Recursos de colección

Hokkaido University Collection of Scholarly and Academic Papers (135.711 recursos)

HUSCAP (Hokkaido University Collection of Scholarly and Academic Papers) contains peer-reviewed journal articles, proceedings, educational resources and any kind of scholarly works of Hokkaido University.

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Mostrando recursos 1 - 20 de 25

  1. Mapping of subsurface karst structure with gamma ray and electrical resistivity profiles : a case study from Pokhara valley, central Nepal

    Gautam, Pitambar; Pant, Surendra Raj; Ando, Hisao
    Electrical resistivity (sounding with Schlumberger array and dipole-dipole imaging) and natural gamma ray intensity measurements were made over the karst features (subsurface flow-channels, solution cavities, sinkholes) in the Pokhara valley, central Nepal. In the Powerhouse area, the upper 60-80 m section of the basin-filling Quaternary sediments is represented by layered clastic sediments (gravel, silt, clay) that are represented by KQ-type (ρ1<ρ2>ρ3>ρ4) electrical sounding curves. The true electrical resistivity of the layers has a wide range of variation (a few hundreds to several tens of thousands of ohm.m) such that it is possible to determine both the vertical and lateral subsurface...

  2. Mapping of subsurface karst structure with gamma ray and electrical resistivity profiles : a case study from Pokhara valley, central Nepal

    Gautam, Pitambar; Pant, Surendra Raj; Ando, Hisao
    Electrical resistivity (sounding with Schlumberger array and dipole-dipole imaging) and natural gamma ray intensity measurements were made over the karst features (subsurface flow-channels, solution cavities, sinkholes) in the Pokhara valley, central Nepal. In the Powerhouse area, the upper 60-80 m section of the basin-filling Quaternary sediments is represented by layered clastic sediments (gravel, silt, clay) that are represented by KQ-type (ρ1<ρ2>ρ3>ρ4) electrical sounding curves. The true electrical resistivity of the layers has a wide range of variation (a few hundreds to several tens of thousands of ohm.m) such that it is possible to determine both the vertical and lateral subsurface...

  3. Depositional chronology and fabric of Siwalik group sediments in Central Nepal from magnetostratigraphy and magnetic anisotropy

    Gautam, Pitambar; Rösler, Wolfgang
    Magnetostratigraphic research, undertaken within the past 15 years in the Siwaliks distributed along 400 km of the Sub-Himalaya in central Nepal, has proved that the sediments possess highly reliable hematite-based primary detrital remanent magnetization suitable to determine depositional chronology. In order to bring out the polarity sequences in a common chronological frame, all available data are newly correlated to the latest global magnetic polarity time scale of Cande and Kent (1995). Chronological data presented are referred in relation to the diverse lithological nomenclature to the formations whose ages are not constrained by isotopic or paleontologic ages. The age of the...

  4. Depositional chronology and fabric of Siwalik group sediments in Central Nepal from magnetostratigraphy and magnetic anisotropy

    Gautam, Pitambar; Rösler, Wolfgang
    Magnetostratigraphic research, undertaken within the past 15 years in the Siwaliks distributed along 400 km of the Sub-Himalaya in central Nepal, has proved that the sediments possess highly reliable hematite-based primary detrital remanent magnetization suitable to determine depositional chronology. In order to bring out the polarity sequences in a common chronological frame, all available data are newly correlated to the latest global magnetic polarity time scale of Cande and Kent (1995). Chronological data presented are referred in relation to the diverse lithological nomenclature to the formations whose ages are not constrained by isotopic or paleontologic ages. The age of the...

