Spatial distribution of the apatite fission‐track ages in the Toki granite,central Japan: Exhumation rate of a Cretaceous pluton emplaced in the East Asian continental margin          下载免费PDF全文

Takashi Yuguchi  Shigeru Sueoka  Hideki Iwano  Tohru Danhara  Masayuki Ishibashi  Eiji Sasao  Tadao Nishiyama 《Island Arc》2017,26(6)

The Cretaceous Toki granitic pluton of the Tono district, central Japan was emplaced in the East Asian continental margin at about 70 Ma. The Toki granite has apatite fission‐track (AFT) ages ranging from 52.1 ±2.8 Ma to 37.1 ±3.6 Ma (number of measurements, n = 33); this indicates the three‐dimensional thermal evolution during the pluton's low‐temperature history (temperature in the AFT partial annealing zone: 60–120 °C). The majority of the Toki granite has a spatial distribution of older ages in the shallower parts and younger ages in the deeper parts, representing that the shallower regions arrived (were exhumed) at the AFT closure depth earlier than the deeper regions. Such a cooling pattern was predominantly constrained by the exhumation of the Toki granitic pluton and was related to the regional denudation of the Tono district. The age–elevation relationships (AERs) of the Toki granite indicate a fast exhumation rate of about 0.16 ±0.04 mm/year between 50 Ma and 40 Ma. The AFT inverse calculation using HeFTy program gives time‐temperature paths (t–T paths), suggesting that the pluton experienced continuous slow cooling without massive reheating since about 40 Ma until the present day. A combination of the AERs and AFT inverse calculations represents the following exhumation history of the Toki granite: (i) the fast exhumation at a rate of 0.16 ±0.04 mm/year between 50 Ma and 40 Ma; (ii) slow exhumation at less than 0.16 ±0.04 mm/year after 40 Ma; and (iii) exposure at the surface prior to 30–20 Ma. The Tono district, which contains the Toki granite, underwent slow denudation at a rate of less than 0.16 ±0.04 mm/year within the East Asian continental margin before the Japan Sea opening at 25–15 Ma and then within the Southwest Japan Arc after the Japan Sea opening, which is in good agreement with representative denudation rates obtained in low‐relief hill and plain fields.  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   

CO2-metasomatism of a metabasite block in a serpentine melange from the Nishisonogi metamorphic rocks,southwest Japan     

Tadao Nishiyama 《Contributions to Mineralogy and Petrology》1990,104(1):35-46

Local fluid migration through a serpentine melange caused successive carbonation of a metabasite block (about 80 meter in diameter) during the uplift stage of the glaucophanitic metamorphic rocks, the Nishisonogi metamorphics, southwest Japan. The block shows a zonal sequence as follows. Zone 1: original greenschist (Am+Ep+ Chl+Ab+Sph+Qtz). Zone 2: epidote disappears by the reaction Ep+Am+CO₂+H₂O=Chl+Cc+Qtz. Zone 3: balc appears by the reaction Am+CO₂+H₂O=Ta+Cc+ Qtz. Zone 4:sphene breakdowns by the reaction Sph+ CO₂=Rt+Cc+Qtz. Zone 5: amphibole disappears by the two simultaneous reactions, Am+CO₂=Do+Ta+Qtz and Ta+Cc+CO₂=Do+Qtz+H₂O. Zone 7: albite is replaced by chlorite, calcite, dolomite and quartz, and the assemblage of Do+Cc+Chl+Rt+Qtz is stable. Analyses of phase relations indicate an introduction of CO₂-rich fluid into the greenschist body during regional metamorphism. The CO₂-rich fluid may have formed by devolatilization reactions between serpentinite and graphite-bearing metasediments. The fluid migrated within the melange through a channelized pathway and into the greenschist body from a deeper part of the melange.  相似文献   

