Phase transition of zircon at high P-T conditions     

Shigeaki?OnoEmail author  Kenichi?Funakoshi  Yoichi?Nakajima  Yoshinori?Tange  Tomoo?Katsura 《Contributions to Mineralogy and Petrology》2004,147(4):505-509

Abstract In situ observations of the zircon-reidite transition in ZrSiO₄ were carried out using a multianvil high-pressure apparatus and synchrotron radiation. The phase boundary between zircon and reidite was determined to be P (GPa) = 8.5+0.0017×(T-1200) (K) for temperatures between 1100–1900 K. When subducted slabs, including igneous rocks and sediments, descend into the upper mantle, the zircon in the subducted slab transforms into reidite at pressures of about 9 GPa, corresponding to a depth of 270 km. Reidite found in an upper Eocene impact ejecta layer in marine sediments is thought to have been transformed from zircon by a shock event. The peak pressure generated by the shock event in this occurrence is estimated to be higher than 8 GPa.Editorial responsibility: J. Hoefs  相似文献   

Statistical discrimination of foreshocks from other earthquake clusters   总被引：1，自引：0，他引：1  

Yosihiko Ogata  Tokuji Utsu  Koichi Katsura 《Geophysical Journal International》1996,127(1):17-30

When earthquake activity begins, it may be a foreshock sequence to a larger earthquake, a swarm, or a simple main-shock-aftershock sequence. This paper is concerned with the conditional probability that it will be foreshock activity of a later larger earthquake, depending on the occurrence pattern of some early events in the sequence. The earthquake catalogue of the Japan Meteorological Agency (1926-1993, M_J≥4) is decomposed into a large number of clusters in time and space in order to compare statistical features of foreshocks with those of swarms and aftershocks. Using such a data set, Ogata, Utsu & Katsura (1995) revealed some discriminating features of foreshocks relative to the other types of clusters, for example the events' closer proximity in time and space, and a tendency towards chronologically increasing magnitudes, which encouraged us to construct models which forecast the probability of the earthquakes being foreshocks. Specifically, the probability is a function of the history of magnitude differences, spans between origin times and distances between epicentres within a cluster. For purposes of illustration, the models were fitted to the early part of the data (1926-1975) and the validity of the forecasting procedure was checked on data from the later period (1976-1993). Two procedures for evaluating the performance of the probability forecast are suggested. Furthermore, for the case where only a single event is available (i.e. either it is the first event in a cluster or an isolated event), we also forecast the probability of the event being a foreshock as a function of its geographic location. Then, the validity of the forecast is demonstrated in a similar manner. Finally, making use of the multi-element prediction formula, we show that the forecasting performance is enhanced by the joint use of the information in the location of the first event, and that in the subsequent interevent history in the cluster.  相似文献   

Aluminum substitution mechanisms in perovskite-type MgSiO<Subscript>3</Subscript>: an investigation by Rietveld analysis     

Hiroshi Kojitani  Tomoo Katsura  Masaki Akaogi 《Physics and Chemistry of Minerals》2007,34(4):257-267

Al-containing MgSiO₃ perovskites of four different compositions were synthesized at 27 GPa and 1,873 K using a Kawai-type high-pressure apparatus: stoichiometric compositions of Mg_0.975Si_0.975Al_0.05O₃ and Mg_0.95Si_0.95Al_0.10O₃ considering only coupled substitution Mg²⁺ + Si⁴⁺ = 2Al³⁺, and nonstoichiometric compositions of Mg_0.99Si_0.96Al_0.05O_2.985 and Mg_0.97Si_0.93Al_0.10O_2.98 taking account of not only the coupled substitution but also oxygen vacancy substitution 2Si⁴⁺ = 2Al³⁺ + V_O¨. Using the X-ray diffraction profiles, Rietveld analyses were performed, and the results were compared between the stoichiometric and nonstoichiometric perovskites. Lattice parameter–composition relations, in space group Pbnm, were obtained as follows. The a parameters of both of the stoichiometric and nonstoichiometric perovskites are almost constant in the X _Al range of 0–0.05, where X _Al is Al number on the basis of total cation of two (X _Al = 2Al/(Mg + Si + Al)), and decrease with further increasing X _Al. The b and c parameters of the stoichiometric perovskites increase linearly with increasing Al content. The change in the b parameter of the nonstoichiometric perovskites with Al content is the same as that of the stoichiometric perovskites within the uncertainties. The c parameter of the nonstoichiometric perovskites is slightly smaller than that of the stoichiometric perovskites at X _Al of 0.10, though they are the same as each other at X _Al of 0.05. The Si(Al)–O1 distance, Si(Al)–O1–Si(Al) angle and minimum Mg(Al)–O distance of the nonstoichiometric perovskites keep almost constant up to X _Al of 0.05, and then the Si(Al)–O1 increases and both of the Si(Al)–O1–Si(Al) angle and minimum Mg(Al)–O decrease with further Al substitution. These results suggest that the oxygen vacancy substitution may be superior to the coupled substitution up to X _Al of about 0.05 and that more Al could be substituted only by the coupled substitution at 27 GPa. The Si(Al)–O1 distance and one of two independent Si(Al)–O2 distances in Si(Al)O₆ octahedra in the nonstoichiometric perovskites are always shorter than those in the stoichiometric perovskite at the same Al content. These results imply that oxygen defects may exist in the nonstoichiometric perovskites and distribute randomly.  相似文献   

