Japan Geoscience Union Meeting 2014

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Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS32_30PM1] Drilling Earth Science

Wed. Apr 30, 2014 2:15 PM - 4:00 PM 416 (4F)

Convener:*Saneatsu Saito(Japan Agency for Marine-Earth Science and Technology), Ken Ikehara(Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology), Tetsuro Hirono(Department of Earth and Space Science, Graduate School of Science, Osaka University), Keita Umetsu(Japan Agency for Marine-Earth Science and Technology), Chair:Ken Ikehara(Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology), Natsue Abe(Institute for Research on Earth Evolution Independent Administrative Institution Japan Agency for Marine-Earth Science and Technology)

3:00 PM - 3:15 PM

[MIS32-18] IODP Exp. 345: The first sample of primitive layered gabbros from fast-spreading lower oceanic crust

*Natsue ABE1, Norikatsu AKIZAWA2, Yumiko HARIGANE3, Takashi HOSHIDE4, Jinichiro MAEDA5, Sumiaki MACHI2, Toshio NOZAKA6, Marie PYTHON3, Kathryn GILLIS7, Jonathan SNOW8, SHIPBOARD SCIENTIFIC PARTY, Iodp expedition 345 9 (1.IFREE, JAMSTEC, 2.Department of Earth Sciences, Kanazawa University, 3.Hokkaido University, 4.Akita University, 5.AIST, 6.Okayama Univesity, 7.University of Victoria, B.C., 8.University of Houston, 9.IODP, Texas A&M University)

Keywords:layered gabbro, oceanic lower crust, Hess Deep, fast-spreading ridge, East Pacific Rise, primitive gabbro

Three-quarters of the ocean crust formed at fast-spreading ridges is composed of plutonic rocks whose mineral assemblages, textures and compositions record the history of melt transport and crystallization between the mantle and the seafloor. However, owing to the nearly continuous overlying extrusive upper crust, sampling in situ the lower crust is challenging. Hence, models for understanding the formation of the lower crust are based essentially on geophysical studies and ophiolites. Integrated Ocean Drilling Program (IODP) Expedition 345 recovered the first significant sections of primitive, modally layered gabbroic rocks from the lowermost plutonic crust formed at a fast-spreading ridge, and exposed at the Hess Deep Rift (Gillis et al., Nature, 2014, doi:10.1038/nature12778).