Structure of carbonate melts at high pressure

Wednesday, 16 December 2015
Poster Hall (Moscone South)
Jessica Hudspeth1, Chrystele Sanloup1, Charlotte de Grouchy2, Benjamin Cochain1, Konstantin Glazyrin3, Zuzana Konopkova3, Hanns-Peter Liermann4 and Veronika Afonina2, (1)University Pierre and Marie Curie Paris VI, Paris, France, (2)University of Edinburgh, Edinburgh, United Kingdom, (3)DESY Deutsches Elektronen Synchrotron, Hamburg, Germany, (4)Carnegie Institute for Science, Argonne, IL, United States
Carbonate melts are rare magmas with only a single active volcano (Oldoinyo Lengai,Tanzania [1]). They are of fundamental interest for their role in the Earth's deep carbon cycle and are of immense economic importance due to their affinity for REE strategic metals (niobium, uranium, tantalum, etc). They have remarkable physical properties such as very low viscosity [2] and magmatic temperatures for alkaline carbonate lavas [3] and it has been predicted that their compressibility could be significantly higher than that of silicate melts [4,5]. Despite the atomic structure of carbonate melts being fundamental for controlling their physical and chemical behavior in natural systems, very few structural studies have been reported and these have been largely computational. Here we present initial structural investigations of carbonate melts at mantle pressures using in situ x-ray diffraction in diamond anvil cells. The structure factor S(Q) is transformed to obtain the real space pair distribution function G(R) which describes the local and intermediate range atomic ordering allowing bond length and coordination number changes with pressure to be determined. [1] Krafft and Keller, Science 245:168-170, 1989 [2] Yono et al., Nat. Commun. 5:5091, 2014 [3] Dobson et al., Earth Planet. Sci. Lett. 143:207-215, 1996 [4] Genge et al., Earth Planet. Sci. Lett. 131:225-238, 1995 [5] Jones et al., Rev. Mineral. Geochem. 75:289-322, 2013