Newly-generated Daliangshan Fault Zone—Shortcutting on the central section of Xianshuihe-Xiaojiang fault system   总被引：3，自引：0，他引：3  

HongLin He  Yasutaka Ikeda  YuLin He  Masayoshi Togo  Jie Chen  ChangYun Chen  Masayoshi Tajikara  Tomoo Echigo  Shinsuke Okada 《中国科学D辑(英文版)》2008,51(9):1248-1258

The Daliangshan fault zone is the eastern branch in the central section of Xianshuihe-Xiaojiang fault system. It has been neglected for a long time, partly because of no destructive earthquake records along this fault zone. On the other hand, it is located on the remote and inaccessible plateau. So far it was excluded as part of the Xianshuihe-Xiaojiang fault system. Based on the interpretation of aerophotographs and field investigations, we document this fault zone in detail, and give an estimation of strike-slip rate about 3 mm/a in Late Quaternary together with age dating data. The results suggest that the Daliangshan fault zone is a newly-generated fault zone resulted from shortcutting in the central section of Xianshuihe-Xiaojiang fault system because of the clockwise rotation of the Southeastern Tibetan Crustal Block, which is bounded by the Xianshuihe-Xiaojiang fault system. Moreover, the shortcutting may make the Daliangshan fault zone replace the Anninghe and Zemuhe fault zones gradually, and finally, the later two fault zones will probably die out with the continuous clockwise rotation.  相似文献   

Possible magma intrusion revealed by temporal gravity, ground deformation and ground temperature observations at Mount Komagatake (Hokkaido) during the 1996–1998 crisis     

Philippe Jousset  Hitoshi Mori  Hiromu Okada 《Geophysical Journal International》2000,143(3):557-574

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Cretaceous tectonic events in the border regions between the Asian continent and the proto-Pacific     

Hakuyu Okada and  Takashi Sakai 《Island Arc》1999,8(3):335-335

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On the atmospheric muon energy spectrum in the deep ocean and its parameterization     

Atsushi Okada 《Astroparticle Physics》1994,2(4):393-400

The energy spectrum of those muons in the deep ocean ( 1000 m) that have been produced in the terrestrial atmosphere and have penetrated sea-water is calculated by Monte Carlo simulation and presented in a simplified form for easy use.  相似文献   

New Rapid Evaluation for Long-Term Behavior in Deep Geological Repository by Geotechnical Centrifuge. Part 1: Test of Physical Modeling in Near Field Under Isotropic Stress-Constraint Conditions     

Soshi Nishimoto  Masataka Sawada  Tetsuji Okada 《Rock Mechanics and Rock Engineering》2016,49(8):3323-3341

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Study on the managanese nodule     

Akihiko Okada  Makoto Shima 《Journal of Oceanography》1970,26(3):151-158

Chemical and X-ray analyses were performed on the fifteen manganese nodules collected from the Pacific Ocean floor. The results were discussed compared with the previous data on the manganese nodules. Minerals were found to be todorokite, δ-MnO₂ and other silicates, montmorillonite, illite, phillipsite and α-SiO₂. Average composition shows that copper is concentrated on the deep sea nodules more than the shallow ones, and that the todorokite rich nodules contain more copper and nickel than the δ-MnO₂ rich ones. The analyses of fresh water iron-manganese precipitates by bacterial activity suggest that biological process is one of the important factors on the genesis of the sedimentary iron-manganese deposits, including the manganese nodule. The Institute of Physical and Chemical Research  相似文献   

Simultaneous Measurement of Hydrogen Peroxide and Fe Species (Fe(II) and Fe<Subscript>(tot)</Subscript>) in Okinawa Island Seawater: Impacts of Red Soil Pollution     

Takemitsu?ArakakiEmail author  Hiroyuki?Fujimura  Asha?Mansour?Hamdun  Kouichirou?Okada  Hiroaki?Kondo  Tamotsu?Oomori  Akira?Tanahara  Hatsuo?Taira 《Journal of Oceanography》2005,61(3):561-568

The northern part of Okinawa Island suffers from red soil pollution—runoff of red soil into coastal seawater—which damages coastal ecosystems and scenery. To elucidate the impacts of red soil pollution on the oxidizing power of seawater, hydrogen peroxide (HOOH) and iron species including Fe(II) and total iron (Fe_(tot), defined as the sum of Fe(II) and Fe(III)) were measured simultaneously in seawater from Taira Bay (red-soil-polluted sea) and Sesoko Island (unpolluted sea), off the northern part of Okinawa Island, Japan. We performed simultaneous measurements of HOOH and Fe(II) because the reaction between HOOH and Fe(II) forms hydroxyl radical (•OH), the most potent environmental oxidant. Gas-phase HOOH concentrations were also measured to better understand the sources of HOOH in seawater. Both HOOH and Fe(II) in seawater showed a clear diurnal variation, i.e. higher in the daytime and lower at night, while Fe_(tot) concentrations were relatively constant throughout the sampling period. Fe(II) and Fe_(tot) concentrations were approximately 58% and 19% higher in red-soil-polluted seawater than in unpolluted seawater. Gas-phase HOOH and seawater HOOH concentrations were comparable at both sampling sites, ranging from 1.4 to 5.4 ppbv in air and 30 to 160 nM in seawater. Since Fe(II) concentrations were higher in red-soil-polluted seawater while concentrations of HOOH were similar, •OH would form faster in red-soil-polluted seawater than in unpolluted seawater. Since the major scavenger of •OH, Br⁻, is expected to have similar concentrations at both sites, red-soil-polluted seawater is expected to have higher steady-state •OH concentrations.  相似文献   

