Topic
Kimberlite
About: Kimberlite is a research topic. Over the lifetime, 3082 publications have been published within this topic receiving 91408 citations.
Papers published on a yearly basis
1 / 2
Papers
TL;DR: The oxygen isotope ratios of phanerozoic zircons from kimberlite pipes in the Kaapvaal Craton of southern Africa and the Siberian Platform vary from 4.7 to 5.9 as mentioned in this paper.
Abstract: The oxygen isotope ratios of Phanerozoic zircons from kimberlite pipes in the Kaapvaal Craton of southern Africa and the Siberian Platform vary from 4.7 to 5.9& VSMOW. High precision, accurate analyses by laser reveal subtle pipe-to-pipe diAerences not previously suspected. These zircons have distinctive chemical and physical characteristics identifying them as mantle-de- rived megacrysts similar to zircons found associated with diamond, coesite, MARID xenoliths, Cr-diopside, K-richterite, or Mg-rich ilmenite. Several lines of evi- dence indicate that these d 18 O values are unaltered by kimberlite magmas during eruption and represent com- positions preserved since crystallization in the mantle, including: U/Pb age, large crystal size, and the slow rate of oxygen exchange in non-metamict zircon. The aver- age d 18 O of mantle zircons is 5.3&,0:1& higher and in equilibrium with values for olivine in peridotite xenoliths and oceanic basalts. Zircon megacrysts from within 250 km of Kimberley, South Africa have average d 18 Oa 5:32 0:17&Ona 28U. Small, but significant, diAerences among other kimberlite pipes or groups of pipes may indicate isotopically distinct reservoirs in the sub-continental lithosphere or asthenosphere, some of which are anomalous with respect to normal mantle values of 5:3 0:3&. Precambrian zircons (2.1-2.7 Ga) from Jwaneng, Botswana have the lowest values yet measured in a mantle zircon, d 18 Oa 3:4 to 4.7&. These zircon megacrysts originally crystallized in mafic or ul- tramafic rocks either through melting and metasomat- ism associated with kimberlite magmatism or during metamorphism. The low d 18 O zircons are best explained by subduction of late Archean ocean crust that ex- changed with heated seawater prior to underplating as eclogite and to associated metasomatism of the mantle wedge. Smaller diAerences among other pipes and dis- tricts may result from variable temperatures of equili- bration, mafic versus ultramafic hosts, or variable un- derplating. The narrow range in zircon compositions found in most pipes suggests magmatic homogenization. If this is correct, these zircons document the existence of sig- nificant quantities of magma in the sub-continental mantle that was regionally variable in d 18 O and this information restricts theories about the nature of ancient subduction.
886 citations
TL;DR: In this article, the authors reported the occurrence of diamonds in situ in crustal rocks: highly retrograded high-pressure metamorphic garnet-pyroxene and pyroxene-carbonate-garnet rocks, biotite gneisses and schists from the Kokchetav massif, northern Kazakhstan, USSR.
Abstract: DIAMONDS commonly occur in kimberlites, lamproites and alluvial sediments derived from these rocks. More recently, diamonds (or their graphite pseudomorphs) have been discovered in ultramafic massifs1 and picrites2. Here we report the occurrence of diamonds in situ in crustal rocks: highly retrograded high-pressure metamorphic garnet–pyroxene and pyroxene–carbonate–garnet rocks, biotite gneisses and schists from the Kokchetav massif, northern Kazakhstan, USSR. The diamonds are cubo-octahedral, averaging 12 μm in size, and occur in zircons, and with euhedral graphite as inclusions in unzoned garnets. We believe that the zircon and garnet matrices protected these diamonds from retrogressive transformation to graphite. Mica, rutile, titanite, clinopyroxene, kyanite and zircon also occur as inclusions in garnet, often intergrown with the diamonds. Equilibration relations of inclusions and host garnets indicate that both diamonds and graphite crystallized from a fluid phase under static conditions at pressures of ⩾40 kbar and temperatures >900–1,000 °C.
837 citations
Book•
30 Apr 1986
TL;DR: In this article, the formation and evolution of Kimberlite Magmatism and Genetic Classifications are discussed, as well as the properties of the Kimberlite fields and Provinces: their Tectonic Setting.
Abstract: 1. Historical Aspects of Kimberlite Petrology.- 2. Kimberlite and Related Rocks.- 3. Kimberlite Magmatism and Textural Genetic Classifications of Kimberlite.- 4. Diatremes and Root Zones.- 5. Kimberlite Fields and Provinces: Their Tectonic Setting.- 6. Mineralogy of Kimberlites.- 7. Geochemistry of Kimberlites.- 8. Experimental Studies Relevant to the Formation and Crystallization of Kimberlite Magma.- 9. Petrogenesis and Evolution of Kimberlite Magma.- Postscript.- References.
784 citations
TL;DR: Isotope analyses of Os, Sr, Nd, and Pb elements were caried out on twelve peridotite xenoliths from the Jagersfontein, Letseng-la-terae, Thaba Patsoa, Mothae, and Premier kimberlites of southern Africa, to investigate the timing and the nature of melt extraction from the continental lithosphere and its relation to the continent formation and stabilization.
725 citations
TL;DR: Sub-calcic garnets encapsulated by diamonds from relatively young (90 Myr) kimberlites in southern Africa, yield ancient Sm-Nd and Rb-Sr model ages (3,200-3,300 Myr) as mentioned in this paper.
Abstract: Sub-calcic garnets encapsulated by diamonds from relatively young (90 Myr) kimberlites in southern Africa, yield ancient Sm–Nd and Rb–Sr model ages (3,200–3,300 Myr). The chemistry and distribution of these and associated sub-calcic garnets from kimberlite concentrate, indicate diamonds formed following enrichment of residual sub-cratonic mantle such as that remaining after widespread extraction of 3,500-Myr komatiitic lavas.
648 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2025 | 64 |
| 2024 | 166 |
| 2023 | 128 |
| 2022 | 258 |
| 2021 | 116 |
| 2020 | 86 |