Degassing of deep-sourced CO2 from Xianshuihe-Anninghe fault zones in the eastern Tibetan Plateau     

Sheng XU  Lufeng GUAN  Maoliang ZHANG  Jun ZHONG  Wei LIU  Xian'gang XIE  Congqiang LIU  Naoto TAKAHATA  Yuji SANO 《中国科学:地球科学(英文版)》2022,65(1):139-155

A large number of gases are releasing from the medium-high temperature geothermal fields distributed along the large-scale strike-slip fault zones in the southeastern margin of the Tibetan Plateau.In this study,11 hot spring water and the associated bubbling gas samples were collected along the Xianshuihe-Anninghe fault zones(XSH-ANHFZ)and analyzed for chemical and isotopic compositions.The δ¹⁸_{H_(2}O) and δD_{H_(2}O) values indicate that hot spring waters are predominantly meteoric origin recharged from different altitudes.Most water samples are significantly enriched in Na⁺ and HCO₃ due to the dissolution of regional evaporites,carbonates and Na-silicates.³He/⁴He ratios of the gas samples are 0.025-2.73 times the atmospheric value.The ³He/⁴He ratios are high in the Kangding region where the dense faults are distributed,and gradually decrease with increasing distance from Kangding towards both sides along the Xianshuihe fault zones(XSHFZ).Hydrothermal fluids have dissolved inorganic carbon(DIC)concentrations from 2 to 42 mmol L^-1,δ¹³C_DIC from -6.9‰ to 1.3‰,δ¹³C_{CO_(2}) from -7.2‰ to -3.6‰ and Δ¹⁴C from -997‰ to -909‰.Combining regional geochemical and geological information,the CO₂sources can be attributed to deep-sourced CO₂from mantle and metamorphism of marine carbonate,and shallow-sourced CO₂from the dissolution of marine carbonate and biogenic CO₂.The mass balance model shows that 11±6% of the DIC is sourced from the dissolution of shallow carbonate minerals,9±8% formed by pyrolysis of sedimentary organic matter,80±9% derived from deep metamorphic origin and mantle-derived CO₂.Among them,the deep-sourced CO₂in Anninghe fault zones(ANHFZ)is merely metamorphic carbon,whereas ca.12% and ca.88% of the deep-sourced CO₂in the XSHFZ are derived from the mantle and metamorphic carbon,respectively.The average deep-sourced CO₂flux in the Kangding geothermal field is estimated to be 160 ta^-1.If all the hot springs in various fault zones in the southeastern margin of the Tibetan Plateau are taken into account,the regional deep-sourced CO₂flux would reach ca.10⁵ ta^-1.These results show that the deep-sourced CO₂released from nonvolcanic areas might account for a considerable proportion of the total amount of global deep-sourced carbon degassing,which should be paid more attention to.  相似文献   

Japanese Ocean Flux Data Sets with Use of Remote Sensing Observations (J-OFURO)   总被引：1，自引：1，他引：1  

Masahisa Kubota  Naoto Iwasaka  Shoichi Kizu  Masanori Konda  Kunio Kutsuwada 《Journal of Oceanography》2002,58(1):213-225

We have constructed ocean surface data sets using mainly satellite data and called them Japanese Ocean Flux data sets with Use of Remote sensing Observations (J-OFURO). The data sets include shortwave radiation, longwave radiation, latent heat flux, sensible heat flux, and momentum flux etc. This article introduces J-OFURO and compares it with other global flux data sets such as European Centre for Medium Range Weather Forecasting (ECMWF) and National Center for Environmental Prediction (NCEP) reanalysis data and da Silva et al. (1994). The usual ECMWF data are used for comparison of zonal wind. The comparison is carried out for a meridional profile along the dateline for January and July 1993. Although the overall spatial variation is common for all the products, there is a large difference between them in places. J-OFURO shortwave radiation in July shows larger meridional contrast than other data sets. On the other hand, J-OFURO underestimates longwave radiation flux at low- and mid-latitudes in the Southern Hemisphere. J-OFURO latent heat flux in January overestimates at 10°N–20°N and underestimates at 25°N–40°N. Finally, J-OFURO shows a larger oceanic net heat loss at 10°N–20°N and a smaller loss north of 20°N in January. The data of da Silva et al. in July show small net heat loss around 20°S and large gain around 20°N, while the NCEP reanalysis (NRA) data show the opposite. The da Silva et al. zonal wind speed overestimates at low-latitudes in January, while ECMWF wind data seem to underestimate the easterlies. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Probability Distribution of Surface Wave Slope Derived Using Sun Glitter Images from Geostationary Meteorological Satellite and Surface Vector Winds from Scatterometers     

