2017/04/01 by Felix V. Kaminsky, Jung-Fu Lin, Jung‐Fu Lin · 1 citation
Earth and Planetary Sciences · #High-pressure geophysics and materials #Geological and Geochemical Analysis #earthquake and tectonic studies
paper · doi:10.2138/am-2017-5949
The concentrations of Fe, Al, and Ni and their distributions were determined for all known natural assemblages of ferropericlase (fPer) and bridgmanite (Bridg), coexisting as inclusions in deep-mantle diamonds from Brazil, Canada, Guinea, and South Australia. Based upon these data, it is likely that some areas within the deep lower mantle are iron-rich and differ markedly from a pyrolitic composition. In the lowermost lower mantle, Bridg is Al-rich and fPer is Ni-poor, witnessing the presence of a free metallic phase in the mineral-forming environment. The iron partitioning in the Bridg + fPer association [ KDBridg-fPer = ([Fe/Mg]Bridg)/([Fe/Mg]fPer)at] in juvenile diamond inclusions is as low as 0.1–0.2. During ascent of the diamonds with their inclusions to the surface, the KDBridg-fPereventually increases to values of 0.4–0.5 and even as high as 0.7.