Melt Inclusions in Chromium Spinel of Kimberlites of the Zapolyarnaya Pipe, Upper Muna Field, Siberian Craton

Potapov, Sergey V.; Sharygin, Igor S.; Константинов, К. М.; Данилов, Б. С.; Shcherbakov, Yu. D.; Letnikov, F. A.

doi:10.1134/s1028334x22050130

Cited by 5 publications

(1 citation statement)

References 18 publications

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“…In both cases, the formation of minerals was associated with the late stages of hydrothermal crystallization from solutions enriched by alkali and fugitive components of the alkali silicate liquids [9,10]. Recently tychite [11] and northupite [12] were described from melt inclusions in olivine from mantle xenoliths of kimberlite pipes from Siberia, Russia.…”

Section: Introductionmentioning

confidence: 99%

The Crystal Structure of Manganotychite, Na6Mn2(CO3)4(SO4), and Structural Relations in the Northupite Group

et al. 2023

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The crystal structure of manganotychite has been refined using the holotype specimen from the Alluaiv Mountain, Lovozero massif, Kola peninsula, Russia. The mineral is cubic, Fd3¯, a = 14.0015(3) Å, V = 2744.88(18) Å3, Z = 8, R1 = 0.020 for 388 independently observed reflections. Manganotychite is isotypic to tychite and ferrotychite. Its crystal structure is based upon a three-dimensional infinite framework formed by condensation of MnO6 octahedra and CO3 groups by sharing common O atoms. The sulfate groups and Na+ cations reside in the cavities of the octahedral-triangular metal-carbonate framework. In terms of symmetry and basic construction of the octahedral-triangular framework, the crystal structure of manganotychite is identical to that of northupite, Na3Mg(CO3)2Cl. The transition northupite → tychite can be described as a result of the multiatomic 2Cl− → (SO4)2− substitution, where both chlorine and sulfate ions are the extra-framework constituents. However, the positions occupied by sulfate groups and chlorine ions correspond to different octahedral cavities within the skeletons of Na atoms. The crystal structure of northupite can be considered as an interpenetration of two frameworks: anionic [Mg(CO3)2]2− octahedral-triangular framework and cationic [ClNa3]2− framework with the antipyrochlore topology. Both manganotychite and northupite structure types can be described as a modification of the crystal structure of diamond (or the dia net) via the following steps: (i) replacement of a vertex of the dia net by an M4 tetrahedron (no symmetry reduction); (ii) attachment of (CO3) triangles to the triangular faces of the M4 tetrahedra (accompanied by the Fd3¯m → Fd3¯ symmetry reduction); (iii) filling voids of the resulting framework by Na+ cations (no symmetry reduction); and (iv) filling voids of the Na skeleton by either sulfate groups (in tychite-type structures) or chlorine atoms (in northupite). As a result, the information-based structural complexity of manganotychite and northupite exceeds that of the dia net.

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Section: Introductionmentioning

confidence: 99%

The Crystal Structure of Manganotychite, Na6Mn2(CO3)4(SO4), and Structural Relations in the Northupite Group

et al. 2023

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Confocal Raman spectroscopic study of melt inclusions from peridotite xenoliths in economic and barren kimberlites from Kaapvaal Craton

Khan,

Fedortchouk,

Feichter

et al. 2024

J Raman Spectroscopy

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Melt inclusions trapped in minerals inside xenoliths from kimberlites can help to examine the composition of kimberlite melt and/or metasomatic processes in the subcratonic lithospheric mantle as well as shed more light on the role of these melts in diamond destruction. In this study, confocal Raman spectroscopy of secondary melt inclusions in olivine from xenoliths in five different Kaapvaal Craton kimberlites was used for testing any compositional differences between melt inclusions from economically productive (Bultfontein and Frank Smit) and uneconomic diamond barren (Matsoku, Thaba Putsoa, and Pipe 200) kimberlite pipes. The xenoliths represent a range of pressures (37–45 kbar) and temperatures (1000–1300°C). The 26 daughter minerals identified within melt inclusions include Ca–Mg (±Na, K, P, Cl)‐bearing carbonates, alkali (±Ca, Ba, Cl, F, H2O, CO2)‐bearing sulfates, phosphates, oxides, silicates, and a rare nitrate. The mineral assemblages in melt inclusions are similar in both economic and barren kimberlite pipes from the interior and the edge of the craton, indicating the similar composition of the entrapped melts in all studied samples. However, the petrographic study revealed different metasomatic processes recorded by xenoliths from barren and economic kimberlites. Metasomatism by a melt enriched in K, Ca, and H2O could be instrumental in diamond destruction and the low diamond grade of the three barren kimberlites from Lesotho. Our study revealed no effect of kimberlite melt composition on diamond preservation in the studied kimberlites: instead, diamond grade is most likely affected by diamond destruction in the mantle source prior to kimberlite emplacement with kimberlite ascent.

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High pressure behavior of incommensurately modulated nyerereite structure

Bogdanov,

Rashchenko,

Gavryushkin

et al. 2024

High Pressure Research

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Melt Inclusions in Chromium Spinel of Kimberlites of the Zapolyarnaya Pipe, Upper Muna Field, Siberian Craton

Cited by 5 publications

References 18 publications

The Crystal Structure of Manganotychite, Na6Mn2(CO3)4(SO4), and Structural Relations in the Northupite Group

The Crystal Structure of Manganotychite, Na6Mn2(CO3)4(SO4), and Structural Relations in the Northupite Group

Confocal Raman spectroscopic study of melt inclusions from peridotite xenoliths in economic and barren kimberlites from Kaapvaal Craton

High pressure behavior of incommensurately modulated nyerereite structure

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