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| Matsu’ura, Tabito; Ikehara, Minoru; Ueno, Tatsuyuki. |
| We investigated the deep-sea sedimentary sequence of core MD012422 corresponding to the last 350 ka (since marine isotopic stage, MIS 10) from off Shikoku Island, NW Pacific Ocean, and refined its tephrostratigraphy. We detected many tephras and cryptotephras and correlated them with terrestrial tephras on the basis of the major- and trace-element compositions of their glass shards. Then we cross-checked our results against the reported marine tephrostratigraphy in the NW Pacific area and assessed the relative timing of tephra eruptions and bioevents. Many widespread tephras and cryptotephras originated from the Kyushu volcanic zone (Kuju, Aso, Kakuto, Aira, Ata, and Kikai volcanoes/calderas), along with the Takayama-Ng1 tephra (Tky-Ng1) from Suiendani... |
| Tipo: Text |
Palavras-chave: Late Quaternary; Deep-sea sediments; Tephra; Glass shard; Major-element composition; Trace-element composition; Oxygen isotopic stratigraphy; Calcareous biostratigraphy; North Pacific. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00681/79355/81861.pdf |
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| Moriwaki, Hiroshi; Suzuki, Takehiko; Murata, Masanori; Ikehara, Minoru; Machida, Hiroshi; Lowe, David J.. |
| Two prominent tephras, Sakurajima-Satsuma (Sz-S) erupted from Sakurajima volcano and Noike-Yumugi (N-Ym) erupted from Kuchierabujima Island, provide new key marker beds for dating and synchronizing palaeoenvironmental and archaeological records in the last deglaciation in southern Japan. These tephras were identified on the basis of glass major-element compositions in two distal areas, a marine core (IMAGES MD982195) in the northern part of the East China Sea and on the central part of Tanegashima Island, and we related their stratigraphic positions to the marine oxygen isotope-based chronology. In MD982195, Sz-S, 0.8 cm in thickness at 9.12 m depth and N-Ym, 3 cm in thickness at 9.30 m depth, are both white, vitric, ash-grade tephras. On Tanegashima... |
| Tipo: Text |
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| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00226/33774/82664.pdf |
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| Rella, Stephan F.; Tada, Ryuji; Nagashima, Kana; Ikehara, Minoru; Itaki, Takuya; Ohkushi, Ken'Ichi; Sakamoto, Tatsuhiko; Harada, Naomi; Uchida, Masao. |
| Millennial-scale variability in the behavior of North Pacific Intermediate Water during the last glacial and deglacial period, and its association with Dansgaard-Oeschger (D-O) cycles and Heinrich events, are examined based on benthic foraminiferal oxygen and carbon isotopes (delta O-18(bf) and delta C-13(bf)) and %CaCO3 using a sediment core recovered from the northeastern slope of the Bering Sea. A suite of positive delta O-18(bf) excursions at intermediate depths of the Bering Sea, which seem at least in part associated with increases in the delta O-18(bf) gradients between the Bering and Okhotsk Seas, suggest the Bering Sea as a proximate source of intermediate water during several severe stadial episodes in the last glacial and deglacial period.... |
| Tipo: Text |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00265/37642/36754.pdf |
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| Orme, Lise C; Crosta, Xavier; Miettinen, Arto; Divine, Dmitry V; Husum, Katrine; Isaksson, Elisabeth; Wacker, Lukas; Mohan, Rahul; Ther, Olivier; Ikehara, Minoru. |
| Centennial and millennial scale variability of Southern Ocean temperature is poorly known, due to both short instrumental records and sparsely distributed high-resolution temperature reconstructions, with evidence for past temperature variability instead coming mainly from ice core records. Here we present a high-resolution (~ 60 year), diatom-based sea-surface temperature (SST) reconstruction from the western Indian sector of the Southern Ocean that spans the interval 14.2 to 1.0 ka BP (calibrated kiloyears before present). During the late deglaciation, the new SST record shows cool temperatures at 14.2–12.9 ka BP and gradual warming between 12.9–11.6 ka BP in phase with atmospheric temperature evolution. This supports that the temperature of the Southern... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00631/74327/73963.pdf |
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