西南日本秋吉带石炭系高山(Ko-yama)灰岩群的褶皱构造     

Noriyuki INADA  Shigeyuki SUZUKI  Keisuke ISHIDA  Shinji YAMASHITA 《地球学报》2012,33(S1):24-24

The study area is located in Kawakami-cho, Okayama Prefecture, which is occupied by Lower Carboniferous to Middle Permian Ko-yama Limestone Group (Yokoyama et al., 1979), Permian Yoshii Group (Sano et al., 1987) and Triassic Nariwa Group (Tera-oka, 1959). The Nariwa Group unconformably covers the Paleozoic successions (Otoh, 1985). These succes-sions belong to the Akiyoshi Belt. The Ko-yama Limestone Group is composed mainly of massive limestone, with basic volcanic rocks, acidic tuff and chert. The group was dated by foraminifer and fusu-linid as Lower Carboniferous to Middle Permian (Yo-koyama et al., 1979).  相似文献   

西南日本秋吉带石炭系高山(Ko-yama)灰岩群的石炭纪(Visean – Moscovian)牙形石序列     

Keisuke ISHIDA  Sigeyuki SUZUKI  Noriyuki INADA  Shinji YAMASHITA 《地球学报》2012,33(S1):25-28

The Carboniferous conodont faunal succession of the lower part of Ko-yama Limestone Group was studied. The confirmed upper Visean–lower Moscovian lithostratigraphy of the group is characterized by the clastic carbonates with common association of the basaltic pyroclastics and some intercalation of spicular chert beds. The faunal succession of Gnathodus semiglaber (upper Visean), Gnathodus praebilineatus – Lochriea multinodosa (upper Visean), Lochriea ziegleri – Gnathodus girtyi girtyi s.l. (lower Serpukhovian), Neoganthodus symmetricus – Idiognathodus primulus (middle – upper Bashkirian), and Idiognathoides convexus – Gondolella clarki (lower Moscovian) faunas, appears in concordance with the lithostratigraphic order. The faunas are correlative with those from the conodont zones of the Hina, Atetsu, Akiyoshi and Omi limestone groups in the Akiyoshi Belt. The Visean/Serpukhovian boundary of the section was recognized by the FAD of Lochriea ziegleri.  相似文献   

Seasonal and spatial variations in the partial pressure of carbon dioxide in a eutrophic brackish lake,Lake Hamana,Japan     

Kubo  Atsushi  Yoshida  Keisuke  Suzuki  Kei 《Journal of Oceanography》2022,78(1):15-23

The dissolved inorganic carbon and total alkalinity in the surface brackish waters of Lake Hamana were investigated monthly from October 2017 to September 2019 at 14 stations. The partial pressure of carbon dioxide (pCO₂) in the surface water ranged from 29 to 1476 μatm and was undersaturated for atmospheric CO₂ during the observation periods, although most coastal waters were net source areas because of the large amount of terrestrial organic and inorganic carbon input. Since there was a strong negative correlation between pCO₂ and the dissolved oxygen, seasonal and temporal variations in pCO₂ were mainly derived from phytoplankton activity. The high phytoplankton activity induced by the effluents from sewage treatment plants, which was low in carbon and high in nitrogen. Therefore, in urbanized coastal waters with sewage treatment plants, such as the coastal waters of Japan, there is a possibility of shifting from weaker carbon dioxide source areas to sink areas. However, pCO₂ was oversaturated at the polluted river mouth, especially after high precipitation events due to the large carbon supply.

