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.

*Ikuya Nishio1, Tomoaki Morishita1, Akihiro Tamura1, Juan Miguel Ramirez Guotana1, Kenichiro Tani2, Yumiko Harigane3, Kristoffer Szilas4, D. Graham Pearson5 (1.Kanazawa University, 2.Department of Geology and Paleontology, National Museum of Nature and Science, 3.Institute of Geology and Geoinformation Geological Survey of Japan/AIST, 4.University of Copenhagen, 5.University of Alberta)

*Yasuhiro Hirai1,2, Yoshihiko Tamura2, Kaj Hoernle3, Reinhard Werner3, Folkmar Hauff3, Christian Timm4, Bogdan Vaglarov2, Qing Chang2, Takashi Miyazaki2, Jun-Ichi Kimura2, Takeshi Hanyu2 (1.Graduate School of Natural Science and Technology, Kanazawa University, Japan, 2.Research Institute for Marine Geodynamics (IMG), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Kanagawa, Japan, 3.GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany, 4.GNS Science, Lower Hutt, New Zealand)

*Yasuhiko Ohara1,2,3, Kyoko Okino4, Norikatsu Akizawa4, Masakazu Fujii5, Yumiko Harigane6, Ken-ichi Hirauchi7, Osamu Ishizuka6, Shiki Machida8, Katsuyoshi Michibayashi3, Alessio Sanfilippo9, Sani Camilla9, Snow E. Jonathan10, Kenichiro Tani11, Hiroyuki Yamashita12 (1.Hydrographic and Oceanographic Department of Japan, 2.Japan Agency for Marine-Earth Science and Technology , 3.Nagoya University, 4.Atmosphere and Ocean Research Institute, University of Tokyo, 5.National Institute of Polar Research , 6.Geological Survey of Japan, AIST, 7.Shizuoka University, 8.Chiba Institute of Technology, 9.University of Pavia, 10.Louisiana State University, 11.National Science Museum, 12.Kanagawa Prefectural Museum of Natural History)