  5. Magnetism and granulometry of Pleistocene sediments of Dhapasi section, Kathmandu (Nepal) : implications for depositional age and paleoenvironment

    Gautam, Pitambar; Sakai, Tetsuya; Paudayal, Khum Narayan; Bhandari, Sudarshan; Gyawali, Babu Ram; Gautam, Chinta Mani; Rijal, Moti Lal
    A 28-m thick exposure of the younger stage deposits of Kathmandu Valley fluvio-deltaic deposits at Dhapasi has been studied for magnetic susceptibility (MS), remanent magnetization (RM), grain size characteristics of fine-grained sediments, and sedimentary fabric by anisotropy of magnetic susceptibility (AMS) . In situ volume MS (κ; in 10^[-3] SI) of the natural sediments ranges from 0.001 to 0.15, with lower range (<0.02) restricted to quartz-rich coarse sand, whereas the uppermost 20-cm thick section affected by anthropogenic activity exhibits enhanced range (0.15-2). RM of specimens from some 80 levels reveals predominantly normal polarity except for a part of ca. 80cm...

  6. Magnetism and granulometry of Pleistocene sediments of Dhapasi section, Kathmandu (Nepal) : implications for depositional age and paleoenvironment

    Gautam, Pitambar; Sakai, Tetsuya; Paudayal, Khum Narayan; Bhandari, Sudarshan; Gyawali, Babu Ram; Gautam, Chinta Mani; Rijal, Moti Lal
    A 28-m thick exposure of the younger stage deposits of Kathmandu Valley fluvio-deltaic deposits at Dhapasi has been studied for magnetic susceptibility (MS), remanent magnetization (RM), grain size characteristics of fine-grained sediments, and sedimentary fabric by anisotropy of magnetic susceptibility (AMS) . In situ volume MS (κ; in 10^[-3] SI) of the natural sediments ranges from 0.001 to 0.15, with lower range (<0.02) restricted to quartz-rich coarse sand, whereas the uppermost 20-cm thick section affected by anthropogenic activity exhibits enhanced range (0.15-2). RM of specimens from some 80 levels reveals predominantly normal polarity except for a part of ca. 80cm...

  7. Neo-Science of Natural History : An Interdisciplinary Program for the 21st Century Center of Excellence at Hokkaido University, Japan

    Suzuki, Noriyuki; Mawatari, Shunsuke F.; Okada, Hisatake
    The 21st Century Center of Excellence (COE) Program for the "Neo-Science of Natural History" was launched in 2003 as a 5-year-long, grant-in-aid program awarded by the Japanese Ministry of Education, Culture, Science, and Technology (MEXT). The 21st Century COE Program is an initiative by MEXT to further strengthen education and research activities at Japanese universities. The acceptance of applications for proposed COE programs by MEXT started in 2002 and has continued for 3 consecutive years. Of the 611 applications submitted in FY2003, when we applied, a total of 133 applications were approved together with this COE Program entitled as the...

  8. Depositional Environments Revealed From Biomarkers in Sediments Deposited During the Mid-Cretaceous Oceanic Anoxic Events (OAEs) in the Vocontian Basin (SE France)

    Okano, Kazuki; Sawada, Ken; Takashima, Reishi; Nishi, Hiroshi; Okada, Hisatake
    Biomarker and total sulfur (TS) analyses were carried out on laminated black shales and massive marls collected from Goguel level (OAE1a) and the Kilian and the Paquier levels (OAE1b) in the Vocontian Basin in southeast France. Total sulfur content and concentrations of thiophenes are abundant in the Goguel level, whereas furans and retene, which are originated from terrestrial plants, are predominant in the Kilian and the Paquier levels. These results suggests the expansion of intense anoxic waters to deep ocean during the deposition of Goguel level rather than during the periods covered by the Kilian and the Paquier levels. In...