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Cellular model for sand dunes with saltation,avalanche and strong erosion: collisional simulation of barchans     

Atsunari Katsuki  Macoto Kikuchi  Hiraku Nishimori  Noritaka Endo  Keisuke Taniguchi 《地球表面变化过程与地形》2011,36(3):372-382

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The Triassic conodonts of the NW Malayan Kodiang Limestone revisited: Taxonomy and paleogeographic significance     

Keisuke Ishida  Francis Hirsch 《Gondwana Research》2011,19(1):22-36

The revision of the Middle and early Late Triassic conodonts in the Nogami (1968) collection from the NW Malaya Kodiang Limestone Formation provides clues to the multi-element reconstruction of Triassic Gondolellacea. Septi- to octomembrate multi-elements characterize the families Gondolellidae and Gladigondolellidae nov. fam. The distribution of cratognathodiform and ozarkodiniform P2 elements supports the hypothesis of sexual dimorphism in Gladigondolella rather than that of two genera. Pseudofurnishius murcianus confers a Southern Tethyan low latitude character to the Kodiang Limestone, a part of the Cimmerian string of terranes that in Triassic times formed a diagonal partition between the gradually closing Paleo-Tethys and the accordingly widening Neo-Tethys. Our findings suggest that such a realm stretched from the Southern Alps (Dinarids) in the West to Malaya (Shan Thai Terrane) in the East. Only the Eastern edge collided with Eurasia in the Late Triassic, forming the platform of Sundaland. Consequently, the Paleo-Tethys closure remained limited to SE Asia, while a substantial Paleo-Tethys still existed in Western direction, ending up in the Pindos and Vardar oceans. The Jurassic Neo-Tethys ocean extended south of the consolidated SE Asia block and Cimmerian string of terranes.  相似文献   

大气492 GHz亚毫米波不透明度的测量     

杨戟  孙成华  黄树频  大石雅寿  宫泽敬辅 《天文学报》2004,45(1):79-87

使用移动式亚毫米波望远镜(POST)在位于青藏高原海拔3200米的紫金山天文台德令哈射电天文观测站址测量地球大气492GHz频率处天顶方向的不透明度(τ0)的结果．在1999—2000年冬季和2000—2001年冬季的两个观测季节内累计共进行了约870个小时的测量，取得了25842组τ0的有效数据．对数据的统计表明，观测季节内τ0值主要分布在1．5—3．0之间．观测时段内大气不透明度τ0≤1．0的时间比例约占3％．在给出实测资料的基础上，将所测量的亚毫米波不透明度与国际现有亚毫米波台址的不透明度进行了初步比较．  相似文献   

Preliminary results of in-situ XCTD/CTD comparison test   总被引：4，自引：0，他引：4  

Keisuke Mizuno  Tomowo Watanabe 《Journal of Oceanography》1998,54(4):373-380

The current status of XCTD manufactured by the Tsurumi Seiki Co. is described based on XCTD/CTD comparison tests conducted in the Pacific and Indian Ocean in November 1996 and January 1997 respectively. The falling rates of used probes are generally consistent and differences between individual probes stay within a small range of +/−5 m through the full depth range (0–1000 m), although the rate is slightly different from the depth-time equation provided by the manufacturer. Temperature and salinity accuracy is estimated to be better than 0.05°C and 0.05 psu respectively. Comparison of vertical temperature/salinity sections of XCTD/CTD constructed separately along a line on which XCTD stations locate midway of CTD stations. The hydrographic structures obtained are generally consistent, and the difference of surface dynamic height (referred to 1000 db) is 0.03 dyn m in RMS.  相似文献   

Statistical analyses and modeling approaches to hydrodynamic characteristics in alluvial aquifer     

Chie Imagawa  Junichiro Takeuchi  Toshihiko Kawachi  Shunsuke Chono  Kei Ishida 《水文研究》2013,27(26):4017-4027

