Site 798

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doi:10.2973/odp.proc.ir.128.105.1990

Cited by 4 publications

References 49 publications

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Diatom records in the Quaternary marine sequences around the Japanese Islands

Koizumi

Yamamoto

2016

Quaternary International

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Understanding the Quaternary is a key to estimating what the Earth's climate will be like in the future. Such studies demand high-resolution analyses based on the paleoclimatic proxy records of changing the Earth's orbital forcing and solar insolation that affect the climate system. Quaternary diatom biostratigraphy and paleoceanography have been well established based on the Quaternary marine sequences obtained by piston coring and deep-sea drilling around the Japanese Islands. This paper firstly reviews the Quaternary diatom datum levels that are directly tied to magnetic polarity, and then the late Pleistocene and Holocene rhythmic fluctuations in

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Diatom records in the Quaternary marine sequences around the Japanese Islands

Koizumi

Yamamoto

2016

Quaternary International

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Expedition 346 summary

Tada¹,

Murray²,

Zarikian³

et al. 2015

Proceedings of the IODP

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Integrated Ocean Drilling Program (IODP) Expedition 346 (29 July-27 September 2013) drilled seven sites covering a wide latitudinal range in the body of water bordered by the Eurasian continent, the Korean Peninsula, and the Japanese Islands, as well as two closely spaced sites in the East China Sea. This expedition recovered 6135.3 m of core with an average recovery of 101%-a record amount of core recovered during any single IODP expedition. Expedition 346 was the first scientific drilling expedition ever to focus exclusively on the climate system in this region, which is at once so critical yet potentially vulnerable to the challenges society faces in the coming years of global climate change. With the East Asian Monsoon directly affecting the water supply of one-third of the global population, the expedition scientific results and postexpedition research that will follow have direct bearing on society's understanding of this complex atmosphereocean climate system. The high quality of materials recovered and the complete documentation of their geological, geochemical, and geophysical context will lead to an unparalleled series of future studies by the expedition Science Party as well as many other scientists over the coming decades. Cores obtained during this expedition will be used to test the hypothesis that Pliocene-Pleistocene uplift of the Himalaya and Tibetan Plateau, and the consequent emergence of the two discrete modes of Westerly Jet circulation, caused the amplification of millennial-scale variability of the East Asian summer monsoon and East Asian winter monsoon and provided teleconnection mechanism(s) for Dansgaard-Oeschger cycles.Recent and novel advances in drilling technology and newly developed analytical tools enabled collection and examination of sediment records that were impossible to acquire even a few years ago. The newly engineered half advanced piston corer enabled recovery of the deepest piston core in Deep Sea Drilling Project/ Ocean Drilling Program/IODP history (490.4 m in IODP Hole U1427A); that achievement was also the deepest continuously recovered piston cored sequence, initiated at the mudline and penetrating to ~500 m core depth below seafloor, Method A (CSF-A). Technological advances delivered a series of "new surprises" (e.g., pristine dark-light laminae from ~12 Ma sediment recovered by piston core from 410 m CSF-A at IODP Site U1425 and from 210 m CSF-A at IODP Site U1430) that will stimulate new scientific in-

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Site U1426

Tada¹,

Murray²,

Zarikian³

et al. 2015

Proceedings of the IODP

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Four holes were cored at Site U1426 (proposed Site YB-2) using the full and half advanced piston corer (APC) and the extended core barrel (XCB) (Table T1; see also Fig. F2 in the "Expedition 346 summary" chapter [Tada et al., 2015a]). Holes U1426A, U1426B, U1426C, and U1426D were cored to 396.7, 34.7, 204.0, and 99.4 m CSF-A (see the "Methods" chapter [Tada et al., 2015b]) and recovered 418.78, 35.82, 211.89, 103.71 m of core, respectively. A total of 95 APC and 2 XCB cores obtained 770.2 m of sediment (104.8% recovery). The advanced piston corer temperature tool (APCT-3) was deployed four times. Transit from Site U1425The 148 nmi transit to Site U1426 was covered in 13.4 h at an average speed of 11 kt. Sea passage ended at 0636 h on 3 September 2013. The vessel was maneuvered over the location coordinates, thrusters were lowered into position, and the vessel was turned over to dynamic positioning control. By 0715 h, the vessel was stabilized for rig floor operations to begin. A Falmouth Scientific positioning beacon (model BAP-547; SN1028W, 16 KHz, 206 dB) was deployed at 0822 h. Hole U1426AA three-stand APC/XCB bottom-hole assembly was assembled, and the drill string was run to the seafloor. After picking up the top drive and spacing out the drill string to 907.4 meters below rig floor (mbrf), which was 6.0 m deeper than the depth provided by the precision depth recorder, an APC core barrel was deployed. The first core barrel recovered 2.47 m of core, establishing a seafloor depth of 914.4 mbrf. Oriented APC coring continued using full-length nonmagnetic core barrels through Core 346-U1426A-28H at 256.2 m CSF-A. At this depth, the APC was switched to the half APC (4.7 m) system, and coring continued through Core 37H (297.0 m CSF-A), where a solid dolomite layer was encountered. The XCB was picked up and used to cut a 1.0 m core (38X) until breaking through the layer of resistance. Half APC coring resumed from that point and continued through Core 59H (396.7 m CSF-A). The hole was displaced with 160 bbl of 10.5 ppg mud. The top drive was set back, and the drill string was pulled clear of the seafloor at 2330 h on 4 September 2013, ending Hole U1426A. Total recovery for this hole was 418.78 m (105.6%). A total of 29 half APC cores were recovered. Four successful temperature measurements were taken using the APCT-3 temperature shoe at 31.0, 59.5, 88.0, and 116.5 m CSF-A, respectively.

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Site 798

Cited by 4 publications

References 49 publications

Diatom records in the Quaternary marine sequences around the Japanese Islands

Diatom records in the Quaternary marine sequences around the Japanese Islands

Expedition 346 summary

Site U1426

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