Elastic-plastic response spectra for different hysteretic rules     

Tadao Minami  Yutaka Osawa 《地震工程与结构动力学》1988,16(4):555-568

The general features of elastic-plastic response spectra for several accelerograms that are widely used for the design buildings in Japan were studied in terms of the effects of the different hysteretic models used in the analyses. Lare fluctuations existed in the spectra for both input ground motion and the different models. The models were classified according to their strain energy-absorbing capacities in three groups, within each of which the relevant nature of elastic-plastic responses of the structures were similar. Finally, empirical formulae with which to estimate two measures structural damage, the ductility factors and cumulative plastic displacement normalized by the yielding displacement, wer developed for each group of hysteretic models.  相似文献   

Volume transport in the Soya Strait during 2006–2008     

Yasushi Fukamachi  Kay I. Ohshima  Naoto Ebuchi  Tadao Bando  Kazuya Ono  Minoru Sano 《Journal of Oceanography》2010,66(5):685-696

Time-series data of the vertical structure of the Soya Warm Current (SWC) were obtained by a bottom-mounted acoustic Doppler current profiler (ADCP) in the middle of the Soya Strait from September 2006 to July 2008. The site of the ADCP measurement was within the coverage of the ocean-radar measurement around the strait. The volume transport of the SWC through the strait is estimated on the basis of both the vertical structure observed by the ADCP and the horizontal structure observed by the radars for the first time. The annual transport estimates are 0.62–0.67 Sv (1 Sv = 10⁶ m³s⁻¹). They are somewhat smaller than the difference between the previous estimates of the inflow and outflow through other straits in the Sea of Japan, and smaller than those obtained in the region downstream of the strait during 2004–05 (0.94–1.04 Sv). The difference in the two periods may be attributed to interannual variability of the SWC and/or the different measurement locations.  相似文献   

Wave reflection, transmission and harmonics due to different submerged structures     

Gao Xueping  Inouchi Kunimitsu  Kakinuma Tadao 《海洋学报(英文版)》2000,19(2):111-125

I~IOXdifferent tabes of submerged structures restricting wave development are extensively appliedin coastal and barber engineering. Generally speaking, the submerged structures are classified intothree types (see Fig. 1 ): a submerged horizontal plate (fixed submerged structure), a submergedbreakwater (rectangular or trapezoidal) and a step-take structure (toPOgraphy). In order to get aclear understanding of the characteristics of wave motion around submemed structures, manyFig. 1. Fol'InS…  相似文献   

Steady diffusion model for olivine-plagioclase corona growth     

Tadao Nishiyama 《Geochimica et cosmochimica acta》1983,47(2):283-294

This paper describes an application of a steady diffusion model (Joesten, 1977) to an olivineplagioclase corona and some new results about a theoretical background on the steady diffusion equations.The olivine-plagioclase corona in a metanorite from Mt. Ikoma. Japan, has a layer sequence of olivinecummingtonite-hornblende + spinel-plagioclase. An analysis of a set of steady diffusion equations for the corona in the four-component system, MgO-AlO_{$\text{3}\text{2}$}-SiO₂-Na_0.1Ca_0.9O_0.95 (NC) with excess H₂O. successfully gives the exchange cycle (Fisher, 1973) in the layer sequence with specific values of the phenomenological coefficients' ratios; $\text{L}{}_{\mathrm{<mtext>MgMg</mtext>}}\text{L}{}_{\mathrm{<mtext>SiSi</mtext>}}$, $\text{L}{}_{\mathrm{<mtext>MgMg</mtext>}}\text{L}{}_{\mathrm{<mtext>AlAl</mtext>}}$ and $\text{L}{}_{\mathrm{<mtext>MgMg</mtext>}}\text{L}{}_{\mathrm{<mtext>NCNC</mtext>}}$. The factor which controls most strictly the stability of the layer sequence under isobaric-isothermal conditions is $\text{L}{}_{\mathrm{<mtext>MgMg</mtext>}}\text{L}{}_{\mathrm{<mtext>AlAl</mtext>}}$.Theoretical considerations on the steady diffusion equations show that the L-ratios does not depend on concentrations even if the phenomenological coefficients themselves are functions of concentrations. Equivalence of the steady state condition and the minimum rate of entropy production law (Prigogine, 1967) is also proved for the system with fixed chemical potential gradients under isobaric-isothermal conditions, such as reaction bands. These results give a strong background for the model.  相似文献   

