A Comparative Trace Element Study of Diamonds From Premier, Finsch and Jagersfontein Mines, South Africa

Fesq, H.W.; Bibby, D.M.; Erasmus, C.S.; Kable, E.J.D.; Sellschop, J.P.F.

doi:10.1016/b978-0-08-018017-5.50056-0

Cited by 17 publications

(13 citation statements)

References 33 publications

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“…The substitution of elements into the diamond structure has long been an area of study because of its effect on the gem qualities, and hence value, of natural diamond and its effect on the physio-chemical properties of diamond. The first quantitative measurements of trace elements in diamonds were published by Fesq et al (1975). More than 60% of elements in the periodic table can be found in diamond but chiefly it is only nitrogen, boron, hydrogen, silicon, and nickel that substitute into the diamond structure (e.g., Field 1992;Gaillou et al 2012) in routinely measurable quantities.…”

Section: Microscale Components In Diamondsmentioning

confidence: 99%

Diamonds and the Geology of Mantle Carbon

Shirey

Cartigny

Frost

et al. 2013

Reviews in Mineralogy and Geochemistry

385

172

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The most recent advances in diamond science are reviewed, covering a variety of specific topics, such as diamond distribution in Earth, diamond composition, mineralogy and textures, diamond formation, isotope geochemistry of diamond, geochemistry, thermobarometry and geochronology of inclusions in diamonds, geology of mantle carbon. The comprehensive, cross-disciplinary nature of this review identifies some of the areas where important unknowns in diamond research can be addressed with future work: (1) the quantitative partitioning of elements and fractionation of isotopes during diamond growth, (2) the co-genetic (or not) relationship of diamond to its host inclusions and the age of diamonds, (3) the recognition and significance of primordial carbon, primary mantle carbon, or subducted carbon in the composition of diamond, (4) the speciation of C in diamond-forming fluids and the processes that control the oxygen fugacity of the mantle, (5) the deepest diamonds, their ultra-high pressure inclusions and the geodynamic processes occurring in convecting the mantle, (6) the experimental simulation of diamond formation from a variety of mantle fluids and melts, and (7) the nanostructural characteristics of diamond as they relate to all aspects of diamond formation

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Section: Microscale Components In Diamondsmentioning

confidence: 99%

Diamonds and the Geology of Mantle Carbon

Shirey

Cartigny

Frost

et al. 2013

Reviews in Mineralogy and Geochemistry

385

172

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“…Some mineral inclusions, e.g., intergrowths of phlogopite with pyroxene (8,12,13) and phlogopite with calcite (14), are unambiguously evidence that K and H 2 O were present in the diamond-forming medium. It is pertinent to note that, as early as 30 years ago, neutron activation analysis of diamonds without visible inclusions, taken from three South African deposits, revealed a mixture of mostly K and of other components, which was interpreted as evidence of the presence of entrapped melt (15). Principally, more recent information has accrued from micro-and nano-inclusions in mantle-derived and metamorphic diamonds.…”

mentioning

confidence: 99%

The role of mantle ultrapotassic fluids in diamond formation

Palyanov

Shatsky

Sobolev

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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Analysis of data on micro-and nano-inclusions in mantle-derived and metamorphic diamonds shows that, to a first approximation, diamond-forming medium can be considered as a specific ultrapotassic, carbonate/chloride/silicate/water fluid. In the present work, the processes and mechanisms of diamond crystallization were experimentally studied at 7.5 GPa, within the temperature range of 1,400 -1,800°C, with different compositions of melts and fluids in the KCl/K 2CO3/H2O/C system. It has been established that, at constant pressure, temperature, and run duration, the mechanisms of diamond nucleation, degree of graphite-to-diamond transformation, and formation of metastable graphite are governed chiefly by the composition of the fluids and melts. The experimental data suggest that the evolution of the composition of deep-seated ultrapotassic fluids/melts is a crucial factor of diamond formation in mantle and ultrahigh-pressure metamorphic processes. high-pressure experimentA n important stage in solving problems of diamond genesis is constructing a clear physical model of diamond formation (1). One of the key parameters to be modeled is the composition of the diamond crystallization medium, with a fluid being largely considered as a crucial agent in diamond formation. It is generally agreed that the mantle media of diamond crystallization were volatile-saturated melts or fluids (1-7). Carbonbearing fluids and carbonates could be sources of carbon, and the medium could have been saturated with it by redox reactions. Recent studies have been aimed at searching and examining fluid and fluid-containing inclusions in genetically different diamonds. Also, experiments have been performed to model the processes of diamond crystallization in the media compositionally corresponding to the inclusions. It is the combination of these two approaches that permits us to gain deeper insight into diamond genesis and to better understand the specific character of processes of deep-seated mineral formation.Studies of mineral inclusions in diamonds have determined the main types of diamondiferous parageneses: ultramaffic, eclogitic (4,8,9), and intermediate websterite (10) and calc-silicate types (11). Some mineral inclusions, e.g., intergrowths of phlogopite with pyroxene (8, 12, 13) and phlogopite with calcite (14), are unambiguously evidence that K and H 2 O were present in the diamond-forming medium. It is pertinent to note that, as early as 30 years ago, neutron activation analysis of diamonds without visible inclusions, taken from three South African deposits, revealed a mixture of mostly K and of other components, which was interpreted as evidence of the presence of entrapped melt (15). Principally, more recent information has accrued from micro-and nano-inclusions in mantle-derived and metamorphic diamonds. Analysis of the composition of the inclusions in fibrous or cloudy mantle diamonds shows that, at the time of entrapment, the inclusion matter was a specific fluid whose composition belongs to one of the three main types: (i) ...

