archéen sous la Province de Wyoming dans la Laurentia; ces caractéristiques sont notablement absentes dans les grenats des kimberlites qui ont fait éruption à travers les provinces de Yavapai Mazatzal et Trans-Hudson (Protérozoïque). Les similitudes dans les profondeurs d'équilibre mais des patrons géochimiques différents dans des grenats des kimberlites de Cross (sud-est de la Colombie-Britannique), lorsqu'ils sont comparés aux patrons des kimberlites de la Province de Wyoming, plaident en faveur d'un remplaceme...

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Section: Fort a La Corne Saskatchewanmentioning

confidence: 99%

Lithospheric roots beneath western Laurentia: the geochemical signal in mantle garnets

et al. 2003

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“…Small volcanoes, whether cones, rings or maars, are often called "monogenetic", but many have been revealed by closer study to have had long histories of multiple eruption (Leckie et al, 1997;Freda et al, 2006;Harvey et al, 2009). For this reason we prefer the descriptive and encompassing term "small" for these volcanoes, while recognizing that most will also be the products of a single eruption.…”

Section: Small Volcanoesmentioning

confidence: 99%

“…Lefebvre and Kurszlaukis, 2008;Pittari et al, 2008), and are associated with significant volumes of volcaniclastic kimberlite that is not in a diatreme, and instead comprises remnants of tuff cones or tuff rings. The surficial deposits are intercalated with sedimentary deposits that provide evidence for repeated subaerial to submarine eruption over millions of years (e.g., Leckie et al, 1997;Zonneveld et al, 2004;Kjarsgaard et al, 2006Kjarsgaard et al, , 2009a). …”

Section: Introductionmentioning

confidence: 99%

Maar-diatreme volcanoes: A review

White

Ross

2011

Journal of Volcanology and Geothermal Research

331

251

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Maar-diatreme volcanoes are produced by explosive eruptions that cut deeply into the country rock. A maar is the crater cut into the ground and surrounded by an ejecta ring, while the diatreme structure continues downward and encloses diatreme and root zone deposits. Here we attempt an evenhanded review of maardiatreme volcanology that extends from mafic to kimberlitic varieties, and from historical maar eruptions to deeply eroded or mined diatreme structures. We conclude that maar-diatreme eruptions are episodic. Ejecta rings provide invaluable insight into eruption processes and sequence, but are incomplete records of diatreme formation. Deposits within the diatreme structure include, in varying proportions, lower unbedded deposits sometimes typified by subvertical contacts among domains of debris emplaced sequentially, and upper bedded deposits formed by sedimentation on surfaces open to the atmosphere. A basal root zone comprises the transition from coherent magmatic feeder dike to clastic deposits formed by fragmentation of magma and enclosing country rock; root zones are irregular in form, and the clastic deposits are typically intruded by contorted dikes. Irregular root zone-like chaotic breccias cut by contorted dikes are also present within diatreme deposits, where they represent intra-diatreme fragmentation zones and record changes in the location of the explosion locus during eruption.

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“…Studies of glacial erosion have demonstrated that glaciers moving over regionally fiat terrane, as large tracts of the Kaapvaal craton would have been in PermoCarboniferous times, are unlikely to have cut deeply into bedrock (unlike glaciers in valleys). Hence, in NW Canada, which has undergone a recent glaciation, many kimberlites are preserved high in crater facies with graded lapilli-tuffs (Leckie et al 1997;Carlson et al 1998;Field & Scott-Smith 1998) although some may have had a pre-glacial cover of variable thickness.…”

Section: The Namibian Mega-placermentioning

confidence: 97%

Diamond mega-placers: southern Africa and the Kaapvaal craton in a global context

Bluck

Ward

Wit

2005

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Diamond mega-placers, defined as -> 50 million carats at -95% gem quality, are known only from along the coast of southwestern Africa, fringing the Kaapvaal craton, where two are recognized. One is associated with the Orange-Vaal dispersal, the other, to the south, has an uncertain origin. Placers are residual when left on the craton, transient when being eroded into the exit drainage, and terminal. Terminal placers, the final depositories of diamonds, have the greatest probability of being a mega-placer. There are four main groups of controls leading to the development of a mega-placer" the craton, the drainage, the nature of the environment at the terminus and the timing.Cratons, being buoyant, have a tendency to leak diamonds into surrounding basins; however, being incompressible they may have orogens converge onto them resulting in some lost sediment being returned as foreland basin fills. The craton size, its diamond-fertility and the retention of successive kimberlite intrusions that remain available to the final drainage, are significant to mega-placer development.Maximum potential recovery is achieved when the drainage delivering diamonds to the mega-placer is efficient, not preceded by older major drainages and focuses the supply to a limited area of the terminal placer. There should be sufficient energy in the terminal placer regime to ensure that sediment accompanying the diamonds is removed to areas away from the placer site. All conditions should be near contemporaneous and most were satisfied in the Orange-Vaal Rivers-Kaapvaal system and mega-placers were consequently generated.

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Emplacement and reworking of Cretaceous, diamond-bearing, crater facies kimberlite of central Saskatchewan, Canada

Cited by 56 publications

References 0 publications

Lithospheric roots beneath western Laurentia: the geochemical signal in mantle garnets

Lithospheric roots beneath western Laurentia: the geochemical signal in mantle garnets

Maar-diatreme volcanoes: A review

Diamond mega-placers: southern Africa and the Kaapvaal craton in a global context

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