  9. Experimental Study of the Use of the Stable Isotopic Composition of Calcareous Microfossils in Shallow Marine Sediments for Reconstructing Paleoenvironment, and a Comparison with the MART Index

    Ishimura, Toyoho; Dick, Matthew H.; Takashima, Reishi; Hirose, Masato; Gautam, Pitambar; Nishi, Hiroshi; Tsunogai, Urumu
    For reconstruction of paleoenvironments using the isotopic compositions of shallow-water microfossils, especially benthic microfossils at high latitudes, difficulties arise due to variation in environmental factors, including seasonal temperature, depth, water currents, and habitat. In this study, we applied a microscale technique to determine stable carbon and oxygen isotopic ratios in shallow-water calcareous benthic microfossils (foraminifera and bryozoans), in order to choose suitable species for reconstructing paleoenvironmental changes in a Pleistocene shallow marine setting. We compared isotopic trends in Cibicides refulgens, a shallow water epibenthic foraminifer, with the mean annual range of temperature (MART) based on bryozoan analyses. We found no...

  10. Experimental Study of the Use of the Stable Isotopic Composition of Calcareous Microfossils in Shallow Marine Sediments for Reconstructing Paleoenvironment, and a Comparison with the MART Index

    Ishimura, Toyoho; Dick, Matthew H.; Takashima, Reishi; Hirose, Masato; Gautam, Pitambar; Nishi, Hiroshi; Tsunogai, Urumu
    For reconstruction of paleoenvironments using the isotopic compositions of shallow-water microfossils, especially benthic microfossils at high latitudes, difficulties arise due to variation in environmental factors, including seasonal temperature, depth, water currents, and habitat. In this study, we applied a microscale technique to determine stable carbon and oxygen isotopic ratios in shallow-water calcareous benthic microfossils (foraminifera and bryozoans), in order to choose suitable species for reconstructing paleoenvironmental changes in a Pleistocene shallow marine setting. We compared isotopic trends in Cibicides refulgens, a shallow water epibenthic foraminifer, with the mean annual range of temperature (MART) based on bryozoan analyses. We found no...

  11. Rockmagnetic Characterization of the Setana and Chiraigawa Formations in SW Hokkaido (Soebetsu River, Kuromatsunai)

    Gautam, Pitambar; Takashima, Reishi; Dick, Matthew H.; Kanamatsu, Toshiya; Rijal, Moti L.; Nishi, Hiroshi; Mawatari, Shunsuke F.
    Rockmagnetic investigations were conducted on sediments constituting the upper part of the Setana Formation and the Chiraigawa Formation, of Plio-Pleistocene age, exposed along the Soebetsu River in the vicinity of Kuromatsunai town, Hokkaido. Average mass-specific low-field magnetic susceptibility (χ) had the lowest value (15.2 x 10^[-8] m^3kg^[-1]) at one site in the Kuromatsunai Formation, but higher values represented by wide ranges of (26.1-132.2) x 10^[-8] m^3kg^[-1] and (135.6-870.1) x 10^[-8] m^3kg^[-1] characterized the Chiraigawa and Setana Formations, respectively. Magnetomineralogical analyses by isothermal remanence (IRM) acquisition, Curie temperature determinations, and electron microscopy aided with energy dispersive X-ray analysis suggest the presence...

  12. Rockmagnetic Characterization of the Setana and Chiraigawa Formations in SW Hokkaido (Soebetsu River, Kuromatsunai)

    Gautam, Pitambar; Takashima, Reishi; Dick, Matthew H.; Kanamatsu, Toshiya; Rijal, Moti L.; Nishi, Hiroshi; Mawatari, Shunsuke F.
    Rockmagnetic investigations were conducted on sediments constituting the upper part of the Setana Formation and the Chiraigawa Formation, of Plio-Pleistocene age, exposed along the Soebetsu River in the vicinity of Kuromatsunai town, Hokkaido. Average mass-specific low-field magnetic susceptibility (χ) had the lowest value (15.2 x 10^[-8] m^3kg^[-1]) at one site in the Kuromatsunai Formation, but higher values represented by wide ranges of (26.1-132.2) x 10^[-8] m^3kg^[-1] and (135.6-870.1) x 10^[-8] m^3kg^[-1] characterized the Chiraigawa and Setana Formations, respectively. Magnetomineralogical analyses by isothermal remanence (IRM) acquisition, Curie temperature determinations, and electron microscopy aided with energy dispersive X-ray analysis suggest the presence...

