Trace element partitioning on the Tinaquillo Lherzolite solidus at 1.5 GPa

摘要: The partition coefficient (D) for any trace element in the mantle is a function of pressure, temperature and phase composition, latter which controlled by relative fertility peridotite. Models melting therefore require accurate determination coefficients along peridotite solidus. We have experimentally determined clinopyroxene, orthopyroxene olivine equilibrium with melt, close to anhydrous solidus refractory Tinaquillo Lherzolite at 1.5 GPa, 1315 °C. All elements, apart from Sc, are incompatible maximum DREE DEr 0.76. elements orthopyroxene; most compatible REE Lu (DLu=0.18). Partition generally <0.005, only Ti Li moderately (DTi=0.10;DLi=0.29). Compared previous study partitioning more fertile (mid-ocean ridge basalt (MORB)-pyrolite-90, MPY-90) it shown that, fixed coefficients, especially increase increasing source fertility. DU/DTh clinopyroxene 0.86±0.02 1.49±0.03, significantly lower than ratios previously MPY-90 1.5 GPa. When compared pyroxene on 3.0 GPa, majority as pressure decreases Notable exceptions Na become increases combined effects mean that decreasing during decompression beneath mid-ocean ridges. By expressing variation D melt fraction (F), new data can be used model taking into account changes proceeds. show composition residual (or “trapped”) melts sensitive both mineralogy (i.e. garnet–lherzolite versus spinel–lherzolite) depth range over occurs. provides valuable tool interpretation inclusions. variable much less impact aggregated melts.