Diatom Assemblage and Productivity Changes during the Last 340,000 Years in the Subarctic Pacific     

Kota Katsuki  Kozo Takahashi  Makoto Okada 《Journal of Oceanography》2003,59(5):695-707

Diatoms represent the major part of the microfossils preserved in the subarctic Pacific sediments. During the warm climate intervals the diatom accumulation rate (DAR) tended to increase, whereas it tended to decrease during the cold intervals. Principal component (PC) analysis of the fossil diatom assemblages in Piston Core KH99-3 ES samples from the subarctic Pacific was carried out to investigate the paleoceanographic conditions of the area. PC1 (59.9% of the total variance) was represented by Neodenticula seminae, a characteristic species representing the high nutrient concentrations, which dominated during the interglacial periods. The DAR and PC changes can be attributed to a global origin that is influenced by the nutrient change due to intermediate water change and to a local one that is explained by the change of upwelling region. The analysis of PC2 (17.1% of the total variance) indicates the change of water mass in the western subarctic Pacific. During Marine Isotope Stages (MIS) 2 and 3, the western subarctic Pacific region was significantly influenced by the sea-ice, which may have been derived from the coastal region or a proximal marginal sea. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Chemical and mineralogical compositions of two grains recovered from asteroid Itokawa          下载免费PDF全文

M. Ebihara  N. Shirai  S. Sekimoto  T. Nakamura  A. Tsuchiyama  J. Matsuno  T. Matsumoto  M. Tanaka  M. Abe  A. Fujimura  Y. Ishibashi  Y. Karouji  T. Mukai  T. Okada  M. Uesugi  T. Yada 《Meteoritics & planetary science》2015,50(2):243-254

Two silicate grains (RB‐QD04‐0049 and RA‐QD02‐0064, whose estimated masses are 0.050 μg and 0.048 μg, respectively) recovered from the asteroid Itokawa by the Hayabusa spacecraft were studied for their mineralogical characteristics by synchrotron X‐ray diffraction and synchrotron X‐ray microtomography and further analyzed for their bulk chemical compositions by instrumental neutron activation analysis (INAA). According to X‐ray tomography, RB‐QD004‐0049 is composed of olivine, high‐Ca pyroxene, plagioclase, Ca‐phosphate, and troilite, whereas RA‐QD002‐0064 entirely consists of olivine. INAA data are consistent with these mineral compositions except for rare earth elements (REEs). Although the grain RB‐QD004‐0049 contains measurable REEs, which seems to be consistent with the presence of Ca‐phosphate, their abundances are anomalously high. Very low abundance of Co implies less than 0.1 mass% of metals in these two grains by calculation, which is in contrast to the result for the previously analyzed grain RA‐QD02‐0049 (Ebihara et al., 2011). FeO/Sc ratios of the grains fall within the range of those for ordinary chondrite olivines, implying that these grains are extraterrestrial in origin. FeO/MnO ratios also confirm this conclusion and further suggest that the Hayabusa grains analyzed in this study are similar to material found in LL chondrites rather than CK chondrites although olivines from LL and CK chondrites have similar Fa# (molar% of Fe relative to [Fe+Mg] in olivine) (~30) to those of the Hayabusa grains including the two grains analyzed in this study.  相似文献   

40Ar/39Ar age of material returned from asteroid 25143 Itokawa          下载免费PDF全文

Jisun Park  Brent D. Turrin  Gregory F. Herzog  Fara N. Lindsay  Jeremy S. Delaney  Carl C. Swisher III  Masayuki Uesugi  Yuzuru Karouji  Toru Yada  Masanao Abe  Tatsuaki Okada  Yukihiro Ishibashi 《Meteoritics & planetary science》2015,50(12):2087-2098

The Hayabusa mission to asteroid 25143, Itokawa, brought back 2000 small particles, which most closely resemble material found in LL4‐6 chondrites. We report an ⁴⁰Ar/³⁹Ar age of 1.3 ± 0.3 Ga for a sample of Itokawa consisting of three grains with a total mass of ~2 μg. This age is lower than the >4.0 Ga ages measured for 75% of LL chondrites but close to one for Y‐790964 and its pairs. The flat ⁴⁰Ar/³⁹Ar release spectrum of the sample suggests complete degassing 1.3 Ga ago. Recent solar heating in Itokawa's current orbit does not appear likely to have reset that age. Solar or impact heating 1.3 Ga ago could have done so. If impact heating was responsible, then the 1.3 Ga age sets an upper bound on the time at which the Itokawa rubble pile was assembled and suggests that rubble pile creation was an ongoing process in the inner solar system for at least the first 3 billion years of solar system history.  相似文献