The K2CO3–CaCO3–MgCO3 System at 6 GPa: Implications for Diamond Forming Carbonatitic Melts

Arefiev, Anton V.; Shatskiy, Anton; Podborodnikov, Ivan V.; Litasov, Konstantin D.

doi:10.3390/min9090558

Cited by 15 publications

(3 citation statements)

References 85 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Energy-dispersive X-ray spectra were collected using an electron beam rastering method, in which the stage is stationary while the electron beam moves over the surface area, with dimensions 5-500 mm at 20 kV accelerating voltage and 1.5 nA beam current. The live counting time for X-ray spectra was 20 s. The obtained data confirmed the K 2 Ca 3 (CO 3 ) 4 and K 2.00 Ca 2.79 Mg 0.21 (CO 3 ) 4 stoichiometries [for more details on the EDS analysis, see Arefiev et al (2019)].…”

Section: Electron Microscopysupporting

confidence: 64%

Coupling between cation and anion disorder in β-K₂Ca₃(CO₃)₄

Rashchenko,

Ignatov,

Shatskiy

et al. 2024

J Appl Crystallogr

View full text Add to dashboard Cite

Since the development of anionic group theory, the spatial arrangement of anionic groups in optical crystals has been believed to determine their functional, such as nonlinear optical, properties. At the same time, cation substitution, resulting in either the appearance of disordered cation sites in a crystal structure or the emergence of cation-ordered superstructures, has been widely used to control material properties. This work demonstrates the coupling between positional cation disorder and orientational disorder of (CO3)2− anions in the β modification of the recently described K2Ca3(CO3)4 material. In contrast to the α modification [P212121, a = 7.39134 (18), b = 8.8153 (2), c = 16.4803 (4) Å], where the ordered cation sublattice favors the non-centrosymmetric orientationally ordered arrangement of (CO3)2− anionic groups, positional cation disorder in β-K2Ca3(CO3)4 [Pnma, a = 7.5371 (2), b = 16.1777 (5), c = 8.7793 (3) Å] within the cation sublattice of the same topology leads to orientational disorder of (CO3)2− groups and the appearance of an inversion center in the average structure.

show abstract

Section: Electron Microscopysupporting

confidence: 64%

Coupling between cation and anion disorder in β-K₂Ca₃(CO₃)₄

Rashchenko,

Ignatov,

Shatskiy

et al. 2024

J Appl Crystallogr

View full text Add to dashboard Cite

show abstract

“…Carbonates, phlogopite and high-Si mica micro-mineral inclusions were found in association with saline HDFs (Izraeli et al 2004), but mica removal is limited by the low abundance of silica and alumina, and crystallization of K-bearing carbonates is required. This is not impossible (e.g., Shatskiy et al 2016, Arefiev et al 2019), but such phases are rare (Logvinova et al 2019a). Last, HDFs of intermediate compositions between carbonatitic and saline compositions are not common in fibrous diamonds (Figs.…”

Section: Formation Of Saline High-density Fluidsmentioning

confidence: 99%

Fluid Inclusions in Fibrous Diamonds

Weiss

Czas

Navon

2022

Reviews in Mineralogy and Geochemistry

View full text Add to dashboard Cite

Giardini (1974, 1975) reported the composition of gases released by crushing diamonds under vacuum. Gas signals of transparent or light-yellow diamonds were similar to the system blank levels (0.2-2 × 10 −5 cm 3 STP, for an empty crushing chamber at 0 °C and 1 bar). However, the crushing of cubic and translucent diamonds at 200 °C yielded gas volumes that were an order of magnitude larger. The main gases released were H 2 O and CO 2 . Gas released by graphitization of diamonds contained mostly CO with minor H 2 and the quantities were >10 −2 cm 3 STP (Kaiser and Bond 1959;Melton and Giardini 1976), but the H 2 may be attributed to a reaction of water during graphitization (Fesq et al. 1975).Early attempts to determine the nature of the material trapped in the microinclusions by X-ray diffraction and X-ray fluorescence were not conclusive (Lonsdale and Milledge 1965;Seal 1966Seal , 1970Harris 1968). Prinz et al. (1975) found "fluffy, filamentous material" in two diamonds from the Democratic Republic of the Congo (DRC), but did not describe the diamonds. The composition obtained by electron probe microanalysis (EPMA) of this material was SiO 2 67 wt%; TiO 2 2.5 wt%; Al 2 O 3 14-17 wt%; FeO 2-3 wt%; MgO 1 wt%; Na 2 O 0.2-2.5 wt% and K 2 O 8.5-10 wt%. As mentioned below, this composition agrees roughly with that of later studies of microinclusion-bearing fibrous diamonds. Fesq et al. (1975) used instrumental neutron activation analysis (INAA) to investigate the nature of impurities in diamonds. They examined groups of diamonds (~10-20 crystals in each sample) with mineral inclusions as well as diamonds with no visible inclusions. They concluded that in addition to mineral inclusions, the diamonds also carried picritic (high-Mg basaltic) melt associated with an H 2 O + CO 2 rich component or phase that carried incompatible trace elements. The presence of a sulfide-rich phase was inferred from the correlation between Fe, Ni, Cu and Co. These impurities were found in diamonds with and without visible inclusions.INAA of coated diamonds was attempted by Kodochigov and co-workers (according to Orlov 1977) and Glazunov et al. (1967). Bibby (1979) used INAA to determine the traceelement composition of a coated diamond. He found low levels in the core, but the coat carried up to 50 ppm Fe and a few ppm of Na, K, Ba and Ce. Based on the good intercorrelation of K, Na, Ba, and the REE and their poor correlation with Sc, Cr, and Mn, he suggested the presence of carbonate microinclusions.

show abstract

“…These studies will benefit from insights provided by recent experimental studies of phase relationships in carbonate systems at mantle pressures (see review by Shatskiy et al 2015b, for example). The study of systems such as K 2 CO 3 -CaCO 3 -MgCO 3 (Arefiev et al 2019) and Na 2 CO 3 -CaCO 3 -MgCO 3 hold particular promise in this regard.…”

Section: Possible Future Directionsmentioning

confidence: 99%