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Of kimberlite and basalt

Ocean-island basalt–like source of kimberlite magmas from ...

Group 1 kimberlites have Sr-Nd isotope compositions similar to bulk earth. These compositions are consistent with a kimberlite source that is either a relatively unfractionated ocean-island basalt (OIB)–like source, or a mixture of depleted mid-oceanic-ridge basalt and enriched mantle components.

Kimberlites, flood basalts and mantle plumes: New insights ...

Aug 01, 2011 · Available literature reveals that there are at least six Phanerozoic and one Mesoproterozoic flood basalt eruption(s) associated with kimberlites and similar rock types (such as lamproites and lamprophyres) on different continents.The available information on the inferred mantle plume associated with them is also shown in Table 1 together with the two geological boundaries that

Continental alkali basalts as mixtures of kimberlite and ...

Furthermore, major element compositions indicate that each leachate may be a mixture of nodule mineral plus kimberlite. It is suggested that the host alkali basalt lava could have formed by the same mixing process, as the lava and enclosed nodule are in approximate Nd isotopic equilibrium, and calculated mineral/melt partition coefficients for ...

(PDF) Ocean-island basalt like source of kimberlite magmas ...

These compositions are consistent with a kimberlite source that is either a relatively unfractionated ocean-island basalt (OIB) like source, or a mixture of depleted mid-oceanic-ridge basalt and ...

Geochemical and oxygen isotope signatures of mantle ...

Jan 01, 2015 · 1. Introduction. Kimberlites, alkali basalts and lamprophyres are important conveyors of gems, especially for diamond and corundum from the asthenosphere and/or lower lithosphere to the upper crust (Giuliani et al., 2014, Shirey et al., 2013).These magmas carry xenoliths of mantle harzburgite, lherzolite and websterite, and in some localities eclogite, but also xenoliths of the lower

Recent Advances in Understanding the Geology of Diamonds ...

The kimberlite eruptions that transport diamonds to the surface also carry samples of lithospheric mantle rocks called xenoliths. From these samples, we know much about the mantle keel beneath the continents, such as the fact that it also contains about 5% of the high-pressure form of basalt known as eclogite. The mantle keel hosts nearly all ...

Kimberlite - Wikipedia

Kimberlite is an igneous rock, which sometimes contains diamonds.It is named after the town of Kimberley in South Africa, where the discovery of an 83.5-carat (16.70 g) diamond called the Star of South Africa in 1869 spawned a diamond rush and the digging of the open-pit mine called the Big Hole.Previously, the term kimberlite has been applied to olivine lamproites as Kimberlite II, however ...

Komatiites, kimberlites, and boninites - Arndt - 2003 ...

Jun 06, 2003 · In kimberlites and meimechites, it results from low-degree melting at great depth; in komatiites from moderate- to high-degree melting, also at great depth; and in boninites from melting of a refractory source at shallow depths. Alkaline ultramafic magmas (kimberlites and meimechites) are comparable in some ways to alkaline basalts.

Kimberlite Volcanism | Annual Review of Earth and ...

Kimberlite magmas are volatile-rich, silica-poor ultrabasic magmas originating as small-degree mantle melts at depths of 150 km or greater. Alteration and entrained xenoliths obscure their original magma chemistry and properties. Kimberlite magmas decrease temperature by a few hundred degrees during ascent. Changes of melt composition can result as a function of assimilation. Stalling of ...

Kimberlite | Properties, Composition and Formation

Kimberlite is an igneous rock that major source of diamonds.Kimberlite is a variety of peridotite.It is rich in mica minerals content and often in form of crystals of phlogopite. Other containt abundant minerals are chrome-diopside, olivine, and chromium- and pyrope-rich garnet.Kimberlite is typically found in pipes – structures with vertical edges that are roughly circular in cross-section.

Ocean-island basalt–like source of kimberlite magmas from ...

Group 1 kimberlites have Sr-Nd isotope compositions similar to bulk earth. These compositions are consistent with a kimberlite source that is either a relatively unfractionated ocean-island basalt (OIB)–like source, or a mixture of depleted mid-oceanic-ridge basalt and enriched mantle components.