On the local equilibrium of winds and wind-waves in relation to surface drag   总被引：3，自引：0，他引：3  

Akira Masuda  Tadao Kusaba 《Journal of Oceanography》1987,43(1):28-36

Local equilibrium of winds and wind-waves is discussed as a basis for research of the drag coefficient of the water surface as well as for the spectral growth of wind-waves. This hypothesis assumes, in a narrow sense, that statistical properties are determined from four physical quantities, which represent winds and wind-waves: the friction velocityu _*, the gravitational accelerationg, the powerE of the surface displacement, and the peak frequency _p of a wind-wave spectrum. Then one has only one nondimensionalcontrol parameter, which may be either the wave age or wave nonlinearity (slope) of dominant waves. In a wide-sense, one can take into account viscosity and surface tension in terms of one more additional parameter by virtue of the virtual invariance of those material constants; that parameter describes the scale ratio between dominant waves and the short waves for which viscosity or surface tension is important. A unified expression for the roughness height according to this hypothesis turns out to include Charnock's and Toba's formulas as special cases. On the basis of a preliminary analysis of the experimental data, a new empirical formula is proposed.  相似文献   

On the relation between the growth rate of water waves and wind speed     

Hisashi Mitsuyasu  Tadao Kusaba 《Journal of Oceanography》1988,44(3):136-142

Various wind velocitiesu _*,U _/2,U andU ₁₀ are correlated to the measured growth rate of water waves , whereu _* is the friction velocity of the wind, andU _/2,U andU ₁₀ are the wind speeds respectively at the heights /2, and 10m above sea surface (: wave length). It is shown that within a range of the dimensionless wind speed, 0.1<u _* /C<0.6, there are no appreciable differences in the correlations, whereC is the phase velocity of water waves. The present relation between andU shows qualitatively similar properties as the one obtained by Al'Zanaidi and Hui (1984); the growth rate for waves with rough surface is larger than that with smooth surface. However, our present relations give, for the both waves with different surface roughness, larger values by factors 1.71.8 than those given by Al'Zanaidi and Hui's relation.  相似文献   

Cooling process of a granitic body deduced from the extents of exsolution and deuteric sub-solidus reactions: Case study of the Okueyama granitic body, Kyushu, Japan     

Takashi Yuguchi  Tadao Nishiyama 《Lithos》2007,97(3-4):395-421

The variation in cooling processes with depth in a magma body is evaluated quantitatively by analysis of the extent of exsolution coarsening and deuteric coarsening as sub-solidus reactions. This method is applied to evaluation of the Okueyama granitic body of central Kyushu, Japan. Exsolution coarsening has produced microperthite textures in this body, while deuteric coarsening has resulted in patchperthite, myrmekite, and reaction rims, respectively. Through measurement of six textural parameters, including the width and spacing of lamellae and the thickness of myrmekite and reaction rims, the extent of these sub-solidus reactions is shown to increase systematically with depth in the granite body, indicating that the Okueyama cooled gradually from the roof. The hornblende–plagioclase and ternary feldspar thermometers indicate temperature a range of 710 to 620 °C for volume diffusion associated with exsolution coarsening, while deuteric coarsening is found to have occurred at temperatures below 500 °C on the basis of the ternary feldspar thermometer. The cooling period corresponding to exsolution coarsening is estimated using a one-dimensional heat transfer model, yielding periods of 820 y at the roof and 1390–1890 y at the base of the exposure (1000 m below the roof) depending on total depth of the original magma body.  相似文献