TY - JOUR

T1 - EFFECT OF C–O–H–N–S FLUIDS ON DIAMOND CRYSTALLIZATION UNDER REDUCING MANTLE CONDITIONS

T2 - (review of experimental data)

AU - Palyanov, Yu.N.

AU - Borzdov, Yu.M.

AU - Kupriyanov, I.N.

AU - Khokhryakov, A.F.

AU - Bataleva, Yu.V.

N1 - Palyanov Yu.N., Borzdov Yu.M., Kupriyanov I.N., Khokhryakov A.F., Bataleva Yu.V. (2026). Effect of C–O–H–N–S fluids on diamond crystallization under reducing mantle conditions (review of experimental data) // Russian Geology and Geophysics, v. 67, No. 7, p. 893–914, DOI: 10.2113/RGG20254970. – EDN WZZPBF. Work is done on state assignment of IGM SB RAS (FWZN-2026-0013) (sections on the effect of nitrogen and water on diamond crystallization), and was supported by the Russian Science Foundation, project No. 24-17-00032 (https://rscf.ru/project/24-17-00032/) (sections on the effect of oxygen, sulfur, and methane–hydrogen fluid on diamond crystallization).

PY - 2026/1

Y1 - 2026/1

N2 - Natural diamonds are polygenic and form over a very wide range of P–T parameters, crystallization medium compositions, and oxygen fugacity. As has been demonstrated in recent years, the genesis of some diamonds is directly related to their crystallization from metal–carbon melts. Since natural mineral formation is assumed to include various components typical of the mantle media, we consider it relevant to analyze the experimental results of the effect of C–O–H–N–S fluids on the crystallization features and indicator properties of diamond. The experimental data presented in this review show that increasing the concentration of fluid components (N, O, S, H2O, CH4–H2) at constant P–T parameters inhibits diamond crystallization in metal–carbon melts and eventually leads to the formation of metastable graphite instead of diamond. Increasing P and T decreases the inhibitory effect of impurities and expands the diamond crystallization region. We have revealed the basic patterns of specific changes in the morphology, defect–impurity composition, and internal structure of diamond crystals, depending on the type and concentration of impurity in the crystallization medium. We have established that impurity-induced specific changes in diamond morphology and trends in nitrogen concentration in diamond are indicative of crystallization conditions and provide a basis for reconstructing diamond formation under reducing conditions in the metal-bearing mantle.

AB - Natural diamonds are polygenic and form over a very wide range of P–T parameters, crystallization medium compositions, and oxygen fugacity. As has been demonstrated in recent years, the genesis of some diamonds is directly related to their crystallization from metal–carbon melts. Since natural mineral formation is assumed to include various components typical of the mantle media, we consider it relevant to analyze the experimental results of the effect of C–O–H–N–S fluids on the crystallization features and indicator properties of diamond. The experimental data presented in this review show that increasing the concentration of fluid components (N, O, S, H2O, CH4–H2) at constant P–T parameters inhibits diamond crystallization in metal–carbon melts and eventually leads to the formation of metastable graphite instead of diamond. Increasing P and T decreases the inhibitory effect of impurities and expands the diamond crystallization region. We have revealed the basic patterns of specific changes in the morphology, defect–impurity composition, and internal structure of diamond crystals, depending on the type and concentration of impurity in the crystallization medium. We have established that impurity-induced specific changes in diamond morphology and trends in nitrogen concentration in diamond are indicative of crystallization conditions and provide a basis for reconstructing diamond formation under reducing conditions in the metal-bearing mantle.

KW - Алмаз

KW - эксперимент

KW - высокие давления

KW - металл-углеродные расплавы

KW - мантия

KW - флюиды

KW - генезис алмаза

KW - Diamond

KW - experiment

KW - high pressures

KW - metal–carbon melts

KW - mantle

KW - fluids

KW - diamond genesis

UR - https://www.mendeley.com/catalogue/5aa2b259-c47c-387b-af6c-95e51185718c/

UR - https://www.scopus.com/pages/publications/105046567862

UR - https://elibrary.ru/item.asp?id=90799794

U2 - 10.2113/rgg20254970

DO - 10.2113/rgg20254970

M3 - Article

VL - 67

SP - 893

EP - 914

JO - Russian Geology and Geophysics

JF - Russian Geology and Geophysics

SN - 1068-7971

IS - 7

ER -