Composition of Hydrocarbons in Diamonds, Garnet, and Olivine from Diamondiferous Peridotites from the Udachnaya Pipe in Yakutia, Russia

Abstract

Volatile components in diamonds, associated garnet (pyrope), and olivine from two extremely rare xenoliths of diamondiferous peridotites recovered from the Udachnaya kimberlite pipe in Yakutia, Russia, were analyzed by gas chromatography–mass spectrometry (GC–MS) using a Focus DSQ II Series Single Quadrupole GC–MS (Thermo Scientific, USA). These xenoliths are pyrope lherzolite and pyrope dunite based upon compositions of coexisting minerals. Unlike the pyrope lherzolite, which contained pyrope with moderate calcium (Ca)-component content (about 15 mol%), the dunite contained subcalcic chromium (Cr)-pyrope with low Ca-component content (less than 10 mol%). All investigated minerals contained dominating hydrocarbons and their derivatives represented by aliphatic (paraffins, olefins), cyclic (naphthenes, arenes), oxygenated (alcohols, ethers), and heterocyclic (dioxanes, furans) hydrocarbons; nitrogenated, chlorinated, and sulfonated compounds; carbon dioxide (CO2); and water (H2O). The relative concentration (rel%) of total hydrocarbon was 79.7 rel% for diamonds, 69.1 rel% for garnet, and 92.6 rel% for olivine, with a general amount of components ranging from 161 to 206. New data on volatiles in diamonds, associated garnet, and olivine suggest the presence of a wide spectrum of hydrocarbons along with nitrogen (N2), CO2, and H2O in some upper mantle areas. Keywords: Diamond, Volatiles, Hydrocarbons, Pyrope, Olivine, Inclusions