Formation of iron hydride and iron carbide from hydrocarbon systems at ultra high thermobaric conditions

Abstract

The chemical interaction of hydrocarbon systems and iron-bearing minerals was investigated under extreme thermobaric conditions, corresponding to the Earth upper mantle. As a result of the reaction, the formation of iron carbide and iron hydride was detected. The experiments were carried out in diamond anvils cells with laser heating. Natural petroleum from the Korchaginskoe deposit and a synthetic mixture of paraffin hydrocarbons were used as hydrocarbon systems, and pyroxene-like glass and ferropericlase (57Fe enriched) as iron bearing minerals. The experiments were carried out in the pressure range of 26–95 kbar and temperature range of 1000–1500°C (±100°C). As a result of the experiments, the formation of iron hydride was detected at pressure of 26–69 kbar (corresponds to a depth of 100–200 km), and a mixture of iron carbide and iron hydride at pressure of 75–95 kbar (corresponds to a depth of 210–290 km). The formation of hydrides and iron carbides as a results of the interaction of hydrocarbon systems with iron-bearing minerals may indicate the possible existence of these compounds in the upper mantle.