This study is aimed at quantifying the difference in aquifer's response to recharge between some different locations in a fan aquifer and a delta aquifer for a preliminary study of revealing mechanisms of water transport in alluvial aquifer. The aquifer's response to recharge is statistically quantified with the two viewpoints: (1) timing and volume of recharge and (2) time length of aquifer's holding water. For the first point, a statistical model that links precipitation and groundwater level is introduced, and its parameters are identified using correlation analysis. Our results show that the recharge rate at the toe is higher than that at the apex and at the delta. For the second point, the concept of ‘memory effect’ of aquifer is adopted and quantified using the autocorrelation and spectral analyses. Our results show that the memory effect is longer at the toe of fan than at the apex, and thus, a temporary increase of water level has about five times as long‐term influence on subsequent water levels at the toe of the fan as at the apex. This study demonstrates that the statistical analyses and modeling of hydrological data are useful for characterizing aquifer's hydrodynamics. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Better cars or older cars?: Assessing CO2 emission reduction potential of passenger vehicle replacement programs     

Shigemi Kagawa  Klaus Hubacek  Keisuke Nansai  Minori Kataoka  Shunsuke Managi  Sangwon Suh  Yuki Kudoh 《Global Environmental Change》2013,23(6):1807-1818

The primary motivation for the vehicle replacement schemes that were implemented in many countries was to encourage the purchase of new cars. The basic assumption of these schemes was that these acquisitions would benefit both the economy and the environment as older and less fuel-efficient cars were scrapped and replaced with more fuel-efficient models. In this article, we present a new environmental impact assessment method for assessing the effectiveness of scrappage schemes for reducing CO₂ emissions taking into account the rebound effect, driving behavior for older versus new cars and entire lifecycle emissions for during the manufacturing processes of new cars. The assessment of the Japanese scrappage scheme shows that CO₂ emissions would only decrease if users of the scheme retained their new gasoline passenger vehicles for at least 4.7 years. When vehicle replacements were restricted to hybrid cars, the reduction in CO₂ achieved by the scheme would be 6–8.5 times higher than the emissions resulting from a scheme involving standard, gasoline passenger vehicles. Cost–benefit analysis, based on the emission reduction potential, showed that the scheme was very costly. Sensitivity analysis showed that the Japanese government failed to determine the optimum, or target, car age for scrapping old cars in the scheme. Specifically, scrapping cars aged 13 years and over did not maximize the environmental benefits of the scheme. Consequently, modifying this policy to include a reduction in new car subsidies, focused funding for fuel-efficient cars, and modifying the target car age, would increase environmental benefits.  相似文献   

Chemical overprinting of magmatism by weathering: A practical method for evaluating the degree of chemical weathering of granitoids     

Atsushi Kamei  Keisuke Fukushi  Tetsuichi Takagi  Hitoshi Tsukamoto 《Applied Geochemistry》2012

Quantitative determination of the degree of chemical weathering of rocks is a fundamental task in environmental and engineering geology, and many weathering indices based on whole-rock chemistry have been proposed. However, most classical indices are of limited application to granitoids in a wide area, because these lithotypes generally exhibit wide chemical variation arising from their petrogenesis. The chemical evolution produced during rock weathering, therefore, overprints pre-existing magmatic chemical variation. This problem can cause many classical weathering indices to yield misleading results. This study proposes a method that compensates for the influence of petrogenesis on calculation of the weathering index. The method is based on a bivariate plot of the magmatic chemical variation (MCV) in granitoids, and the degree of chemical weathering (DCW). The MCV axis must be based on an element that reflects magmatic processes and is also relatively immobile during rock weathering. In this study TiO₂ contents are utilized for the MCV. The DCW axis is fundamentally defined by the ratios of more-mobile to less-mobile elements during weathering, and hence many classical indices can be applied. The improved value of the degree of chemical weathering (DCW_i) for a weathered rock is derived by:where MCV₁ is the measured composition (e.g. TiO₂ content) of the weathered rock. DCW₁ denotes the ratios of more-mobile to less-mobile elements of the weathered rock. The “s” parameter is the slope of the least square linear regression for fresh granitoids in the MCV–DCW relationship. MCV_CV is a correction factor which is given by the average point on the MCV axis (e.g. average TiO₂) of the fresh rocks. This method is useful for evaluating the degree of weathering of various granitoids, and enhances the practical application of many weathering indices.  相似文献