Naoto Ebuchi  Shoichi Kizu 《Journal of Oceanography》2002,58(3):477-486

The probability distribution of the sea surface slope has been estimated using sun glitter images derived from the visible wavelength radiometer on the Geostationary Meteorological Satellite (GMS) and surface vector winds observed by spaceborne scatterometers. The brightness of the visible images is converted to the probability of wave surfaces which reflect the sunlight toward GMS in grids of 0.25° × 0.25° (latitude × longitude). The slope and azimuth angle required for the reflection of the sun's rays toward GMS are calculated for each grid from the geometry of GMS observation and location of the sun. The GMS images are then collocated with surface wind data observed by three scatterometers. Using the collocated data set of about 30 million points obtained in a period of 4 years from 1995 to 1999, the probability distribution function of the surface slope is estimated as a function of wind speed and azimuth angle relative to the wind direction. The results are compared with those of Cox and Munk (1954a). The surface slope estimated by the present method shows a narrower distribution and much less directivity relative to the wind direction than that reported by Cox and Munk. It is expected that their data were obtained under conditions of growing wind waves. In general, wind waves are not always developing, and the slope distribution might differ from the results of Cox and Munk. Most of our data are obtained in the subtropical seas under clear-sky conditions. This difference in the conditions may be the reason for the difference of slope distribution. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Methane in the western North Pacific   总被引：7，自引：0，他引：7  

Shuich Watanabe  Naoto Higashitani  Nobuo Tsurushima  Shizuo Tsunogai 《Journal of Oceanography》1995,51(1):39-60

The concentration of methane in about 400 seawater samples collected in the western North Pacific, mostly from 40°N to 5°S along 165°E was determined. While the concentration of methane in the surface water was slightly greater in the high-latitudes, it did not widely vary with a standard deviation of 0.29 n mol/l for a mean value of 2.49 n mol/l. The 90% confidence limit of the mean was 0.08 n mol/l. The degree of oversaturation in 1991 (31±4%) was not different from that in circa 1970. If we assume that this degree of oversaturation occurs in the entire oceans, the annual flux of methane becomes 6×10¹²g CH₄. Both the concentrations of methane and chlorophylla were higher in the surface 100 m layer. However, the correlation between them was not well in the entire surface waters. This may indicate that the production of methane is not directly related to the photosynthetic process. The concentration of methane decreased gradually with increasing depth down to 1000 m. Its horizontally and vertically uniform concentration in the abyssal water suggests that the turnover time of methane in the oxic pelagic water is in the range between a few years and a few hundred years.  相似文献   

Validation of wind speeds and significant wave heights observed by the TOPEX altimeter around Japan   总被引：5，自引：0，他引：5  

Naoto Ebuchi  Hiroshi Kawamura 《Journal of Oceanography》1994,50(4):479-487

The wind speeds and significant wave heights observed by the TOPEX altimeter during the first 30 repeat cycles (for about 10 months) are validated by comparing with the data obtained at Japanese Ocean Data Buoy stations. The values of Kuband ⁰ observed by the altimeter show good agreement with those estimated from the buoy wind speed using the modified Chelton-Wentz algorithm. The wind speeds derived from the Ku-band ⁰ using the algorithm agree well with the buoy data with an rms difference of 1.99 ms^–1. The significant wave heights observed by the altimeter have a systematic bias of 0.3 m.  相似文献   

Pre-Japan-ARGO: Experimental Observation of Upper and Middle Layers South of the Kuroshio Extension Region Using Profiling Floats     

Naoto Iwasaka  Toshio Suga  Kensuke Takeuchi  Keisuke Mizuno  Yasushi Takatsuki  Kentaro Ando  Taiyo Kobayashi  Eitarou Oka  Yasuko Ichikawa  Motoki Miyazaki  Hiroshi Matsuura  Kenji Izawa  Chan-Su Yang  Nobuyuki Shikama  Momoko Aoshima 《Journal of Oceanography》2003,59(1):119-127

