Contrasting seismic reflectivity of the lower crust and uppermost mantle between NE Japan and SW Japan as illustrated by petrophysical analyses of mafic and ultramafic xenoliths

摘要: [1] Petrophysical analyses of mafic and ultramafic xenoliths reveal large contrasts in acoustic impedance between the lower crustal rocks uppermost mantle both beneath Ichinomegata Crater NE Japan Oki-Dogo Island SW Japan. In contrast to minor among Crater, relatively are present granulite olivine gabbro as well plagioclase-bearing wehrlite other cumulus peridotites rocks. Based on existing petrologic models crust Island, we then constructed model structures these two areas, composed units with randomly arranged, 100 m thick, foliation-parallel horizontal layers xenolith samples, used examine seismic reflectivity areas. The results suggest presence strong reflectors Although no recognizable reflector is expected many due above Island. Thus a remarkable likely areas