Differentation of magmatic emanation     

I. Iwasaki  T. Ozawa  M. Yoshida  T. Katsura  B. Iwasaki  M. Kamada 《Bulletin of Volcanology》1964,27(1):79-80

Chemical properties of magmatic emanation can be estimated roughly by i) volatiles from rocks by heating at various temperatures, ii) volcanic emanations, iii) residual magmatic emanations, iv) calculation from chemical equilibrium between volatile matters and magmas. Magmatic emanation is assumed to consist all of the volatile matters in magmas such asH ₂ O, HCl, HF, SO ₂ H ₂ S, H ₂,CO 2,N ₂ and others (halides, etc.) at about 1200°C, although various kinds of magmatic emanations can be formed at different conditions. Magmatic emanation separated from magmas will change their chemical properties by many factors such as changes of temperature and pressure (displacement of chemical equilibrium), and reactions with other substances and it will differentiate into volcanic gases, volcanic waters, volcanic sublimates, and hydrothermal deposits (hot spring deposits). At temperatures above the critical point of water, separation of solid phase (sublimates), liquid phase, and displacement of chemical equilibrium may take place, and gaseous phase will gradually change their chemical properties as will be seen at many fumaroles. Chloride, hydrogen, andSO ₂ contents will gradually decrease along with lowering temperature. Once aqueous liquid phase appears below the critical point of water, all the soluble materials may dissolve into this hydrothermal solution. Consequently, the gaseous phase at this stage must have usually a little hydrogen chloride as is observed at many fumaroles. Aqueous solutions must be of acidic nature by dissolution of acid forming components, and by hydrolysis (Chloride type). When a self-reduction-oxidation reaction of sulfurous acid takes place, an aqueous solution of sulfate type will be formed. At this stage, solid phases consist of the remained sublimates which are difficultly soluble in aqueous solution, and deposits formed by reaction in the hydrothermal solutions. The gaseous phases below the boiling point of water, have usually a little water, and consist mainly ofCO ₂ type,H ₂ S type,N ₂ type, and mixed type owing to elimination or addition of components by reactions with waters or wall rocks according to their geological conditions. Aqueous solutions which was of acidic nature must be changed into alkaline solutions by reaction with wall rocks for a long time. When the oxidation of sulfur compounds takes place, an aqueous solution of sulfate type will be formed. Hydrogen sulfide type of water will be formed by reaction of sulfides with acid waters or absorption of hydrogen sulfide. Carbonate type of water will be formed whenCO ₂ is absorbed. Solid phases at this stage consist usually of hydrothermal deposits except for that at solfatara or mofette. The course of differentiation of magmatic emanation could take place in more complicated ways than that of magmatic differentiation.  相似文献   

Experiment and validation of numerical simulation of coupled thermal,hydraulic and mechanical behaviour in the engineered buffer materials     

Masakazu Chijimatsu  Tomoo Fujita  Akira Kobayashi  Masashi Nakano 《国际地质力学数值与分析法杂志》2000,24(4):403-424