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“…by Bishop ^ ^-) are probably the significant hosts for K and Rb at depths below ~100km, and it is interesting to check whether total extraction of these minerals into magmas would yield K/Rb ratios which match those for mantle-derived volcanic rocks. Unfortunately the lack of understanding of the different origins of high-K and low K peridotite micas provides a complication, as does possible mica-liquid fractionation (Beswick, 1976), Values of K/Rb for bulk kimberlites (~90-220) are lower than our values for high-K peridotitic mica (210-300) and low-K peridotitic mica (330-550), but greater than the values for inclusion-bearing diamonds (20-130, mean ~70; Fesq et al, 1975b). Similarly, the values of K/Ba for kimberlites (8-39;Fesq et al, 1975) lie between those for high-and low-K peridotitic micas (112-292 and 22-51) and for diamonds (1.5-2.5;Fesq , 1975b).…”

contrasting

confidence: 62%

K, Rb and Ba in micas from kimberlite and peridotitic xenoliths

International Kimberlite Conference Extended Abstracts: 1977

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Highly-sensitive electron microprobe analyses were made for Rb and Ba in micas from peridotitic xenoliths in kimberlites, in MARID-suite nodules, in phlogopite megacrysts, and in kimberlite groundmass minerals (Table 1).Special attention was paid to background for Rb ( Fig. 1); the standard was Corning X-glass (0.49 wt.% Rb20, atomic absorption analysis, J. Ito). Fig. 2 summarizes the ranges and mean for K/Rb and K/Ba. Primary micas from peridotite xenoliths were split into two groups.High-K ones have lower Na, lower BaO (340-880) and higher Rb20 (320-440) than low-K ones (BaO 1720-4000, Rb20 160-260).Phlogopites from the MARID-suite (interpreted as cumulates from kimberlite liquid crystallizing at considerable depth; Dawson and Smith, 1977) have higher Rb 0 than both types of peridotite micas, and the same range of BaO as high-K peridotite micas.Aoki (1974) recorded Rb20 analyses for MARID micas twice greater than ours, whereas Allsopp and Barrett (1975) recorded ~400-530 for Wesselton "nodule" micas which fall in our range of 340-800 for MARID micas.The very wide ranges for megacryst micas (interpreted as phenocrysts; Smith and Dawson, 1975) overlap those for MARID micas, and our range of Rb20 encompasses that for Monastery megacrysts (Rb20 683-963; Allsopp and .The groundmass of micaceous kimberlites contains very rare, Fe-rich micas (Type I) interpreted as xenocrysts from an intrusive precursor (carbonatitic?), and abundant Type II micas interpreted as late-stage primary crystals (Smith, Brennesholtz and Dawson, see another Ext. Abstr.).Both have very wide, overlapping ranges of Rb20 and BaO.BaO concentrations tend to be considerably greater than those for the high-K peridotite, MARID and megacryst groups, but similar to those for the low-K peridotite group.Bulk analyses of kimberlite groundmass micas should be determined essentially by Type II micas, and the K/Rb range for Wesselton groundmass mica ) is at the low end (110-160) of the range (112-1040) found by us for micaceous kimberlites from several localities.

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A Comparative Trace Element Study of Diamonds From Premier, Finsch and Jagersfontein Mines, South Africa

Cited by 17 publications

References 33 publications

Diamonds and the Geology of Mantle Carbon

Diamonds and the Geology of Mantle Carbon

The role of mantle ultrapotassic fluids in diamond formation

K, Rb and Ba in micas from kimberlite and peridotitic xenoliths

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