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41.
Atsushi ANDO Naoki MITA Shigeru TERASHIMA 《Geostandards and Geoanalytical Research》1987,11(2):159-166
During the five-year period (April 1981 - March 1986), a series of fifteen rock reference samples, "Igneous rock series", has been prepared by the Geological Survey of Japan (GSJ). Based on the data available (published and communicated), consensus values for major, minor and trace elements have been derived; these values are presented for this second series of samples as well as for the first series of two samples, Granodiorite JG-1 and Basalt JB-1. 相似文献
42.
The application of the Sr/Ca-Ba/Ca systematics to volcanic rocks of the Andean Southern Volcanic Zone (33°S–46°S) has revealed a good correlation between the estimated degree of partial melting required to generate primary magmas and the projected extensions of the oceanic Nazca plate fracture zones under the continental South American plate. Magmas erupted at volcanic centers situated above these projections are thought to have been derived from primary magmas generated by relatively high degrees of melting, whereas those erupted at other centers are thought to have evolved from magmas produced by comparatively low degree of fusion. We interpret this relationship to reflect the facilitation of heat and mass transfer from the asthenosphere below the subducted oceanic lithosphere to the subarc mantle by the fracture zones. This contribution enhances the degree of melting of the subarc mantle source as well as the fraction of material derived from the subducted oceanic crust. This model predicts the predominance of basalts depleted in incompatible trace elements in centers located above the Nazca plate fracture zone extensions and of basalts enriched in incompatible trace elements in centers situated between boundaries of fracture extensions. 相似文献
43.
Yuji Ito Toshiya Katano Naoki Fujii Masumi Koriyama Kenji Yoshino Yuichi Hayami 《Journal of Oceanography》2013,69(4):467-479
Eucampia zodiacus Ehrenberg is harmful, as it causes reduction in the quality of the aquacultured Porphyra thalli owing to nutrient depletions during dense blooms in the late winter in the macrotidal Ariake Sea, Japan. To understand the mechanism of bloom development, changes in the abundance of E. zodiacus during a bloom were investigated along vessel transects from February to April 2012. In addition, marine environmental variables were continuously monitored by the Ariake Sea Monitoring Tower, which revealed that turbidity periodically decreased during neap tides. During the 16 February neap tide, a high Secchi depth (4.3 m) was recorded at offshore stations and the Z 1% depth, at which the light intensity attenuates to 1 % of that at the sea surface, exceeded the water depth. On 16 February, the abundance of E. zodiacus was 52–732 cells mL?1, peaking at 7.0 m depth offshore. Subsequently, abundance increased at all stations. During the 22 February spring tide, abundance became vertically uniform. On 19 March, abundance at the tower reached 3758 cells mL?1 at the surface. We conclude that an improvement in light conditions in the deeper layer triggered the bloom, although the size and the duration of the bloom were determined by nutrient availability. Thus, decreases in turbidity during neap tides and subsequent strong vertical mixing during spring tides may be instrumental in the population dynamics of the large diatom E. zodiacus in macrotidal environments. 相似文献
44.
Yoshihiro Hidaka Naoki Shirai Akira Yamaguchi Mitsuru Ebihara 《Meteoritics & planetary science》2019,54(5):1153-1166
We have studied magnetic fractions of five acapulcoites, three lodranites, and two winonaites to investigate chemical compositions of their precursor materials and metallic partial melting processes occurring on their parent bodies. One winonaite metal is similar in composition to low Au, low Ni IAB iron subgroup, indicating genetic relationship between them. Magnetic fractions of chondrule‐bearing acapulcoite and winonaite have intermediate chemical compositions of metals between H chondrites and EL chondrites. This fact indicates that the precursor materials of acapulcoite–lodranites and winonaites were similar to H and/or EL chondrites in chemical compositions. Magnetic fractions in acapulcoite–lodranites have a large variety of chemical compositions. Most of them show enrichments of W, Re, Ir, Pt, Mo, and Rh, and one of them shows clear depletion in Re and Ir relative to those of chondrule‐bearing acapulcoite. Chemical compositional variations among acapulcoite–lodranite metals cannot be explained by a single Fe‐Ni‐S partial melting event, but a two‐step partial melting model can explain it. 相似文献
45.
The Neogene marine sedimentary rock area in the eastern marginal region of the Japan Sea is an area with some of the highest landslide densities in Japan. Some of the landslides in this area have been known to involve saline groundwater, which can be the cause of these landslides. In order to demonstrate the relationships between landslides and saline water, topographic, geological, groundwater, and electromagnetic surveys were performed in the eastern marginal region of the Japan Sea. Many landslides and gravitational slope deformations with linear depressions and small scarps were recognized in the study area. The resistivity profile obtained by an electromagnetic survey suggests that there is a wide zonal distribution of saline water with salt concentrations equivalent to seawater at depths of 50–100 m or more and that the groundwater shallower than 50 m has an electrical conductivity of less than 100 mS/m. The shallow resistive groundwater is inferred to be meteoric water that replaced the saline groundwater, which likely weakened the bedrock, resulting in landslides. A ridge of competent tuff overlying mudstone has many linear depressions from gravitational slope deformation and low‐resistivity water to a depth of 600 m, which suggests that the mudstone was weakened by water replacement and deformed under the tuff caprock. The saline groundwater is inferred to be fossil seawater trapped in pores during sediment deposition, which is brought near the ground surface along with rocks by tectonic movement in the hills. Thus, the saline water and its fresh water replacement are among the important basic causes of the landslides. The oil well data obtained in the eastern marginal region of the Japan Sea suggest that such saline water replacement has occurred widely and that replacement is likely one of the predispositions for the frequent landslides there. 相似文献
46.
