Assessment of the level of activity of advective transport through fractures and faults in marine deposits by comparison between stable isotope compositions of fracture and pore waters     

Mochizuki  Akihito  Ishii  Eiichi 《Hydrogeology Journal》2022,30(3):813-827

Hydrogeology Journal - Assessment of the level of activity of advective transport through faults and fractures is essential for guiding the geological disposal of radioactive waste. In this study,...  相似文献   

Erratum to “Regionality of deep low-frequency earthquakes associated with subduction of the Philippine Sea plate along the Nankai Trough,Southwest Japan” [Earth Planet. Sci. Lett. 272 (2008) 189–198]     

Shoichi Yoshioka  Mamiko Toda  Junichi Nakajima 《Earth and Planetary Science Letters》2009,277(1-2):292

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Regionality of deep low-frequency earthquakes associated with subduction of the Philippine Sea plate along the Nankai Trough, southwest Japan     

Shoichi Yoshioka  Mamiko Toda  Junichi Nakajima 《Earth and Planetary Science Letters》2008,272(1-2):189-198

The Fukuoka District Meteorological Observatory recently logged three possible deep low-frequency earthquakes (LFEs) beneath eastern Kyushu, Japan, a region in which LFEs and low-frequency tremors have never before been identified. To assess these data, we analyzed band-pass filtered velocity seismograms and relocated LFEs and regular earthquakes using the double-difference method. The results strongly suggest that the three events were authentic LFEs, each at a depth of about 50 km. We also performed relocation analysis on LFEs recorded beneath the Kii Peninsula and found that these LFEs occurred near the northwest-dipping plate interface at depths of approximately 29–38 km. These results indicate that LFEs in southwest Japan occur near the upper surface of the subducting Philippine Sea (PHS) plate. To investigate the origin of regional differences in the occurrence frequency of LFEs in western Shikoku, the Kii Peninsula, and eastern Kyushu, we calculated temperature distributions associated with PHS plate subduction. Then, using the calculated thermal structures and a phase diagram of water dehydration for oceanic basalt, the water dehydration rate (wt.%/km), which was newly defined in this study, was determined to be 0.19, 0.12, and 0.08 in western Shikoku, the Kii Peninsula, and eastern Kyushu, respectively; that is, the region beneath eastern Kyushu has the lowest water dehydration rate value. Considering that the Kyushu–Palau Ridge that is subducting beneath eastern Kyushu is composed of tonalite, which is low in hydrous minerals, this finding suggests that the regionality may be related to the amount of water dehydration associated with subduction of the PHS plate and/or differences in LFE depths. Notable dehydration reactions take place beneath western Shikoku and the Kii Peninsula, where the depth ranges for dehydration estimated by thermal modeling agree well with those for the relocated LFEs. The temperature range in which LFEs occur in these regions is estimated to be 400–500 °C.  相似文献   

Tectonic setting of the Azores Plateau deduced from a OBS survey   总被引：1，自引：0，他引：1  

Miranda  J.M.  Mendes Victor  L.A.  Simões  J.Z.  Luis  J.F.  Matias  L.  Shimamura  H.  Shiobara  H.  Nemoto  H  Mochizuki  H.  Hirn  A.  Lépine  J.C. 《Marine Geophysical Researches》1998,20(3):171-182

The studies of Azores seismicity generally show shocks with either normal faulting or right-lateral strike-slip along the ESE direction, compatible with a eastward relative motion of the Eurasian (EU) relative to the African (AF) plate. However, the 1 January 1980 earthquake was interpreted as a clear left-lateral strike-slip shock along the N150E direction. This pattern is difficult to explain in terms of the relative motion between the EU, AF and North American (NA) plates: all available models for the present day movement of this triple junction fail to explain the regional variability in the stress conditions of the area. Here we present data from a 34-day long Ocean Bottom Seismograph array deployment. We show that the seismicity is distributed along a band aligned with the island chain itself, and is concentrated along several faults with an approximate N150E strike, cutting the Azores plateau in all the area covered by the OBS network. The combination of these new results with other geophysical data permits us to conclude that the tectonic setting of the Azores plateau is characterised by the existence of two sets of faults, in the N120E and N150E directions, defining several crustal blocks, whose relative motion accommodates the interaction of the three megaplates. The deformation of these tectonic blocks is probably driven by the shear between the EU and AF plates. This model explains well the spatial variability of the stress conditions in the Azores domain, the combination of dextral and sinistral strike slip mechanisms and the observed seismotectonics of the Azores islands.  相似文献   

An energy conversion method in the ocean using the density difference of water     

Hitoshi Mochizuki  Wataru Mitsuhashi 《Ocean Engineering》1981,8(1):91-96

A new method which produces energy from the ocean by utilizing the density difference of water, by means of a “chimney effect”, is proposed. Density difference of water in the ocean occurs in two ways, namely differences of consistency and water temperature. For instance, fresh river and melting floes and icebergs are pointed out as some origins of the former, while thermal effects of volcanoes and hot springs may account for the latter. Furthermore, sunlight power transmitted into the sea through glass fibre power lines can be an artificial source in the latter case.This paper concentrates on regions near estuaries where low density river water can be piped into the high density ocean. An analysis estimates that the proposed method extracts energy of several thousands or more kW in the above case.  相似文献   