Kimberlite | Properties, Composition and Formation

Kimberlite is an igneous rock that major source of diamonds.Kimberlite is a variety of peridotite.It is rich in mica minerals content and often in form of crystals of phlogopite. Other containt abundant minerals are chrome-diopside, olivine, and chromium- and pyrope-rich garnet.Kimberlite is typically found in pipes – structures with vertical edges that are roughly circular in cross-section.

Kimberlites can be found in narrow.docx - Kimberlites can ...

In kimberlite, olivine is large and conspicuous, while lamproite has Ti-phlogopite and lamprophyre has biotite and amphibole. They are all derived from magma types that erupt rapidly from small amounts of melt, are rich in volatiles and magnesium oxide, and are

Recent Advances in Understanding the Geology of Diamonds ...

The kimberlite eruptions that transport diamonds to the surface also carry samples of lithospheric mantle rocks called xenoliths. From these samples, we know much about the mantle keel beneath the continents, such as the fact that it also contains about 5% of the high-pressure form of basalt known as eclogite. The mantle keel hosts nearly all ...

Viscosity of hydrous kimberlite and basaltic melts at high ...

Viscosity of hydrous kimberlite and basaltic melts at high pressures E.S. Persikov a,*, ... of more than 3500 basalt samples from almost all regions of the world (Table 1) was selected as a ...

Ocean-island basalt like source of kimberlite magmas from ...

Group 1 kimberlites have Sr-Nd isotope compositions similar to bulk earth. These compositions are consistent with a kimberlite source that is either a relatively unfractionated ocean-island basalt (OIB) like source, or a mixture of depleted mid-oceanic-ridge basalt and enriched mantle components.

Geology of the KAO Mine, Lesotho - Storm Mountain Diamonds

These kimberlite units and 1 non-kimberlite unit are summarised below in order of volcanic emplacement from youngest to oldest with further details provided in Table 1. 6. Central Basalt Breccia – not economic. Basalt dominated (>90%).

Kimberlite Volcanism | Annual Review of Earth and ...

Kimberlite magmas are volatile-rich, silica-poor ultrabasic magmas originating as small-degree mantle melts at depths of 150 km or greater. Alteration and entrained xenoliths obscure their original magma chemistry and properties. Kimberlite magmas decrease temperature by a few hundred degrees during ascent. Changes of melt composition can result as a function of assimilation. Stalling of ...

Evidence for olivine deformation in kimberlites and other ...

Jan 29, 2020 · This paper highlights published and new field and petrographic observations for late-stage (crustal level) deformation associated with the emplacement of kimberlites and other mantle-derived magmas. Thus, radial and tangential joint sets in the competent 183 Ma Karoo basalt wall rocks to the 5 ha. Lemphane kimberlite blow in northern Lesotho have been ascribed to stresses linked to eruption

Geology of the BK9 kimberlite (Damtshaa, Botswana ...

Jun 15, 2011 · The BK9 kimberlite consists of three overlapping pipes. It contains two dark varieties of massive volcaniclastic kimberlite, informally termed dark volcaniclastic kimberlite (DVK). DVK(ns) is present in the north and south pipes and is interbedded with lenses of basalt breccia at the margins of the pipes. DVK(c) is present within the central pipe where it is overlain by a sequence of basalt ...

Temperature changes in ascending kimberlite magma - NASA/ADS

We present a thermodynamical model of kimberlite magma ascent from 200 km depth and from 400 km depth. We model four different magma compositions, a basalt and a carbonatite to bound kimberlite behaviour and two intermediate cases that represent Kimberlite 1 has properties intermediate to carbonatite and basalt, and kimberlite 2 has properties that are closer to basalt.

Growth of bultfonteinite and hydrogarnet in metasomatized ...

Feb 10, 2010 · Bultfonteinite and hydrogarnet occur within basalt xenoliths, in the southern pipe of the B/K9 kimberlite. The kimberlite forms part of a cluster of over 50 kimberlites of Cretaceous age (ca. 90 Ma) in the Orapa District, and consists of three coalesced pipes (north, central and south), which separate at a depth of 250 m below the surface (Field et al. 1997, 2008; Field and Selfe 1996).

Kimberlite vs Basalt - Compare Nature

1 Definition. 1.1 Definition. Kimberlite is a rare, blue-tinged, coarse-grained intrusive igneous rock, which sometimes contains diamonds and is mostly found in South Africa and Siberia. Basalt is a common extrusive igneous rock formed by the rapid cooling of

Review: Geophysical Methods for Kimberlite, Prospecting ...