We deployed two profiling floats in the region south of the Kuroshio Extension in March 2000. Temperature and salinity profiles from a depth of 1500 × 10⁴ Pa to the surface are reported every two and four weeks, respectively. The floats performed very well for first four months after deployment. Later they failed in surfacing for a few months when the sea surface temperature in the region was high. The salinity sensors seemed to suffer from some damage during their failure-in-surfacing period. Despite this trouble, the results clearly demonstrate that the profiling float is a very useful and cost-effective tool for physical oceanographic observation in the open sea. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Correction of the effect of relative wind direction on wind speed derived by advanced microwave scanning radiometer     

Masanori Konda  Akira Shibata  Naoto Ebuchi  Kohei Arai 《Journal of Oceanography》2006,62(3):395-404

The sea surface wind speed (SSWS) derived by a microwave radiometer can be contaminated by changes of the brightness temperature owing to the angle between the sensor azimuth and the wind direction (Relative Wind Direction effect: RWD effect). We attempt to apply the method proposed by Konda and Shibata (2004) to the SSWS derived by Advanced Microwave Scanning Radiometer (AMSR) on Advanced Earth Observing Satellite II (ADEOS-II), in order to correct for the RWD effect. The improvement of accuracy of the SSWS estimation amounts to roughly 60% of the error caused by the RWD effect. Comparison with in situ observation at the Tropical Atmosphere Ocean (TAO) array shows that the root mean square error of the corrected SSWS is 1.1 ms⁻¹. It is found that the impact of the RWD effect on the estimation of the latent heat flux can amount to about 30 Wm⁻² on average. We applied the method to the SSWS derived by AMSR for Earth Observing System (AMSR-E) and obtained a similar result.  相似文献   

Estimation of wind drift current in the Soya Strait     

Wei Zhang  Naoto Ebuchi  Yasushi Fukamachi  Yutaka Yoshikawa 《Journal of Oceanography》2016,72(2):299-311

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Fluid Inclusion Study of Skarns in the Maruyama Deposit, the Kamioka Mine, Central Japan   总被引：1，自引：0，他引：1  

Naoto TAKENO  Takayuki SAWAKI  Hiroyasu MURAKAMI  Kazuhiro MIYAKE 《Resource Geology》1999,49(4):233-242

Abstract: Fluid inclusions in skarn minerals in the Maruyama deposit, the Kamioka mine, central Japan were studied. Homogenization temperatures (Th) of fluid inclusions in 48 skarn minerals (hedenbergite, andradite, epidote and quartz) were measured, and gas composition of fluid inclusions in 12 skarn minerals was measured with a quadrupole mass spectrometer. The maximum Th value of primary inclusions in hedenbergite is 380C with peaks around 360C. Primary inclusions in hedenbergite near contact between skarn and limestone have slightly lower Th values and their distribution has a tendency of long trail skirt toward low temperature, which indicates ceasing of skarnization coincides with temperature decrease. Fluid inclusions in andradite and quartz in the hedenbergite skarn have lower Th values, in this order, than those in hedenbergite. CH4–detected fluid inclusions are localized around the Maruyama fault. Gas composition of the fluid inclusions indicates that fluid trapped in the hedenbergite has CO2 content less than 1 mole % and is not in equilibrium with graphite.  相似文献   

Bifurcation current along the southwest coast of the Kii Peninsula   总被引：1，自引：0，他引：1  

Junichi Takeuchi  Naoto Honda  Yoshitaka Morikawa  Takashi Koike  Yutaka Nagata 《Journal of Oceanography》1998,54(1):45-52

Along the southwest coast of the Kii Peninsula, a bifurcation current is regularly observed. By using ADCP data taken on board the R/V Wakayama of the Wakayama Prefectural Fisheries Experimental Station, characteristics of this bifurcation current are analyzed. The occurrence frequency of the bifurcation current reaches about 70% in the period from 1988 to 1996. The bifurcation point appears to be changeable and occurs almost evenly between Cape Ichie and Cape Shionomisaki. The current divergence in the alongshore direction was also investigated. Positive divergence values dominated in the whole analyzed area, and an onshore current appears to be dominant along the southwest coast of the Kii Peninsula, except in 1990 when the Kuroshio flowed in a large meandering path.  相似文献