We developed a new sequential chemical separation technique of Sr, Nd and Pb for isotope analysis. Chemical separation of these elements with high efficiency, high purity and low chemical blank was achieved by four steps of column chromatography using extraction resins as well as cation exchange resin with small column volumes. TRU resin, used in the second step of our separation scheme, extracts rare earth elements from sample solution with high efficiency. However, we found that the retention rate of Nd and the other rare earth elements on the TRU column is sensitive to the total amount of Fe loaded on the TRU column. Therefore, controlling the sample size by means of Fe concentration is essential in achieving high recovery rate of Nd when using TRU resin. Our chemical separation technique allows analyzing Sr-Nd-Pb isotopes from small sized samples such as micro-milled silicates and several pieces of foraminiferal carbonates.

We conducted a bathymetric, subsurface, and gravity survey off the Sada-misaki Peninsula aboard the R/V Shinsei-maru KS-16-E01 cruise. The objective of the survey is detailed mapping and collection of basic geological information about the western end of Median Tectonic Line (MTL) active fault zone which is inferred to be located in the Seto Inland Sea. In the eastern side of the survey area, the bathymetry is characterized by sand wave structures. These structures are thought to be formed by strong tidal currents. In the western side of the survey area, the seafloor is rather smooth without the sand wave growth. Uneven topography and depressions probably reflect the MTL active fault zone. The bathymetry is considered to be formed by lateral fault movements. In the western side of the survey area, acoustic wave reflections of the sub-bottom profiling interpreted as a boundary between Quaternary and Pleistocene sedimentary layers were identified. The sedimentary layers were vertically displaced probably caused by faults. The MTL is associated with a steep gradient zone of gravity anomaly. There is positive anomaly along the shoreline in the southeastern side, and the gravity anomaly decreases across the tectonic line to negative gravity anomaly in the northwestern side. The gravity anomaly is suggested to reflect a deeper basement structure beneath the subsurface sedimentary layer. The basement structure inferred from the gravity anomaly profile is consistent with the half-graben crustal structure formed by the listric curving fault.

The geographical distribution and geological occurrence of diatom ooze and diatomite–diatomaceous sediments were reviewed in and around the middle-high latitude of the North Pacific Ocean including the Bering and Japan seas. Diatoms are the most abundant microfossils found in the bottom sediments of the northern North Pacific Ocean, and the marginal Bering, Okhotsk and Japan seas. The marginal basins in the middle-high latitude of the North Pacific Ocean were formed by tectonic and volcanic activities in the late Oligocene–early Miocene. The early middle Miocene diatomite intercalated with siliceous sandstone to siltstone was deposited in shallow basins. The middle-late Miocene diatomite and diatomaceous mudstone was formed by global cooling and increased primary productivity under anoxic bottom-water conditions at bathyal depths. The late Miocene to early Pliocene diatomite and diatomaceous siltstone formed under oxic bottom-water conditions is widely distributed. During the late Pliocene-Pleistocene, turbidity sands and/or silts capped and diluted the diatomaceous sediment. The timing of these changes in sedimentary facies is simultaneous in the North Pacific region.

The JAMSTEC's facilities and equipment, including research vessels, latest observation instruments, and supercomputers, enable us to approach research targets in marine and earth science both from the in-situ observations and the numerical simulations. We have developed a near real-time forecast system using Nonhydrostatic ICosahedral Atmospheric Model “NICAM” on the Earth Simulator, and operated the system in JAMSTEC intensive field campaigns. Near real-time forecasts were carried out during the research vessel “MIRAI” cruise over the Eastern Indian Ocean (MR17-08, MR15-04), as a part of an international campaign “YMC (Years of the Maritime Continent)”, led by JAMSTEC. During the “MIRAI” Arctic Ocean cruise (MR17-05C), we carried out near real-time forecasts for the polar regions for the first time, as a pilot study toward optimization of targeted observation.

We plan to improve the forecast system by thorough validations in the forthcoming campaigns in various locations on the globe.

Powered X-ray diffraction analysis is a fundamental method to quantitative analysis of mineral composition in sediments and rocks. RockJock program, which was developed by Eberl (2003) in USGS, is distributed free of charge, and is based on the Solver function in Microsoft Excel. More than 90 minerals can be determined to quantitative mineralogical composition, therefore, most of sediments and rocks retrieved by deep ocean drilling programs can be applied. It is quite easy to use the RockJock software, whereas the accuracy and the problems was not investigated enough. In addition, an approach to treat the small amount of samples and a method to evaluate amorphous bearing materials are not well established. Therefore, we report these concerns involved in RockJock programs using sediment core samples from D/V Chikyu Expedition and standard pure materials. Our results show that we can use RockJock program for small amounts of samples and amorphous bearing materials. Our results suggest that it is necessary to select the suitable condition according to the minerals composed in samples to improve the solution. We can recycle standardless XRD data measured on board D/V Chikyu for the quantitative RockJock analysis.

Shallow sub-seafloor structure in the vicinity of Iheya-Minor Ridge was acquired using Sub-Bottom Profiler equipped on R/V Kaimei in KM17-12C cruise. Normal faults and downward warping stratification indicate regional subsidence of the studied area. The profiles also suggest local-scale compression folds that may associate with the intrusive volcanism of the ridge.

