Loveringite-davidite members of the crichtonite group were synthesized at 7.5 kbar, 1000-1050oC, from a melt of TiO2 and REE-enriched basaltic andesite composition. Four sets of partition coefficients were obtained for La, Sm, Ho, Lu and Sr (analogue for Eu2+); these show that light and heavy REE are readily accommodated, but that the intermediate REE are discriminated against in this structure. This confirms the proposed substitution of the REE in the two sites (A and M) in the minerals of the crichtonite group (AM21O38). These minerals are stable to 20 kbar, 1300oC and 30 kbar, 1000oC, indicating that this phase may be an important accessory repository for both light and heavy REE in the upper mantle.-R.A.H.
|Number of pages||5|
|Publication status||Published - 1987|