The effects of a constant volume deformation on the magnetization of an artificial sediment     

Kenneth P. Kodama  Allen Cox 《Earth and Planetary Science Letters》1978,38(2):436-442

Anhysteretic remanent magnetization (DC field = 1 Oe, peak AC field = 1000 Oe) was given to an artificial sediment consisting of a kaolinite matrix and a 0.03% magnetic fraction of needle-shaped magnetite grains. The mean grain size of the clay flakes and the magnetite needles was approximately 0.5 μm. This sediment was subjected to plane strain while maintaining constant volume. The axis of maximum compression was shortened by as much as 331/3%, which produced no significant change in the direction of magnetization with a decrease in intensity of 28%. A continuous deformation model, in which the magnetite needles are embedded in a plastically deforming linearly homogeneous medium, failed to explain these results. A discontinuous deformation model was more successful. In this model, deformation occurs mainly in shear zones bounding blocks which translate along the shears. Only those magnetite grains in the shear zones rotate, and from symmetry considerations no net change in the direction of magnetization is predicted. Because magnetite grains rotate in opposite directions in complementary sets of shears, the model predicts a decrease in intensity comparable to that which was observed.  相似文献   

Inventory of perennial snow patches in Central Japan     

Prof. Dr. K. Higuchi  T. Iozawa  Dr. Y. Fujii  H. Kodama 《GeoJournal》1980,4(4):303-311

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A deficit of faint red galaxies in the possible large-scale structures around the RDCS J1252.9−2927 cluster at z= 1.24     

Masayuki Tanaka  Tadayuki Kodama  Masaru Kajisawa  Richard Bower  Ricardo Demarco  Alexis Finoguenov  Chris Lidman  Piero Rosati 《Monthly notices of the Royal Astronomical Society》2007,377(3):1206-1214

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Holocene millennial-scale climate variations documented by multiple lake-level proxies in sediment cores from Hurleg Lake,Northwest China   总被引：2，自引：0，他引：2  

Cheng Zhao  Zicheng Yu  Yan Zhao  Emi Ito  Kenneth P. Kodama  Fahu Chen 《Journal of Paleolimnology》2010,44(4):995-1008

Millennial-scale climate variability has not been well documented in arid northwest China due to the scarcity of high-resolution, well-dated paleoclimate records. Here we present multi-proxy records from sediment cores taken in freshwater Hurleg Lake on the northeastern Tibetan Plateau, which reveal millennial-scale lake-level and climate variations over the past 8,000 years. This high-elevation region is very sensitive to large-scale climate change, thus allowing us to better understand Holocene climate variations in East Asia. The lake-level record, derived from lithology, magnetic mineralogy, carbonate isotopes, ostracode shell isotopes and trace elements, X-ray fluorescence (XRF), and gray scale data, indicates a highly variable and generally dry climate from 7.8 to 1 ka (1 ka = 1,000 cal year BP), and a relatively stable and wet climate after 1 ka. Superimposed on this general trend, six dry intervals at 7.6–7.2 ka, 6.2–5.9 ka, 5.3–4.9 ka, 4.4–3.8 ka, 2.7–2.4 ka, and 1.7–1.1 ka were detected from the high-resolution carbonate content and XRF data. The generally dry climate between 7.8 and 1 ka was almost synchronous with the decrease of East Asian and Indian monsoon intensities shortly after 8 ka. The six dry intervals can be correlated with weak monsoon events recorded in the East Asia and Indian monsoon regions, as well as the North Atlantic cold events. Our data suggest that millennial-scale monsoon variations could cause highly variable climate conditions in arid northwest China during the Holocene. These millennial-scale climate variations may reflect changes in solar variation and/or changes in oceanic and atmospheric circulation.  相似文献   

Diurnal variations in streamflow and water quality during the summer dry season     

Daiji Kobayashi  Yuji Kodama  Yoshiyuki Ishii  Yumiko Tanaka  Keisuke Suzuki 《水文研究》1995,9(7):833-841

In a headwater basin covered with boreal forest in northern Japan, the summer dry flow was monitored each summer from 1985 to 1993. Streamflow and specific electrical conductance fluctuated diurnally and these variations were attributed to daytime evapotranspiration. In 1989, the daytime reduction in streamflow and conductance were accompanied by a reduction in the HCO^?₃ concentration. The low flow hydrograph was separated into two components using HCO^?₃ and Cl^? concentrations in August 1989, assuming low flow to be a mixture of delayed subsurface flow and of quick shallow flow. The slight diurnal variation in the ratio of shallow flow to subsurface flow caused the diurnal variation in conductance by changing the HCO^?₃ concentration.  相似文献   

A photometric study of the ages and metallicities of early-type galaxies in A 2218     

Ian Smail  Harald Kuntschner  T. Kodama  G. P. Smith  C. Packham  †  A. S. Fruchter  R. N. Hook 《Monthly notices of the Royal Astronomical Society》2001,323(4):839-849

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