Evaluation of the coupled heat transfer, water flow and stress changes in the engineered clay barrier is an important issue in the performance assessment of the high‐level radioactive waste disposal. To demonstrate the function of the engineered barrier system, the large‐scale experiment is conducted, which is called Big Bentonite facility (BIG‐BEN). The facility consists of an electric heater surrounded by glass beads, carbon steel overpack, buffer material and man‐made rock. The buffer is a mixture of bentonite and sand. The heater is operated at 0·8 kW. Water is injected from the interface between the buffer and the man‐made rocks at the pressure of 0·05 MPa. The duration of the experiment is 20 months. The change in temperature and swelling pressure are continuously monitored and gravimetric water content is measured by sampling. The coupled thermal, hydraulic and mechanical processes are simulated with a finite element code THAMES, which can simulate the fully coupled phenomena in the saturated and unsaturated clay under anisothermal condition. To examine the validity of the code, all the parameters used in the model are evaluated from the other laboratory tests. The simulated results are compared with the measured ones without calibration of the parameter values using the results from the BIG‐BEN experiment. It can be concluded that the changes in temperature and gravimetric water content within the buffer can be simulated reasonably well and that the mechanical effect such as swelling pressure is difficult to realize. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

Production of the Blood Pressure Lowing Peptides from Brown Alga ( Undaria pinnatifida )     

Sato Minoru  Oba Takashi  Hosokawa Takao  Yamaguchi Toshiyasu  Nakano Toshiki  Saito Tadao  Muramoto Koji  Kahara Takashi  Funayama Katsura  Kobayashi Akio  Nakano Takahisa 《中国海洋大学学报(英文版)》2005,4(3)

1 IntroductionIncreased blood pressure appears to be one of theprimary risk factors of circulatory organ diseases suchas encepharo-apoplexy, encepharo-infarction and cardi-ac infraction. Angiotensin-I-converting enzyme (ACE)plays an important role in the rennin-angiotensin sys-tem by regulating blood pressure. Antihypertensivedrugs such as captopril and enalapril are potent ACEinhibitors (Ondetti et al., 1977). Recently, severalinhibitory peptides derived from food proteins havebeen isolat…  相似文献   

Degassing, crystallization and eruption dynamics at Stromboli: trace element and lithium isotopic evidence from 2003 ashes     

Federica Schiavi  Katsura Kobayashi  Takuya Moriguti  Eizo Nakamura  Massimo Pompilio  Massimo Tiepolo  Riccardo Vannucci 《Contributions to Mineralogy and Petrology》2010,159(4):541-561

During its 1800-year-long persistent activity the Stromboli volcano has erupted a highly porphyritic (HP) volatile-poor scoriaceous magma and a low porphyritic (LP) volatile-rich pumiceous magma. The HP magma is erupted during normal Strombolian explosions and lava effusions, while the LP one is related to more energetic paroxysms. During the March–April 2003 explosive activity, Stromboli ejected two typologies of juvenile glassy ashes, namely highly vesicular LP shards and volatile-poor HP shards. Their textural and in situ chemical characteristics are used to unravel mutual relationships between HP and LP magmas, as well as magma dynamics within the shallow plumbing system. The mantle-normalized trace element patterns of both ash types show the typical arc-lava pattern; however, HP glasses possess incompatible element concentrations higher than LP glasses, along with Sr and Eu negative anomalies. HP shards are generally characterized by higher Li contents (to ~20 ppm) and lower δ⁷Li values (+1.2 to −3.8‰) with respect to LP shards (Li contents of 7–14 ppm and δ⁷Li ranging between +4.6 and +0.9‰). Fractional crystallization models based on major and trace element compositions, combined with a degassing model based on open-system Rayleigh distillation and on the assumption that ^melt/fluidD_Li > 1, show that abundant (~30%) plagioclase precipitation and variable degrees of degassing can lead the more primitive LP magma to evolve toward a differentiated (isotopically lighter) HP magma ponding in the upper conduit and undergoing slow continuous degassing-induced crystallization. This study also evidences that in March 2003 Stromboli volcano poured out a small early volume of LP magma that traveled slower within the conduit with respect to later and larger volumes of fast ascending LP magma erupted during the April 5 paroxysm. The different ascent rates and cooling rates of the two LP magma batches (i.e., pre- and post-paroxysm) resulted in small, but detectable, differences in their chemical signatures. Finally, this study highlights the high potential of in situ investigations of juvenile glassy ashes in petrologic and geochemical monitoring the volcanic activity and of Li isotopes as tracers of degassing processes within the shallow plumbing system.  相似文献   