  13. Geology and Sedimentary Environments of the Pleistocene Setana Formation in the Kuromatsunai District, Southwestern Hokkaido, Japan

    Takashima, Reishi; Dick, Matthew H.; Nishi, Hiroshi; Mawatari, Shunsuke F.; Nojo, Ayumu; Hirose, Masato; Gautam, Pitambar; Nakamura, Keiichi; Tanaka, Takayuki
    The Pleistocene Setana Formation is exposed along the axial zone of the Kuromatsunai district, southwestern Hokkaido Island, and is divided into the Nakasato Conglomerate Member and Soebetsu Sandstone Member. The Nakasato Conglomerate Member consists of medium- to coarsegrained sandstone that accumulated in shoreface, delta, and channel systems. This member is correlated with the overlapping interval between the CN13b calcareous nannofossil zone and the Neogloboquadrina pachyderma (s) / Neogloboquadrina incompta planktonic foraminiferan zone, which indicates an age of 1.2-1.0 Ma. The Soebetsu Sandstone Member is made up of sandy siltstone to very fine-grained sandstone and includes several beds of shell concentrations....

  14. Geology and Sedimentary Environments of the Pleistocene Setana Formation in the Kuromatsunai District, Southwestern Hokkaido, Japan

    Takashima, Reishi; Dick, Matthew H.; Nishi, Hiroshi; Mawatari, Shunsuke F.; Nojo, Ayumu; Hirose, Masato; Gautam, Pitambar; Nakamura, Keiichi; Tanaka, Takayuki
    The Pleistocene Setana Formation is exposed along the axial zone of the Kuromatsunai district, southwestern Hokkaido Island, and is divided into the Nakasato Conglomerate Member and Soebetsu Sandstone Member. The Nakasato Conglomerate Member consists of medium- to coarsegrained sandstone that accumulated in shoreface, delta, and channel systems. This member is correlated with the overlapping interval between the CN13b calcareous nannofossil zone and the Neogloboquadrina pachyderma (s) / Neogloboquadrina incompta planktonic foraminiferan zone, which indicates an age of 1.2-1.0 Ma. The Soebetsu Sandstone Member is made up of sandy siltstone to very fine-grained sandstone and includes several beds of shell concentrations....

  15. Integration of magnetism and heavy metal chemistry of soils to quantify the environmental pollution in Kathmandu, Nepal

    Gautam, Pitambar; Blaha, Ulrich; Appel, Erwin
    Soil profiles of Kathmandu urban area exhibit significant variations in magnetic susceptibility (χ) and saturation isothermal remanence (SIRM), which can be used to discriminate environmental pollution. χ can be used to delineate soil intervals by depth into normal ( < 10^[-7] m^3 kg^[-1]), moderately enhanced (10^[-7] to <10^[-6] m^3 kg^[-1]) and highly enhanced (≥10^[-6] m^3 kg^[-1]). Soils far from road and industrial sites fall commonly into 'normal' category. Close to a road corridor, soils at several cm depth possess highest χ, which remains high within the upper 20 cm interval, and decreases with depth through 'moderately magnetic' to 'normal' at...

  16. Integration of magnetism and heavy metal chemistry of soils to quantify the environmental pollution in Kathmandu, Nepal

    Gautam, Pitambar; Blaha, Ulrich; Appel, Erwin
    Soil profiles of Kathmandu urban area exhibit significant variations in magnetic susceptibility (χ) and saturation isothermal remanence (SIRM), which can be used to discriminate environmental pollution. χ can be used to delineate soil intervals by depth into normal ( < 10^[-7] m^3 kg^[-1]), moderately enhanced (10^[-7] to <10^[-6] m^3 kg^[-1]) and highly enhanced (≥10^[-6] m^3 kg^[-1]). Soils far from road and industrial sites fall commonly into 'normal' category. Close to a road corridor, soils at several cm depth possess highest χ, which remains high within the upper 20 cm interval, and decreases with depth through 'moderately magnetic' to 'normal' at...

