Workshop report on hard-rock drilling into mid-Cretaceous Pacific oceanic crust on the Hawaiian North Arch

Workshop report on hard-rock drilling into mid-Cretaceous Pacific oceanic crust on the Hawaiian North Arch

<p>The architecture, formation, and modification of oceanic plates are fundamental to our understanding of key geologic processes of the Earth. Geophysical surveys were conducted around a site near the Hawaiian Islands (northeastern Hawaiian North Arch region; Hawaiian North Arch hereafter), w...

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Main Authors: T. Morishita, S. Umino, J.-I. Kimura, M. Yamashita, S. Ono, K. Michibayashi, M. Tominaga, F. Klein, M. O. Garcia
Format: Article
Language:English
Published: Copernicus Publications 2019-12-01
Series:Scientific Drilling
Online Access:https://www.sci-dril.net/26/47/2019/sd-26-47-2019.pdf
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spelling doaj-f56450ae6de74b4b8c2434b933fdfa032020-11-25T02:05:27ZengCopernicus PublicationsScientific Drilling 1816-89571816-34592019-12-0126475810.5194/sd-26-47-2019Workshop report on hard-rock drilling into mid-Cretaceous Pacific oceanic crust on the Hawaiian North ArchT. Morishita0T. Morishita1S. Umino2J.-I. Kimura3M. Yamashita4M. Yamashita5S. Ono6K. Michibayashi7M. Tominaga8F. Klein9M. O. Garcia10School of Geosciences and Civil Engineering, College of Science and Engineering, Kanazawa University, Kanazawa, Ishikawa 920-1192, JapanLamont-Doherty Earth Observatory, Columbia University, New York, NY 10027, USASchool of Geosciences and Civil Engineering, College of Science and Engineering, Kanazawa University, Kanazawa, Ishikawa 920-1192, JapanVolcanoes and Earth's Interior Research Center, Research Institute for Marine Geodynamics, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima, Yokosuka, Kanagawa 237-0061, JapanTectonics and Resources Research Group, Research Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8567, JapanSubduction Dynamics Research Center, Research Institute for Marine Geodynamics (IMG), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 3173-25, Showa-machi, Kanazawa, Yokohama, Kanagawa 236-0001, JapanVolcanoes and Earth's Interior Research Center, Research Institute for Marine Geodynamics, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima, Yokosuka, Kanagawa 237-0061, JapanDepartment of Earth Planetary Sciences, Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8601, JapanDepartment of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USADepartment of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USADepartment of Earth Sciences, University of Hawai`i at Mānoa, Honolulu, HI 96822, USA<p>The architecture, formation, and modification of oceanic plates are fundamental to our understanding of key geologic processes of the Earth. Geophysical surveys were conducted around a site near the Hawaiian Islands (northeastern Hawaiian North Arch region; Hawaiian North Arch hereafter), which is one of three potential sites for an International Ocean Discovery Program mantle drilling proposal for the Pacific plate that was submitted in 2012. The Hawaiian North Arch site is located in 78–81&thinsp;Ma Cretaceous crust, which had an estimated full spreading rate of 7–8&thinsp;cm&thinsp;yr<span class="inline-formula"><sup>−1</sup></span>. This site fills a major gap in our understanding of oceanic crust. Previously drilling has been skewed to young or older crust (<span class="inline-formula">&lt;15</span> or <span class="inline-formula">&gt;110</span>&thinsp;Ma) and slow-spread crust. P-wave velocity structure in the uppermost mantle of the Hawaiian North Arch shows a strong azimuthal anisotropy, whereas Moho reflections below the basement are variable: strong and continuous, weak, diffuse, or unclear. We assume that the strength of the Moho reflection is related to the aging of the oceanic plate. The Hawaiian volcanic chain (200&thinsp;km to the southwest of the proposed drill site) and the nearby North Arch magmatism on the proposed Hawaiian North Arch sites might also have affected recognition of the Moho via deformation and/or magma intrusion into the lower crust of the uppermost mantle. This workshop report describes scientific targets for 2&thinsp;km deep-ocean drilling in the Hawaiian North Arch region in order to provide information about the lower crust from unrecovered age and spreading rate gaps from previous ocean drillings. Other scientific objectives to be achieved by drilling cores before reaching the target depth of the project are also described in this report.</p>https://www.sci-dril.net/26/47/2019/sd-26-47-2019.pdf
