TY - JOUR

T1 - Protracted fluid-metasomatism of the Siberian diamondiferous subcontinental lithospheric mantle as recorded in coated, cloudy and monocrystalline diamonds

AU - Skuzovatov, Sergei Yu

AU - Zedgenizov, Dmitry A.

PY - 2019/6

Y1 - 2019/6

N2 - Five typical coated diamonds (from Udachnaya, Yubileynaya, and Aikhal kimberlite pipes) with untypically low microinclusion abundances and four monocrystalline diamonds (Udachnaya, Mir, Nyurbinskaya pipes) that exhibit thin intermediate microinclusion-bearing zones were examined in details for growth structures, characteristic infrared absorption and photoluminescence, and composition of microinclusions. The internal structures of diamonds of both types imply that fluid inclusions entrapment in diamonds does not necessarily relate to the terminal stage of rapid fibrous growth. Instead, nitrogen aggregation state in some diamonds showed that both fibrous coats and inclusion-bearing layers might experience an annealing during mantle residence long enough to pre-date the ultimate kimberlite eruption, whereas the diamonds with internal inclusion-bearing zones also experienced later protracted history of monocrystalline growth. The presence of chloride-carbonate-silicate fluids/melts in monocrystalline diamonds indicate their generation from media generally similar to that observed in some fibrous diamonds. However, the composition of these metasomatizing fluids is different for the mantle beneath Udachnaya (mostly carbonatitic) and other pipes (Aikhal, Yubileynaya, Mir; variable abundance of silicic high-density fluids). The abundance of silica-rich fluids record either a heterogeneous distribution of eclogites in the subcontinental lithospheric mantle, or the operation of silica-rich slab-derived fluids. The inclusion abundance as well as the type of growth (fibrous or monocrystalline) is considered to be controlled by the volume of fluid fluxes; in this case, fluid consumption leads to decreasing growth rates, diminishing inclusion entrainment and stability of layered octahedrons. The detected minor compositional variations of high-density fluids in these diamonds may be due to local scale thermal perturbation in the host source and/or limited chemical heterogeneity of the parental fluid. The high amount of chlorides in high-density fluids from monocrystalline diamonds provide a new evidence for compositions of fluids/melts acting as primary metasomatic agent in the deep mantle of Siberian craton.

AB - Five typical coated diamonds (from Udachnaya, Yubileynaya, and Aikhal kimberlite pipes) with untypically low microinclusion abundances and four monocrystalline diamonds (Udachnaya, Mir, Nyurbinskaya pipes) that exhibit thin intermediate microinclusion-bearing zones were examined in details for growth structures, characteristic infrared absorption and photoluminescence, and composition of microinclusions. The internal structures of diamonds of both types imply that fluid inclusions entrapment in diamonds does not necessarily relate to the terminal stage of rapid fibrous growth. Instead, nitrogen aggregation state in some diamonds showed that both fibrous coats and inclusion-bearing layers might experience an annealing during mantle residence long enough to pre-date the ultimate kimberlite eruption, whereas the diamonds with internal inclusion-bearing zones also experienced later protracted history of monocrystalline growth. The presence of chloride-carbonate-silicate fluids/melts in monocrystalline diamonds indicate their generation from media generally similar to that observed in some fibrous diamonds. However, the composition of these metasomatizing fluids is different for the mantle beneath Udachnaya (mostly carbonatitic) and other pipes (Aikhal, Yubileynaya, Mir; variable abundance of silicic high-density fluids). The abundance of silica-rich fluids record either a heterogeneous distribution of eclogites in the subcontinental lithospheric mantle, or the operation of silica-rich slab-derived fluids. The inclusion abundance as well as the type of growth (fibrous or monocrystalline) is considered to be controlled by the volume of fluid fluxes; in this case, fluid consumption leads to decreasing growth rates, diminishing inclusion entrainment and stability of layered octahedrons. The detected minor compositional variations of high-density fluids in these diamonds may be due to local scale thermal perturbation in the host source and/or limited chemical heterogeneity of the parental fluid. The high amount of chlorides in high-density fluids from monocrystalline diamonds provide a new evidence for compositions of fluids/melts acting as primary metasomatic agent in the deep mantle of Siberian craton.

KW - Coated diamonds

KW - Diamond

KW - Fluid inclusions

KW - Monocrystalline diamonds

KW - Nitrogen

KW - Siberian craton

KW - CRATON RE-OS

KW - INFRARED-ABSORPTION

KW - COEXISTING FLUID

KW - PERIDOTITIC DIAMONDS

KW - CLINOPYROXENE INCLUSIONS

KW - MINERAL INCLUSIONS

KW - NITROGEN AGGREGATION

KW - SYNTHETIC DIAMOND

KW - FIBROUS DIAMONDS

KW - SULFIDE INCLUSIONS

UR - http://www.scopus.com/inward/record.url?scp=85062948429&partnerID=8YFLogxK

U2 - 10.1007/s00710-019-00656-0

DO - 10.1007/s00710-019-00656-0

M3 - Article

AN - SCOPUS:85062948429

VL - 113

SP - 285

EP - 306

JO - Mineralogy and Petrology

JF - Mineralogy and Petrology

SN - 0930-0708

IS - 3

ER -