TY - JOUR

T1 - Crystallographic orientation and geochemical features of mineral inclusions in diamonds

AU - Sobolev, N. V.

AU - Seryotkin, Yu V.

AU - Logvinova, A. M.

AU - Pavlushin, A. D.

AU - Ugap'eva, S. S.

PY - 2020/5/1

Y1 - 2020/5/1

N2 - The orientation of 76 mineral inclusions represented by olivine (25 inclusions), pyrope (13 inclusions), and magnesiochromite (38 inclusions) was measured in 16 diamond samples from the major primary diamond deposits of Yakutia: Mir, Udachnaya, Internatsionalnaya, Aikhal, and Yubileynaya kimberlite pipes. The novelty of the study is that it provides a special purposeful approach to selection of samples containing not only olivine inclusions that have been extensively studied in the most recent years after the publication of the book Carbon in Earth (2013). The present collection accounts for more than 25% of all samples studied across the world and includes the most typical mineral inclusions of the predominant peridotitic paragenesis in almost all known kimberlites. Both this experiment and similar studies conducted by foreign colleagues in 2014-2019 have found no inclusions whose orientation meets the epitaxial criterion. Only single magnesiochromite inclusions in three diamonds demonstrate an orientation close to the regular one. A significant correlation between the carbon isotope composition and the mineral composition of inclusions of peridotitic and eclogitic paragenesis diamonds as well as the lack of a correlation with other properties may be considered one of the geochemical features. However, given the numerous published and proprietary data demonstrating the complex diamond growth history and, in some cases, wide variations in the composition of mineral inclusions in different zones, along with the difference in their morphology, the authors a believe that syngenetic and protogenetic inclusions can coexist in the same diamond. This is also confirmed by the discoveries of diamondiferous peridotite and eclogite xenoliths in kimberlites where diamonds are completely enclosed in garnet or olivine. Of particular note is the constant presence of heavy hydrocarbons (rel.%), from pentane (C5H12) to hexadecane (C16H34), that are predominant in fluid inclusions in kimberlite and placer diamonds as well as in pyrope and olivine of diamondiferous peridotite xenoliths.

AB - The orientation of 76 mineral inclusions represented by olivine (25 inclusions), pyrope (13 inclusions), and magnesiochromite (38 inclusions) was measured in 16 diamond samples from the major primary diamond deposits of Yakutia: Mir, Udachnaya, Internatsionalnaya, Aikhal, and Yubileynaya kimberlite pipes. The novelty of the study is that it provides a special purposeful approach to selection of samples containing not only olivine inclusions that have been extensively studied in the most recent years after the publication of the book Carbon in Earth (2013). The present collection accounts for more than 25% of all samples studied across the world and includes the most typical mineral inclusions of the predominant peridotitic paragenesis in almost all known kimberlites. Both this experiment and similar studies conducted by foreign colleagues in 2014-2019 have found no inclusions whose orientation meets the epitaxial criterion. Only single magnesiochromite inclusions in three diamonds demonstrate an orientation close to the regular one. A significant correlation between the carbon isotope composition and the mineral composition of inclusions of peridotitic and eclogitic paragenesis diamonds as well as the lack of a correlation with other properties may be considered one of the geochemical features. However, given the numerous published and proprietary data demonstrating the complex diamond growth history and, in some cases, wide variations in the composition of mineral inclusions in different zones, along with the difference in their morphology, the authors a believe that syngenetic and protogenetic inclusions can coexist in the same diamond. This is also confirmed by the discoveries of diamondiferous peridotite and eclogite xenoliths in kimberlites where diamonds are completely enclosed in garnet or olivine. Of particular note is the constant presence of heavy hydrocarbons (rel.%), from pentane (C5H12) to hexadecane (C16H34), that are predominant in fluid inclusions in kimberlite and placer diamonds as well as in pyrope and olivine of diamondiferous peridotite xenoliths.

KW - Chromite

KW - Coesite

KW - Diamond

KW - Eclogite

KW - Garnet

KW - Geothermobarometry

KW - High and ultrahigh pressures

KW - High-density fluid inclusions

KW - Inclusion morphology

KW - Mineral equilibria

KW - Olivine

KW - Paragenesis

KW - Peridotite

KW - Relative orientation of diamond and inclusions

KW - eclogite

KW - UDACHNAYA KIMBERLITE PIPE

KW - SIBERIAN DIAMONDS

KW - garnet

KW - olivine

KW - peridotite

KW - high-density fluid inclusions

KW - chromite

KW - mineral equilibria

KW - LITHOSPHERIC MANTLE

KW - high and ultrahigh pressures

KW - MIR KIMBERLITE

KW - ECLOGITE XENOLITHS

KW - FLUID INCLUSIONS

KW - relative orientation of diamond and inclusions

KW - paragenesis

KW - inclusion morphology

KW - diamond

KW - TRACE-ELEMENTS

KW - geothermobarometry

KW - coesite

KW - OLIVINE INCLUSIONS

KW - CARBON-ISOTOPE

KW - ISOTOPIC COMPOSITION

UR - http://www.scopus.com/inward/record.url?scp=85089032359&partnerID=8YFLogxK

U2 - 10.15372/RGG2020144

DO - 10.15372/RGG2020144

M3 - Article

AN - SCOPUS:85089032359

VL - 61

SP - 634

EP - 649

JO - Russian Geology and Geophysics

JF - Russian Geology and Geophysics

SN - 1068-7971

IS - 5-6

ER -