Raman Spectroscopy of High-Pressure Phases in Shocked L6 Chondrite NWA 5011
- 30 Downloads
Abstract—The paper presents the results of studies of thick shock melt veins in the L6 chondrite NWA 5011. The veins contain a wide variety of high-pressure phases that correspond to contrast values of pressure–temperature parameters on equilibrium phase diagrams. Olivine was transformed to ringwoodite and wadsleyite, orthopyroxene to majorite, akimotoite, and bridgmanite glass, maskelynite is converted to jadeite (+SiO2) and lingunite, apatite to tuite, and chromite to the phase with the calcium ferrite (mCF-FeCr2O4) structure. The peak PT shock parameters for NWA 5011 seem to be the highest among the ones for other shocked chondrites according to the wide occurrence of lingunite and bridgmanite glass and are considerably higher than 25 GPa and 2500 K. Akimotoite crystals in a quenched matrix of the shock melt veins were found for the first time. Probably, they initially crystallized as bridgmanite, since akimotoite is not a liquidus phase in the related systems. Plagioclase–chromite aggregates have been established, which characterize the late stages of the shock process and are formed during successive crystallization from isolated pockets of the impact melt.
Keywords:meteorite chondrite ringwoodite majorite akimotoite bridgmanite shock metamorphism
This work was supported by the Russian Foundation for Basic Research (project no. 17-05-00851). D. D. Badyukov was partially supported by the Presidium of the Russian Academy of Sciences (program no. 28).
- 3.P. M. Bell and E. H. Roseboom, Jr., “Melting relationships of jadeite and albite to 45 kilobars with comments on melting diagrams of binary systems at high pressures,” Min. Soc. Am. Spec. Paper 2, 151–169 (1969).Google Scholar
- 6.M. Chen, J. Shu, and H.-K. Mao, “Xieite, a new mineral of high–pressure FeCr2O4 polymorph,” Chinese Sci. Bull. 53 (21), 3341–3345 (2008).Google Scholar
- 13.T. Ishii, H. Kojitani, S. Tsukamoto, K. Fujino, D. Mori, Y. Inaguma, N. Tsujino, T.Yoshino, D. Yamazaki, Y. Higo, K. Funakoshi, and M. Akaogi, “High–pressure phase transitions in FeCr2O4 and structure analysis of new post-spinel FeCr2O4 and Fe2Cr2O5 phases with meteoritical and petrological implications,” Am. Mineral. 99 (8–9), 1788–1797 (2014).CrossRefGoogle Scholar
- 14.J. Konzett, D. Rhede, and D. J. Frost, “The high PT stability of apatite and Cl partitioning between apatite and hydrous potassic phases in peridotite: an experimental study to 19 GPa with implications for the transport of P, Cl and K in the upper mantle,” Contrib. Mineral. Petrol. 163 (2), 277–296 (2012).CrossRefGoogle Scholar
- 17.K. D. Litasov, D. D. Badyukov, and N. P. Pokhilenko, “Formation parameters of high-pressure minerals in the Dhofar 717 and 864 chondrite meteorites,” Dokl. Earth Sci. 485 (1), 327–330.Google Scholar
- 26.T. G. Sharp and P. S. DeCarli, “Shock effects in meteorites,” Meteorites and the Early Solar System II, Ed. by D. S. Lauretta and H. Y. McSween, Jr., (University of Arisona Press, Tucson, 2006), pp. 653–677.Google Scholar