[SCG64-10] The Renaissance of the Oldest Oceanic Plate: Jurassic Oceanic Crust without Moho
Keywords:Moho reflections, MORB, hydrous melting
Kaneda et al. (2010) conducted seismic surveys across the Marcus-Wake seamount chain. They found two contrasting sub-seafloor structures in the Jurassic lithosphere. The southern basin is underlain by 7.5-8.0 km thick crust with clear Moho reflections (sharp, single, flat and continuous, and of large amplitude. Beneath the northern basin, in contrast, the Moho reflections, if there at all, are extremely weak, and crust is only 6 km thick. The correlation between the strength of the Moho reflections and crustal thicknesses has been observed in other seismic profiles in the Pacific Plate (e.g. Ohira et al., 2017). We suggest that two types of oceanic crust exist; one thick with a Moho and the other thin without a Moho (Tamura et al., in prep). MORB overlying clear Moho reflections have been recovered at Site 801and thus Site MINA has been selected to represent Jurassic oceanic crust without the Moho.