  17. Environmental magnetic approach towards the quantification of pollution in Kathmandu urban area, Nepal

    Gautam, Pitambar; Blaha, Ulrich; Appel, Erwin; Neupane, Ghanashyam
    The Kathmandu Valley is a bowl-shaped intermontane basin, which occupies an area of 583 km2 in the heart of the Himalayas, with its floor at ca. 1400 m and the surrounding mountains attaining a height of 2000-2800 m. It is inhabited by ca. 1.5 million people, concentrated mostly in three cities, Kathmandu, Patan and Bhaktapur. Due to rapid but uncontrolled urbanization and factors such as traffic movement, emissions from brick-kilns, cement factory, other industrial activities, waste disposal and biomass burning, environmental pollution has been constantly increasing adversely affecting land, water, air and biological systems. In order to quantify the degree of...

  18. Environmental magnetic approach towards the quantification of pollution in Kathmandu urban area, Nepal

    Gautam, Pitambar; Blaha, Ulrich; Appel, Erwin; Neupane, Ghanashyam
    The Kathmandu Valley is a bowl-shaped intermontane basin, which occupies an area of 583 km2 in the heart of the Himalayas, with its floor at ca. 1400 m and the surrounding mountains attaining a height of 2000-2800 m. It is inhabited by ca. 1.5 million people, concentrated mostly in three cities, Kathmandu, Patan and Bhaktapur. Due to rapid but uncontrolled urbanization and factors such as traffic movement, emissions from brick-kilns, cement factory, other industrial activities, waste disposal and biomass burning, environmental pollution has been constantly increasing adversely affecting land, water, air and biological systems. In order to quantify the degree of...

  19. Magnetic susceptibility of dust-loaded leaves as a proxy of traffic-related heavy metal pollution in Kathmandu city, Nepal

    Gautam, Pitambar; Blaha, Ulrich; Appel, Erwin
    Dust-loaded tree leaves from Kathmandu have been analyzed for magnetic susceptibility (χ) and heavy metal (HM) contents. For 221 samples of leaves of cypress (mainly Cupressus corneyana), silky oak (Grevillea robusta) and bottlebrush (Callistemon lanceolatus), χ has a range of (0.01-54)×10^[-8] m^3 kg^[-1] with a median of about 10.0×10^[-8] m^3 kg^[-1]. Trees situated close to the busy road intersections, near the main bus station and sectors of roads with steep slope yield elevated susceptibility. Chemical analysis of 20 samples of varying susceptibility by atomic absorption spectrometry yields the following maximum HM contents: Fe (1.3 wt%), Mn (281.9 ppm), Zn (195.2...

  20. Magnetic susceptibility of dust-loaded leaves as a proxy of traffic-related heavy metal pollution in Kathmandu city, Nepal

    Gautam, Pitambar; Blaha, Ulrich; Appel, Erwin
    Dust-loaded tree leaves from Kathmandu have been analyzed for magnetic susceptibility (χ) and heavy metal (HM) contents. For 221 samples of leaves of cypress (mainly Cupressus corneyana), silky oak (Grevillea robusta) and bottlebrush (Callistemon lanceolatus), χ has a range of (0.01-54)×10^[-8] m^3 kg^[-1] with a median of about 10.0×10^[-8] m^3 kg^[-1]. Trees situated close to the busy road intersections, near the main bus station and sectors of roads with steep slope yield elevated susceptibility. Chemical analysis of 20 samples of varying susceptibility by atomic absorption spectrometry yields the following maximum HM contents: Fe (1.3 wt%), Mn (281.9 ppm), Zn (195.2...

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