We report radiolarian fossils from sedimentary rocks recovered from off southeast Boso Peninsula, central Japan to determine the age of the rocks. Rock samples were collected from sites D03 and D04 on the steep slopes close to the Katsuura Submarine Canyon using a dredge during the cruise KT-12-35. The radiolarian assemblages suggested a geologic age of 8.84–7.74 Ma (middle Late Miocene) for the site D03 (southeast slope of the Awa-Bank) and two geologic ages of 4.5–4.3 Ma (middle Pliocene) and 11.8–9.0 Ma (early Late Miocene) for the site D04 (north slope from the Katsuura Submarine Canyon). These ages correspond to depositional ages of the Amatsu Formation of the Miura Group (forearc basin deposits), the Nishizaki Formation (accretionary prism) and the Minami-Boso Group (trench slope basin deposits) exposed on the Boso Peninsula.

Shinkaia crosnieri, a galatheid crab, has ectosymbiotic bacteria on its ventral setae, and forms very dense crowds in hydrothermally active regions and seep areas. They feed on the symbiotic bacteria and do not chase other animals for predation. To study how they move and behave in jostling crowds, we developed a vital staining to mark their individuals and trace them by using a camera on a remotely operated vehicle (ROV). Among the various dyes examined, Coomasie Brilliant Blue R250 (CBB) stained the galatheid crab the darkest, and its color lasted for more than 5 months in the laboratory at 4–5°C. The ventral setae were strongly stained, while the dorsal shell was weakly stained. The stained galatheid crab survived for more than 8 months. For the in situ staining of S. crosnieri at the Iheya North hydrothermal field in the Okinawa Trough, Japan, we applied a dye solution mixture (20 L) containing CBB and Acid Blue 161 to the galatheid crab population through a funnel equipped on the ROV Hyper-Dolphin. After staining for approximately 5 minutes, more than 18 individuals of S. crosnieri were dyed blue. They were disturbed by the staining process but seemed to be unharmed. The dyed galatheid crabs were identified by the ROV one and two days post staining. They seemed to remain at the place where they were stained.

The present vital-staining marking method may present a new way to analyze the behavior and changing habitable range of deep-sea animals likeS. crosnieri, and may give us a deeper insight into how these animals behave in a very dense population and explore newer habitats.

I have developed a method to measure relative traveltimes of teleseismic P-wave between two stations as a function of frequency. The method includes an automated correction for the dispersion effects caused by the crustal reverberations at stations. Relative traveltime is computed by cross-correlating the corrected P-wave waveform at a station with that at the other station at ten narrow frequency bands from 0.03 to 0.77 Hz.

This method was applied to the seismograms including the broadband ocean-bottom seismograph (BBOBSs) data from the TIARES and Polynesian BBOBS networks in French Polynesian region and the NOMAN network in northwest Pacific Ocean. Obtained relative travel time data have been used to improve the spatial resolution in the previous seismic velocity model using finite frequency P wave traveltime tomography.

An analytical method for determining the stable isotope ratios of Ba was developed by using thermal ionization mass spectrometry (TIMS) and the ¹³⁰Ba–¹³⁵Ba double-spike total evaporation method (DS-TEV). We determined the isotope ratios of the ¹³⁰Ba–¹³⁵Ba double spike to be ¹³⁴Ba/¹³⁰Ba = 0.076623, ¹³⁵Ba/¹³⁰Ba = 1.081975, and ¹³⁷Ba/¹³⁰Ba = 0.209356 by using the intercept values of the mass-dependent fractionation lines and mixing line.

The measured repeatability of δ^137/134Ba of the National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 3104a was ±0.018‰ (2SD: 2 standard deviations, n = 7) based on the double-spike total evaporation method using thermal ionization mass spectrometry (DS-TEV-TIMS). The repeatability is comparable to or better than the best repeatability of Ba isotope ratios ever reported.

To better understand cetacean immunology, it is important to develop markers that identify specific leukocyte populations. We created a monoclonal antibody (mAb) library against leukocytes of the beluga whale (Delphinapterus leucas), and established five hybridoma clones that produce mAbs. Three of these mAbs (ID: BW-3C3, BW-2G4, and BW-2G6) react with mononuclear leukocytes including lymphocytes and monocytes. mAb BW-3C3 react to a fraction of the lymphocytes. The mAb-positive cells were identical to cells that also stained with polyclonal anti-whale IgM antibodies, indicating that the mAb BW-3C3 specifically reacts to B lymphocytes. mAb BW-2G4 specifically binds to monocytes that possess a reniformed nucleus. mAb BW-2G6 was found to bind to heterogeneous lymphocytes, namely, anti-whale IgM antibody-positive and -negative lymphocyte populations. This indicates that this mAb reacts with B and non-B lymphocyte fractions. The other two mAbs (ID: BW-4B10 and BW-4G12) react with polymorphonuclear granulocytes. Double staining with Giemsa-eosin showed that mAb BW-4B10 and mAb BW-4G12 specifically identify neutrophils and eosinophils, respectively. This panel of mAbs will be a useful tool for classifying leukocytes and for determining their localization in different tissues, which in turn would contribute to our understanding of cetacean immunology and allow evaluation of leukocyte function in infectious diseases.

We conducted marine seismic surveys using a multichannel seismic reflection (MCS) system and ocean bottom seismographs in the southern part of the Japan Sea including the western Yamato Basin, starting in 2014, as part of the research project “Integrated Research Project on Seismic and Tsunami Hazards Around the Sea of Japan” funded by the Ministry of Education, Culture, Sports, Science and Technology of Japan. The objective in these surveys is to reveal the distribution of the active faults, and the relationship between the crustal structure and the tectonic history in the southern Japan Sea. In this data paper, we describe the acquisition and processing of the MCS data obtained by these surveys.

Complete data set is available via site:

http://www.godac.jamstec.go.jp/catalog/data_catalog/metadataDisp/JAMSTEC-R_27DP01?lang=en