Dec 06, 2018 · The unweathered kimberlite at depth gives a positive anomaly, and must be more dense than the average density of basalt. Since the anomalies over quite large pipes in basalt are small (1 or 2 milligal), accurate terrain corrections and allowances for any substantial variations in the thickness of the overburden and for any regional gravity ...

Kimberlite | Properties, Composition and Formation

Kimberlite is an igneous rock that major source of diamonds.Kimberlite is a variety of peridotite.It is rich in mica minerals content and often in form of crystals of phlogopite. Other containt abundant minerals are chrome-diopside, olivine, and chromium- and pyrope-rich garnet.Kimberlite is typically found in pipes – structures with vertical edges that are roughly circular in cross-section.

Peridotite: Igneous Rock - Pictures, Definition & More

Kimberlite with diamond: Kimberlite, the rock that is found in many diamond pipes, is a variety of peridotite. The specimen above is a piece of kimberlite with numerous visible grains of phlogopite and a six millimeter octahedral diamond crystal of about 1.8 carats. This specimen is from the Finsch Diamond Mine in South Africa.

Komatiites, kimberlites, and boninites

kimberlites have higher concentrations of incompatible elements than Group I kimberlites, and their isotopic compositions are those of an old, geochemically enriched source (high 87Sr/86Sr, low 143Nd/144Nd). Group I kimber-lites have the isotopic features of a more depleted source, like a mantle plume or convecting upper mantle [Mitchell, 1986].

Generation of kimberlite magmas: Conditions and mechanisms ...

The transition from a kimberlite to melililite melt is achieved by a reduction in the CO 2 pressure from 8-6 to 4-3 GPa, and with a further decrease in pressure, the melt may become a basalt or ...

(PDF) Geology of the Kroonstad kimberlite cluster, South ...

The Cretaceous (133Ma) Kroonstad Group II Kimberlite Cluster is located approximately 200km south west of Johannesburg on the Kaapvaal Craton. The cluster is made up of six kimberlite pipes and ...

Kimberlites can be found in narrow.docx - Kimberlites can ...

In kimberlite, olivine is large and conspicuous, while lamproite has Ti-phlogopite and lamprophyre has biotite and amphibole. They are all derived from magma types that erupt rapidly from small amounts of melt, are rich in volatiles and magnesium oxide, and are

Kimberlite ascent by assimilation-fuelled buoyancy | Nature

Jan 18, 2012 · Kimberlite magmas have the deepest origin of all terrestrial magmas and are exclusively associated with cratons 1,2,3.During ascent, they travel through about

(PDF) Origin of HIMU and EM-1 domains sampled by ocean ...

by ocean island basalt (OIB), kimberlite and carbonatite magmas are produced entirely by CO 2-fluxed. melting in the lower mantle. The region of formation of the HIMU-EM complementary reservoirs is.

Lherzolite xenoliths in kimberlites and basalts ...

Electron and ion microprobe analyses for P, Si, Ti, Al, Cr, V, Sc, Fe, Mn, Mg, Ni, Co, Ca, Sr, Na, K and Li in olivine, pyroxene and garnet in 42 'cold' (1150oC) garnet lherzolites from kimberlites, 9 spinel lherzolites from kimberlites and 18 from alkali basalts, and one 'cold' garnet lherzolite from the Malaita alnoite, are ...

Emplacement temperatures of pyroclastic and volcaniclastic ...

Jun 15, 2011 · Orapa A/K1 kimberlite pipe, Botswana. The Orapa A/K1 kimberlite (Figs. 1a and 2a) comprises two steep-sided coalescing pipes (north and south) that were intruded at ∼92.1 Ma through Archaean basement (granite-gneisses and tonalites) and Phanerozoic sediments and basalt lavas of the Karoo Supergroup (Field and Scott Smith 1999).The geology of the Orapa A/K1 pipe is described by

Clinopyroxene-corundum assemblages from alkali basalt and ...

Geochemical and oxygen isotope signatures of mantle corundum megacrysts from the Mbuji-Mayi kimberlite, Democratic Republic of Congo, and the Changle alkali basalt, China. Comptes Rendus Geoscience, Vol. 347, Issue. 1, p. 24.