Temperature scaling pattern dependence on representative concentration pathway emission scenarios
A letter     

Yasuhiro Ishizaki  Hideo Shiogama  Seita Emori  Tokuta Yokohata  Toru Nozawa  Tomoo Ogura  Manabu Abe  Masakazu Yoshimori  Kiyoshi Takahashi 《Climatic change》2012,112(2):535-546

To preserve consistency among developed emission scenarios, the scenarios used in climate modeling, and the climate scenarios available for impact research, the pattern scaling technique is useful technique. The basic assumption of pattern scaling is that the spatial response pattern per 1 K increase in the global mean surface air temperature (SAT) (scaling pattern) is the same among emission scenarios, but this assumption requires further validation. We therefore investigated the dependence of the scaling pattern of the annual mean SAT on GHGs emission scenarios of representative concentration pathways (RCP) and the causes of that dependence using the Model for Interdisciplinary research on Climate 5 developed by Japanese research community. In particular, we focused on the relationships of the dependency with effects of aerosols and Atlantic meridional overturning circulation. We found significant dependencies of the scaling pattern on emission scenarios at middle and high latitudes of the Northern Hemisphere, with differences of >15 % over parts of East Asia, North America, and Europe. Impact researchers should take into account those dependencies that seriously affect their research. The mid-latitude dependence is caused by differences in sulfate aerosol emissions per 1 K increase in the global mean SAT, and the high-latitude dependence is mainly caused by nonlinear responses of sea ice and ocean heat transport to global warming. Long-term trends in land-use and land-cover changes did not significantly affect the scaling pattern of annual mean SAT, but they might have an effect at different timescales.  相似文献   

The effect of oxygen fugacity on ionic conductivity in olivine     

Hongzhan Fei  Tomoo Katsura 《地学前缘(英文版)》2022,(1):76-84

The oxygen fugacity(f_O2) may affect the ionic conductivity of olivine under upper mantle conditions because Mg vacancies can be produced in the crystal structure by the oxidization of iron from Fe²⁺ to Fe3+. Here we investigated olivine ionic conductivity at 4 GPa, as a function of temperature, crystallographic orientation, and oxygen fugacity, corresponding to the topmost asthenospheric conditions. The results demonstrate that the ionic conductivity is insensitive to f_O2 under relatively reduced conditions(f_O2 below Re-ReO₂ buffer), whereas it has a clear f_O2-dependence under relatively oxidized conditions(f_O2 around the magnetite-hematite buffer). The ionic conduction in olivine may contribute significantly to the conductivity anomaly in the topmost asthenosphere especially at relatively oxidized conditions.  相似文献   

Emission scenario dependencies in climate change assessments of the hydrological cycle   总被引：1，自引：1，他引：0  

Hideo Shiogama  Naota Hanasaki  Yuji Masutomi  Tatsuya Nagashima  Tomoo Ogura  Kiyoshi Takahashi  Yasuaki Hijioka  Toshihiko Takemura  Toru Nozawa  Seita Emori 《Climatic change》2010,99(1-2):321-329

Anthropogenic global warming will lead to changes in the global hydrological cycle. The uncertainty in precipitation sensitivity per 1 K of global warming across coupled atmosphere-ocean general circulation models (AOGCMs) has been actively examined. On the other hand, the uncertainty in precipitation sensitivity in different emission scenarios of greenhouse gases (GHGs) and aerosols has received little attention. Here we show a robust emission-scenario dependency (ESD); smaller global precipitation sensitivities occur in higher GHG and aerosol emission scenarios. Although previous studies have applied this ESD to the multi-AOGCM mean, our surprising finding is that current AOGCMs all have the common ESD in the same direction. Different aerosol emissions lead to this ESD. The implications of the ESD of precipitation sensitivity extend far beyond climate analyses. As we show, the ESD potentially propagates into considerable biases in impact assessments of the hydrological cycle via a widely used technique, so-called pattern scaling. Since pattern scaling is essential to conducting parallel analyses across climate, impact, adaptation and mitigation scenarios in the next report from the Intergovernmental Panel on Climate Change, more attention should be paid to the ESD of precipitation sensitivity.  相似文献