Oxidation of carbon compounds by silica-derived oxygen within impact-induced vapor plumes

Abstract

Impact-induced vapor plumes produce a variety of chemical species, which may play an important role in the evolution of planetary surface environments. In most previous theoretical studies on chemical reactions within impact-induced vapor plumes, only volatile components are considered. Chemical reactions between silicates and volatile components have been neglected. In particular, silica (SiO 2 ) is important because it is the dominant component of silicates. Reactions between silica and carbon under static and carbon-rich "metallurgic" conditions (C/SiO 2 1) are known to occur to produce CO and SiC. Actual impact vapor plumes, however, cool dynamically and have carbon-poor "meteoritic" composition (C/SiO 2 1). Reactions under such conditions have not been investigated, and final products in such reaction systems are not known well. Although CO and SiO are thermodynamically stable at high temperatures under carbon-poor conditions, C and SiO 2 are stable at low temperatures. Thus, CO may not be able to survive the rapidly cooling process of vapor plumes. In this study, we conduct laser pulse vaporization (LPV) experiments and thermodynamic calculations to examine whether interactions between carbon and silica occur in rapidly cooling vapor plumes with meteoritic chemical compositions. The experimental results indicate that even in rapidly cooling vapor plumes with meteoritic compounds are rather efficiently oxidized by silica-derived oxygen and that substantial amounts of both CO 2 and CO are produced. The calculation results also suggest that those oxidation reactions seen in LPV experiments might occur in planetary-scale vapor plumes regardless of impact velocity as long as silicates vaporize.

Kinetics in thermal evolution of Raman spectra of chondritic organic matter to evaluate thermal history of their parent bodies

“…1966; Ishibashi et al. 2013). Although this reaction favors high temperature, it may not be negligible when the carbon content is low with high abundance of silicates as in the case of chondrites.…”

Shock‐induced silicate vaporization: The role of electrons

“…The redox state is an important parameter for determining the composition and amount of species present in the final gas phase. Because the redox state depends strongly on the degree of vaporization of silicates (silicates contain a large amount of oxygen [ Mukhin et al , 1989; Ishibashi et al , 2006; Fuyuki et al , 2007]), the degree of oxidization in impact‐induced vapor clouds is much higher than previously thought.…”

“…Impact‐induced silicate vapor is widely considered to play an important role in a number of geologic events, including the impact origin of the Moon [ Genda and Abe , 2003; Machida and Abe , 2004; Wada et al , 2006; Pahlevan and Stevenson , 2007; Pahlevan et al , 2011], prebiotic organic synthesis during the heavy bombardment period [e.g., Mukhin et al , 1989; Gerasimov et al , 1998; Ishibashi et al , 2006; Fuyuki et al , 2007], the atmospheric blow‐off of early Earth and Mars [e.g., Ahrens , 1993; Melosh and Vickery , 1989; Vickery and Melosh , 1990; Shuvalov and Artemieva , 2002; Shuvalov , 2009; Hamano and Abe , 2010], and the origin of spherule beds [e.g., Lowe et al , 1989; Melosh and Vickery , 1991; Smit , 1999; Kyte et al , 2003; Johnson and Melosh , 2012]. Emission lines from SiO gas have been spectroscopically detected in observations of the extra solar system [ Lisse et al , 2009].…”

Correlating laser‐generated melts with impact‐generated melts: An integrated thermodynamic‐petrologic approach

“…Pulsed laser irradiation with peak intensities of 10 7 –10 14 W cm –2 and with pulse durations in the nanosecond to millisecond range was used in previous experiments [ Gerasimov et al ., ; Kadono et al ., ; Ohno et al ., ; Ishibashi et al ., ] to investigate impact vaporization of planetary materials and to study the physicochemical properties of the laser‐produced vapor plumes in analogy to impact processes. However, as a consequence of the high irradiation intensities used in these studies, the laser‐generated vapor plumes were thermodynamically comparable to vapor plumes generated in impact scenarios with extremely high impact velocities (50–120 km s –1 ).…”