Hideyuki Kawamura Toshimichi Ito Naoki Hirose Tetsutaro Takikawa Jong-Hwan Yoon 《Journal of Oceanography》2009,65(4):439-454
The branches of the Tsushima Warm Current (TWC) are realistically reproduced using a three-dimensional ocean general circulation
model (OGCM). Simulated structures of the First Branch and the Second Branch of the TWC (FBTWC and SBTWC) in the eastern Japan
Sea are mainly addressed in this study, being compared with measurement in the period September–October 2000. This is the
first numerical experiment so far in which the OGCM is laterally exerted by real volume transports measured by acoustic Doppler
current profiler (ADCP) through the Tsushima Straits and the Tsugaru Strait. In addition, sea level variation measured by
tide-stations along the Japanese coast as well as satellite altimeters is assimilated into the OGCM through a sequential data
assimilation method. It is demonstrated that the assimilation of sea level variation at the coastal tide-stations is useful
in reproducing oceanic conditions in the nearshore region. We also examine the seasonal variation of the branches of the TWC
in the eastern Japan Sea in 2000. It is suggested as a consequence that the FBTWC is continuous along northwestern Honshu
Island in summertime, while it degenerates along the coast between the Sado Strait and the Oga Peninsula in other seasons.
On the other hand, a mainstream of the SBTWC exists with meanders and eddies in the offshore region deeper than 1000 m to
the north of the Sado Island throughout the year. 相似文献
47.
Naoki Tanimata Orio Yamamura Yasunori Sakurai Tomonori Azumaya 《Journal of Oceanography》2008,64(2):185-194
The food habits of the dominant myctophid Stenobrachius leucopsarus were examined in the central basin of the Bering Sea in relation to oceanographic conditions, in summer 2002 and 2003 and
spring 2006. S. leucopsarus exhibited an ontogenetic and seasonal dietary shift. In spring, small fish (≤40 mm) preyed mainly on Neocalanus flemingeri/plumchrus whereas large fish fed mainly on Neocalanus cristatus. In summer, small fish preyed mainly on Metridia pacifica whereas large fish fed mainly on euphausiids (Thysanoessa spp.). In the summer of 2003, when water temperature in the epipelagic layer (≤100 m) was warmer, reflecting the prevalence
of the Alaskan Stream, small-sized S. leucopsarus showed a higher stomach content index, perhaps reflecting the greater abundance of M. pacifica. Thus, the present study shows that the physical variability in the epipelagic layer affects not only diets but also feeding
performance of micronekton. 相似文献
48.
Fumiaki Nakata Tadayuki Kodama Kazuhiro Shimasaku Mamoru Doi Hisanori Furusawa Masaru Hamabe Masahiko Kimura Yutaka Komiyama Satoshi Miyazaki Sadanori Okamura Masami Ouchi † Maki Sekiguchi Yoshihiro Ueda Masafumi Yagi Naoki Yasuda 《Monthly notices of the Royal Astronomical Society》2005,357(4):1357-1362
49.
Naoki Yoshida † Ravi K. Sheth Antonaldo Diaferio 《Monthly notices of the Royal Astronomical Society》2001,328(2):669-677
We use numerical simulations of a (480 Mpc h −1 )3 volume to show that the distribution of peak heights in maps of the temperature fluctuations from the kinematic and thermal Sunyaev–Zeldovich (SZ) effects will be highly non-Gaussian, and very different from the peak-height distribution of a Gaussian random field. We then show that it is a good approximation to assume that each peak in either SZ effect is associated with one and only one dark matter halo. This allows us to use our knowledge of the properties of haloes to estimate the peak-height distributions. At fixed optical depth, the distribution of peak heights resulting from the kinematic effect is Gaussian, with a width that is approximately proportional to the optical depth; the non-Gaussianity comes from summing over a range of optical depths. The optical depth is an increasing function of halo mass and the distribution of halo speeds is Gaussian, with a dispersion that is approximately independent of halo mass. This means that observations of the kinematic effect can be used to put constraints on how the abundance of massive clusters evolves, and on the evolution of cluster velocities. The non-Gaussianity of the thermal effect, on the other hand, comes primarily from the fact that, on average, the effect is larger in more massive haloes, and the distribution of halo masses is highly non-Gaussian. We also show that because haloes of the same mass may have a range of density and velocity dispersion profiles, the relation between halo mass and the amplitude of the thermal effect is not deterministic, but has some scatter. 相似文献
50.