JpGU-AGU Joint Meeting 2020

Session information

[E] Oral

S (Solid Earth Sciences ) » S-CG Complex & General

[S-CG64] Crust-mantle connections

convener:Yoshihiko Tamura(Research Institute for Marine Geodynamics, Japan Agency for Maine-Earth Science and Technology), Osamu Ishizuka(Geological Survey of Japan, AIST)

The western portion of the Pacific Plate, the oldest oceanic plate in the world, has been drilled several times and, based on Ocean Drilling Program (ODP) Site 801, an understanding of its layers, from pelagic clay through chert to alkali basalts and tholeiitic mid-ocean ridge basalts (MORB), has been established. This oldest oceanic plate is experiencing a renaissance and we propose a strategy to drill the most suitable three sites to recover specific parts of the plate to continue its renaissance. This submitted IODP preproposal is entitled The Renaissance of the Oldest Oceanic Plate: REY (Rare Earth elements and Yttrium) rich Mud, Radiolarite of Jurassic-Cretaceous Boundary (JKB), and Jurassic Oceanic Crust without Moho. The drilling sites, MM, MAT, and MINA, target (1) the most complete sedimentary sequence of pelagic clay including REY-rich mud, (2) newly found outcrops of the Jurassic-Cretaceous boundary (JKB), and (3) MORB tholeiites without Moho, respectively. This session invite scientists who are interested in these exciting drillings.
It is common knowledge that the Moho is the boundary between the crust and the Earths mantle, discovered by and named after the Croatian seismologist Andrija Mohorovicic. The oceanic Moho is defined by seismic reflection images, but seismic profiles generally show that Moho reflections are not universal. Where the Moho can be detected clearly the crust is thicker. A good example is the profile from Kaneda et al. (2010) near Minami-Tori Shima, which is the main motivation for drilling at Site MINA. The session also seeks to explore the crust-mantle connections among ophiolites, at divergent and convergent plate boundaries and ocean island settings based on petrology, geochemistry, geophysics, geochronology, and geodynamics studies.

*Erika Tanaka1, Kazutaka Yasukawa2,1,3, Kentaro Nakamura1, Junichiro Ohta2,3, Tatsuo Nozaki4,2,5,3, Yoichi Usui4, Koichiro Fujinaga3,2, Koichi Iijima4, Yasuhiro Kato2,1,3 (1.Department of Systems Innovation, School of Engineering, The University of Tokyo, 2.Frontier Research Center for Energy and Resources, School of Engineering, The University of Tokyo, 3.Ocean Resources Research Center for Next Generation, Chiba Institute of Technology, 4.Submarine Resources Research Center, Japan Agency for Marine-Earth Science and Technology, 5.Department of Planetology, Faculty of Science, Kobe University)

*Tatsuji Nishizawa1, Hitomi Nakamura2,3,4,5, Hikaru Iwamori3,4,6 (1.Volcanic Fluid Research Center, School of Science, Tokyo Institute of Technology, 2.Institute of Earthquake and Volcano Geology, Geological Survey of Japan, AIST, 3.Department of Solid Earth Geochemistry, Japan Agency for Marine-Earth Science and Technology, 4.Depeartment of Earth and Planetary Sciences, School of Science, Tokyo Institute of Technology, 5.ORCeNG, Chiba Institute of Technology, 6.Earthquake Research Institute, The University of Tokyo)