A Paleogene magmatic overprint on Cretaceous seamounts of the western Pacific |
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| Authors: | Naoto Hirano Hirochika Sumino Taisei Morishita Shiki Machida Takaomi Kawano Kazutaka Yasukawa Takafumi Hirata Yasuhiro Kato Teruaki Ishii |
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| Affiliation: | 1. Center for Northeast Asian Studies, Tohoku University, Sendai, Japan;2. Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan;3. Hydrographic and Oceanographic Department, Japan Coast Guard, Tokyo, Japan;4. Ocean Resources Research Center for Next Generation, Chiba Institution of Technology, Chiba, Japan;5. Graduate School of Science, Tohoku University, Sendai, Japan;6. School of Engineering, The University of Tokyo, Tokyo, Japan;7. Geochemical Research Center, The University of Tokyo, Tokyo, Japan;8. Center for Integrated Research and Education of natural Hazards, Shizuoka University, Shizuoka, Japan |
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| Abstract: | The West Pacific Seamount Province (WPSP) represents a series of short-lived Cretaceous hotspot tracks. However, no intraplate volcanoes in advance of petit-spot volcanism erupted near a trench have been identified after the formation of the WPSP on the western Pacific Plate. This study reports new ages for Paleogene volcanic edifices within the northern WPSP, specifically the Ogasawara Plateau and related ridges, and Minamitorishima Island. These Paleogene ages are the first reported for basaltic rocks on western Pacific seamounts, in an area that has previously only yielded Cretaceous ages. The newly found Paleogene volcanisms overprint the Early–middle Cretaceous volcanic edifices, because the seamount or paleo-island material-covered reefal limestone caps on these edifices are uniformly older than the Paleogene volcanism identified in this study. This study outlines several possible causative factors for the Paleogene volcanism overprinting onto existing Cretaceous seamounts, including volcanism related to lithospheric stress, or a younger hotspot track within the northern part of the WPSP that records magmatism from ~60 Ma. |
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| Keywords: | alkali-basalt hotspot Pacific plate Paleogene petit-spot rejuvenation seamount |
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