Sorption behavior of the Pt(II) complex anion on manganese dioxide (δ-MnO2): a model reaction to elucidate the mechanism by which Pt is concentrated into a marine ferromanganese crust     

Mamiko Yamashita Maeno  Hironori Ohashi  Kotaro Yonezu  Akane Miyazaki  Yoshihiro Okaue  Koichiro Watanabe  Tamao Ishida  Makoto Tokunaga  Takushi Yokoyama 《Mineralium Deposita》2016,51(2):211-218

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Spinifex-like textured metaperidotites from the Higo Metamorphic Rocks,Japan, a possible high-pressure dehydration product of antigorite serpentinite     

Tadao Nishiyama  Hibiki Eguchi  Dai Shiosaki  Akira Yoshiasa  Nobutatsu Mochizuki  Yasushi Mori  Kazumasa Sugiyama  Hiroshi Arima  Kunio Yubuta 《Island Arc》2021,30(1):e12382

Spinifex-like textured metaperidotites from the Higo Metamorphic Rocks (HMR), west-central Kyushu, Japan, may be formed by high-pressure dehydration of antigorite, and may indicate deep subduction of serpentinite reaching a pressure–temperature condition of 1.6 GPa and 740–750 °C. Three rock types have been identified based on mineral assemblage and rock texture: Type I (L) consisting of medium-grained (1–5 cm long) olivine + enstatite + chromite ±tremolite with secondary talc and anthophyllite that occurs in low-grade metamorphic rocks of the biotite zone, Type I (H) of coarse-grained (up to 10 cm long) olivine + enstatite (with clinoenstatite lamella) + chromite ±tremolite with secondary talc that occurs in high-grade metamorphic rocks of the garnet-cordierite zone, and Type II composed of Al-spinel + chlorite + olivine + apatite + ilmenite with minor sodic gedrite in the garnet-cordierite zone together with Type I (H). Olivines in all rock types are mostly serpentinized during exhumation. The chromite-olivine thermometer gives 560–690 °C for Type I (L) rocks, and the spinel-olivine thermometer gives 610–740 °C for Type II rocks. The peak metamorphic pressure will be higher than 1.6 GPa based on the location of the experimentally determined invariant point (P = 1.6 GPa and T = 670 °C) of antigorite + forsterite + enstatite + talc + H₂O. This estimate is consistent with the occurrence of chlorite in Type II rocks, which is stable up to 890 °C at 2.0 GPa. The spinifex-like textured metaperidotites occur as small bodies in the low P/T type gneisses, implying tectonic juxtaposition of them probably during exhumation of the HMR. Recent findings of medium pressure (0.9–1.2 GPa) granulites and gneisses from the HMR may indicate that the HMR has a deep root into the wedge mantle from which the spinifex-like textured metaperidotites have derived.  相似文献   

Toroidal oscillations and SH body waves of an aspherical Earth     

E. Mochizuki 《Geophysical Journal International》1992,111(3):497-504

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High-resolution terrestrial carbon isotope and planktic foraminiferal records of the Upper Cenomanian to the Lower Campanian in the Northwest Pacific     

Reishi Takashima  Hiroshi Nishi  Toshiro Yamanaka  Keiichi Hayashi  Amane Waseda  Akiko Obuse  Takashige Tomosugi  Naoki Deguchi  Sunao Mochizuki 《Earth and Planetary Science Letters》2010,289(3-4):570-582

Making Upper Cretaceous biostratigraphic correlations between the Northwest Pacific and Tethyan–Atlantic sections have been difficult because of rare frequencies of age-diagnostic macro- and microfossils in the sequences in the Northwest Pacific region. In order to correlate these sections precisely, an integrated planktic foraminiferal and bulk wood carbon-isotope stratigraphy from the upper Cenomanian to the lower Campanian succession (the middle–upper part of the Yezo Group) of Hokkaido, northern Japan is established with an average resolution of 50 k.y. The δ¹³C curves from bulk wood of the Yezo Group and from bulk carbonate of English Chalk show remarkably similar patterns of isotopic fluctuation, allowing the correlation of 22 carbon isotopic events between these sections. This high-resolution correlation greatly improves the previous micro- and macrofossil biostratigraphic schemes in the Northwest Pacific region, and reveals that global events, such as the oxygen depletion at the OAE 2 horizon, the constant decrease in pCO₂ during the Late Cretaceous, and the eustatic sea-level falls in the late middle Turonian, Santonian/Campanian Boundary and early Campanian, are recorded in the Upper Cretaceous sequence of the Northwest Pacific.  相似文献   

High-resolution observations of the near-infrared emission from NGC 6822 Hubble V     

Sungho Lee  Soojong Pak  Sang-Gak Lee  Christopher J. Davis  Michael J. Kaufman  Kenji Mochizuki  Daniel T. Jaffe 《Monthly notices of the Royal Astronomical Society》2005,361(4):1273-1280

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