..., together with associated dykes, is precursor to the main Wesselton pipe and contains: aphanitic kimberlite with a carbonatitic groundmass of calcite, perovskite, spinel, serpentine and phlogopite, with variations from rocks rich in olivine microphenocrysts to rocks with little or no olivine; macrocrystic...

... contents. The solvents used were a natural kimberlite from Wesselton Mine, South Africa and a synthetic H 2 O-free and CO 2 -rich kimberlite. Experiments with the Wesselton kimberlite were carried out at 1400 and 1500 °C under 1.0 GPa and those with the synthetic kimberlite were conducted at 1500 °C under...

...Andrew J. Berry; Gregory M. Yaxley; Brendan J. Hanger; Alan B. Woodland; Martin D. de Jonge; Daryl L. Howard; David Paterson; Vadim S. Kamenetsky Abstract The oxidation state of Fe in garnets in a garnet peridotite xenolith from the Wesselton kimberlite (South Africa) was quantitatively mapped...

... garnets in equilibrium with orthopyroxene and/or clinopyroxene, after Sobolev et al. (1973) and Grütter et al. (2004). The compositions are shown for garnets exsolved in orthopyroxene megacrysts and orthopyroxenes found in mantle peridotites entrained by various kimberlite pipes from the Kaapvaal...

... samples from Koidu, Sierra Leone ( Taylor et al . 1994 ). F ig . 3. Primitive-mantle-normalized spectra of samples from Wesselton Floors Sills kimberlites, South Africa ( le Roex et al . 2003 ). Macrocrystic samples are represented by circles, aphanitic samples by squares. Samples identified...

... that diamondiferous kimberlites have sampled both garnet and chromite from the harzburgitic layer, but low-grade pipes have sampled only chromite. Diamond formation probably is due to the oxidation of methane-rich, silica-bearing fluids: Fe 2 O 3 (in chromite) + CH 4 → C + H 2 O + FeO (in chromite), accompanied...

... began to crystallize [ 2 ]. Small differences in the initial composition of the magmas have been magnified by extreme fractional crystallization, to produce distinctive ilmenite suites. Some nearby pipes, such as Kimberley-Wesselton-Olifantsfontein, appear to have sampled identical highly fractionated...

... also assigned to the Goedgenoeg Formation, which underlies the Makwassie Formation in Wesselton Mine at Kimberley, gave an age of 2781 ± 5 Ma. A 30 Ma period of Goedgenoeg volcanism is considered to be unlikely. The older sample may rather be a time-correlate of a stratigraphically lower unit...

... or ditrigonal dissolution layers, and drop-shape hillocks. The obtained resorption rates at these P-T- f O 2 parameters indicate that the absence of diamond in kimberlites or low-grade potentially diamondiferous kimberlite pipes might be caused by oxidizing metasomatic events in the lithospheric mantle...

... agents used include an aphanitic kimberlite from Wesselton Mine, South Africa, and a lamproite from Mount North, West Kimberley, Australia. With increasing run duration, diamond morphology changed from a sharp octahedron through combinations of octahedron and tetrahexahedroidal forms to spherical...

...S.I. Kostrovitsky; D.A. Yakovlev; L.F. Suvorova; E.I. Demonterova Abstract ––A dike of rock similar in composition to carbonatites has been found in the Aikhal diamondiferous pipe of the Alakit–Markha field of the Yakutian kimberlite province (YaKP). The fine-grained rock of essentially carbonate...

.... ( 1986 ) The petrogenesis of the Wesselton mine kimberlites, Kimberley, South Africa. University of Cape Town, Cape Town. Skinner, E.M.W., and Marsh, J.S ( 2004 ) Distinct kimberlite pipe classes with contrasting eruption processes. Lithos , 76 , 183 –200. Sonin, V.M., Zhimulev, Y.I...

... 3 2− ions and that the solubility of CO 2 in the melt would control the amount of resorption. Their experiments, however, were performed in natural Wesselton kimberlite ( Edgar et al. , 1988 ) with a complex composition, which does not allow the individual effects of different components...

... ). The compositions of primary kimberlite magma have been a subject of discussions since the discovery of first kimberlite pipes ( Becker and le Roex, 2006 ; Brey et al., 2008 , 2009 , 2011 ; Dasgupta et al., 2013 ; Dawson, 1980 ; Foley, 2011 ; Girnis and Ryabchikov, 2005 ; Girnis et al., 1995 , 2011...

...Lawrence A. Taylor; Mahesh Anand; Prinya Promprated; Christine Floss; Nikolai V. Sobolev Abstract Large diamonds (10–200 carats) from Udachnaya, Mir, and Aikhal kimberlite pipes of Yakutia contain variable mineral inclusions typical of diamonds of smaller size. Among these inclusions, extracted...

... . [5] S. E. Haggerty , The chemistry and genesis of opaque minerals in kimberlite , Phys. Chem. Earth , vol. 9 , p. 295 , 1975 . [6] J. D. Pasteris , Opaque oxide phases of the De Beers pipe kimberlite (Kimberley, South Africa) and their petrologic significance, Thesis , Yale...

... kimberlite pipe, Diavik, Northwest Territories: (1) 0.03–10.0 mm in diameter size range; (2) 46.7–51.2% modal crystal content; (3) modal% dominance by crystals >1 mm; (4) frequency dominance by crystals <1 mm; and (5) equant-axial crystal shapes that cannot be easily described by a single external...

... by the strong enrichment of garnets with Zr and Ca and the minor increase in Y contents ( Griffin et al., 1999 ). Phlogopite metasomatism is a low-temperature (<1100 °C) type of mantle metasomatism, as shown by the example of peridotites from the Wesselton kimberlite pipe, South Africa ( Griffin et al., 1999...