collection DOAJ
language English
format Article
sources DOAJ
author T. Morishita
T. Morishita
S. Umino
J.-I. Kimura
M. Yamashita
M. Yamashita
S. Ono
K. Michibayashi
M. Tominaga
F. Klein
M. O. Garcia
spellingShingle T. Morishita
T. Morishita
S. Umino
J.-I. Kimura
M. Yamashita
M. Yamashita
S. Ono
K. Michibayashi
M. Tominaga
F. Klein
M. O. Garcia
Workshop report on hard-rock drilling into mid-Cretaceous Pacific oceanic crust on the Hawaiian North Arch
Scientific Drilling
author_facet T. Morishita
T. Morishita
S. Umino
J.-I. Kimura
M. Yamashita
M. Yamashita
S. Ono
K. Michibayashi
M. Tominaga
F. Klein
M. O. Garcia
author_sort T. Morishita
title Workshop report on hard-rock drilling into mid-Cretaceous Pacific oceanic crust on the Hawaiian North Arch
title_short Workshop report on hard-rock drilling into mid-Cretaceous Pacific oceanic crust on the Hawaiian North Arch
title_full Workshop report on hard-rock drilling into mid-Cretaceous Pacific oceanic crust on the Hawaiian North Arch
title_fullStr Workshop report on hard-rock drilling into mid-Cretaceous Pacific oceanic crust on the Hawaiian North Arch
title_full_unstemmed Workshop report on hard-rock drilling into mid-Cretaceous Pacific oceanic crust on the Hawaiian North Arch
title_sort workshop report on hard-rock drilling into mid-cretaceous pacific oceanic crust on the hawaiian north arch
publisher Copernicus Publications
series Scientific Drilling
issn 1816-8957
1816-3459
publishDate 2019-12-01
description <p>The architecture, formation, and modification of oceanic plates are fundamental to our understanding of key geologic processes of the Earth. Geophysical surveys were conducted around a site near the Hawaiian Islands (northeastern Hawaiian North Arch region; Hawaiian North Arch hereafter), which is one of three potential sites for an International Ocean Discovery Program mantle drilling proposal for the Pacific plate that was submitted in 2012. The Hawaiian North Arch site is located in 78–81&thinsp;Ma Cretaceous crust, which had an estimated full spreading rate of 7–8&thinsp;cm&thinsp;yr<span class="inline-formula"><sup>−1</sup></span>. This site fills a major gap in our understanding of oceanic crust. Previously drilling has been skewed to young or older crust (<span class="inline-formula">&lt;15</span> or <span class="inline-formula">&gt;110</span>&thinsp;Ma) and slow-spread crust. P-wave velocity structure in the uppermost mantle of the Hawaiian North Arch shows a strong azimuthal anisotropy, whereas Moho reflections below the basement are variable: strong and continuous, weak, diffuse, or unclear. We assume that the strength of the Moho reflection is related to the aging of the oceanic plate. The Hawaiian volcanic chain (200&thinsp;km to the southwest of the proposed drill site) and the nearby North Arch magmatism on the proposed Hawaiian North Arch sites might also have affected recognition of the Moho via deformation and/or magma intrusion into the lower crust of the uppermost mantle. This workshop report describes scientific targets for 2&thinsp;km deep-ocean drilling in the Hawaiian North Arch region in order to provide information about the lower crust from unrecovered age and spreading rate gaps from previous ocean drillings. Other scientific objectives to be achieved by drilling cores before reaching the target depth of the project are also described in this report.</p>
url https://www.sci-dril.net/26/47/2019/sd-26-47-2019.pdf
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