Sakamoto, Tatsuhiko; Saito, Saneatsu; Shimada, Chieko; Yamane, Masayuki (2003): Core-log integration of natural gamma ray intensity to construct a 10-m.y. continuous sedimentary record off Sanriku, western Pacific margin, ODP sites 1150 and 1151. Texas A&M University, Ocean Drilling Program, College Station, TX, United States, In: Suyehiro, Kiyoshi, Sacks, I. Selwyn, Acton, Gary D., Acierno, Michael J., Araki, Eiichiro, Ask, Maria V. S., Ikeda, Akihiro, Kanamatsu, Toshiya, Kim, Gil Young, Li, Jingfen, Linde, Alan T., McWhorter, Paul N., Mora, German, Najman, Yanina M. R., Niitsuma, Nobuaki, Pandit, Benoy K., Roller, Sybille, Saito, Saneatsu, Sakamoto, Tatsuhiko, Shinohara, Masanao, Sun, Yue-Feng, Proceedings of the Ocean Drilling Program, scientific results, Western Pacific geophysical observatories; covering Leg 186 of the cruises of drilling vessel JOIDES Resolution; Yokohama, Japan, to Yokohama, Japan; sites 1150 and 1151, 14 June-14 August 1999, 186, georefid:2004-011525

Abstract:
Detection of climate response to orbital forcing during Cenozoic long-term global cooling is a key to understanding the behavior of Earth's icehouse climate. Sedimentary rhythm, which is a rhythmic or cyclic variation in the sequence of sediments and sedimentary rocks, is useful for quantitative reconstruction of Earth's evolution during geological time. In this study, we attempt to (1) identify sources of natural gamma ray (NGR) emissions of core recovered during Ocean Drilling Program (ODP) Leg 186 by analyses of physical properties, major element concentrations, diatom abundances, and total organic carbon contents, (2) integrate whole-core NGR intensity of recovered core with wireline logging NGR measurements in order to construct a continuous sedimentary sequence, and (3) discuss changes in the NGR signal in the time domain. This attempt gives us preliminary information to discuss climate stability in relation to orbital forcing thorough geologic time. NGR values are obtained mainly by indirectly measuring the amount of terrigenous minerals including potassium and related elements in the sediments. NGR intensity is also affected by high porosity, which in these sediments was related to the amount of diatom valves. NGR signals might be a proxy of the intensity of the East Asian monsoon off Sanriku. A continuous sedimentary record was constructed by integration of the whole-core NGR intensity measured in sediments obtained from the drilled holes with that measured directly in the borehole by wireline logging, then using a stratigraphic age model to convert to a time series covering 1.3-9.7 Ma with a short break at approximately 5 Ma. High sedimentation rate (H) stages were identified in the sequence, related to intervals of low-amplitude precession and eccentricity variations. The transition of the dominant periodicities through the four H stages may correlate to major shifts in the climate system, including the onset of major Northern Hemisphere glaciation, the initial stage of the East Asian monsoon intensification, and the onset of the East Asian monsoon with uplift of the Himalayas and the Tibetan Plateau.
Coverage:
West: 143.2000 East: 143.2000 North: 39.1100 South: 38.4500
Relations:
Expedition: 186
Site: 186-1150
Site: 186-1151
Supplemental Information:
Available only on CD-ROM in PDF format and on the Web in PDF or HTML
Data access:
Provider: SEDIS Publication Catalogue
Data set link: http://sedis.iodp.org/pub-catalogue/index.php?id=10.2973/odp.proc.sr.186.112.2003 (c.f. for more detailed metadata)
Data download: application/pdf
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