Zircon U-Pb and Lu-Hf ages of the Jurassic granites, Southwest Japan: A key for the tectonic correlation between Korea and Japan

Kenta Kawaguchi,Chang Whan Oh,Masaya Furusho,Satoshi Shibata 대한지질학회 2021 대한지질학회 학술대회 Vol.2021 No.10

Tectonic correlation between the Korean Peninsula and the Japanese Islands have long been discussed, but is still under debate and a challenging issue. This is because the limited occurrences of the correlatable rock units between them. The basement of the Korean Peninsula and the Japanese Islands are markedly different; Precambrian basement is dominant in the Korean Peninsula, while the Phanerozoic accretionary orogen is dominant in the Japanese Islands. However, the Jurassic granitoids is one of the common rock types between them. In this study, we focus on the Jurassic granitoids with figuring out the paleo-geographical position of the Japanese Islands along the erstwhile Korean Peninsula. The zircon U-Pb age dating of the 10 cm scale granite pebbles within the Cenozoic sedimentary sequence in the Noto Peninsula, the less studied area of northern part of the Hida Belt, revealed the weighted average ages of 183.6 ± 1.0 Ma (MSWD = 2.0, n = 25), 183.6 ± 1.1 Ma (MSWD = 2.0, n = 27), and 182.8 ± 1.4 Ma (MSWD = 2.6, n = 24). Zircon CL images, REE pattern, and Th/U ratio suggest that the obtained weighted average ages are the magmatic crystallization timing. Whole-rock geochemical data shows the moderately enriched LREE pattern with the weak Eu and Ce anomalies. In the primitive mantle-normalized multielement diagram, the granitoids display negative anomaly of the HFS elements such as Nb, Ta, P, and Ti. These geochemical features indicate that the 184–183 Ma granites were formed under the subduction related arc tectonic setting. Together with the previously reported data, the Jurassic granitoids in the Hida Belt show the age between 200–180 Ma and yield the arc tectonic setting. In the Korean Peninsula, Jurassic granitoids so-called “Daebo granites” (200–160 Ma) are widespread and formed under the arc tectonic setting. However, they show a clear selective trend in which the ~200–180 Ma granitoids are dominant in the southeastern (the Gyeongsang Basin and Yeongnam Massif) and northeastern (the Tumangang Belt) parts of the Korean Peninsula, while the later stage 180–160 Ma granitoids show the wide distribution on the continental side of the 200–180 Ma arc with northwest- and west-ward younging trend in the southern and northeastern parts of the Korean Peninsula (e.g., Kawaguchi and Oh, 2021). Considering those, the Hida Belt was located within the missing part of the 200–180 Ma arc belts between those developed in the southeastern and northeastern parts of the Korean Peninsula. Zircon Lu-Hf isotopic analysis of the 184–183 Ma granites revealed the εHf(t) values of –3 to +5 (an average of +1.4) in all the three dated samples. From the previous study, εHf(t) of zircon from the Early Jurassic granitoids (~200–180 Ma) in the Gyeonggi Massif and Ogcheon Belt show the negative values of ~–30 to –5, whereas those of the eastern part of the Yeongnam Massif yield the higher values of –5 to +10 (Lee et al ., 2016; Jo et al ., 2018; Cheong et al ., 2020). These isotopic features indicate that the 184–183 Ma Hida granites show the similar characteristics with those of the granitoids in the eastern part of the Yeongnam Massif. In addition, earliest to early Late Triassic zircons from the deformed granitic rocks in the Noto Peninsula area show the zircon εHf(t) value of –4.5 to –0.5 (an average of –2.0). These values are well matched to those of the Permo–Triassic granitoids in the Yeongnam Massif (Lee et al ., 2016). This study suggests that the zircon ages and εHf(t) values of the Hida granites show the common characteristics with the granitoids in the eastern part of the Yeongnam Massif. However, zircon εHf(t) value of the eastern part of the Gyeonggi Massif and the Taebaeksan Basin area are unclear, so the study in that area should have a key for further correlation between the Jurassic arc magmatism in the Korean Peninsula and the Japanese Islands.

A FEW APPROACHES TO RATIONAL SPATIAL STRUCTURES

Kawaguchi, Mamoru Korean Association for Spatial Structures 2001 한국공간구조학회지 Vol.1 No.1

A structural system developed and named 'Pantadome system' by the author has been applied to six major spatial structures of various shapes and dimensions in different corners of the world. It is a structures system (not a construction method) incorporation a temporary 'kinematic mechanism' in it for a rational construction of domical structures. Nara Convention Hall has recently been constructed successful on the principle of Pantadome System. In the present paper raison d'etre, principle and newly applied examples of Panatadome System are presented.

Construction of Three-Strut Tension Systems

Kawaguchi, K.,Lu, Z.Y Korean Association for Spatial Structures 2004 한국공간구조학회지 Vol.4 No.2

Dose Estimation Model for Terminal Buds in Radioactively Contaminated Fir Trees

Kawaguchi, Isao,Kido, Hiroko,Watanabe, Yoshito The Korean Association for Radiation Protection 2022 방사선방어학회지 Vol.47 No.3

Background: After the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, biological alterations in the natural biota, including morphological changes of fir trees in forests surrounding the power plant, have been reported. Focusing on the terminal buds involved in the morphological formation of fir trees, this study developed a method for estimating the absorbed radiation dose rate using radionuclide distribution measurements from tree organs. Materials and Methods: A phantom composed of three-dimensional (3D) tree organs was constructed for the three upper whorls of the fir tree. A terminal bud was evaluated using Monte Carlo simulations for the absorbed dose rate of radionuclides in the tree organs of the whorls. Evaluation of the absorbed dose targeted ¹³¹I, ¹³⁴Cs, and ¹³⁷Cs, the main radionuclides subsequent to the FDNPP accident. The dose contribution from each tree organ was calculated separately using dose coefficients (DC), which express the ratio between the average activity concentration of a radionuclide in each tree organ and the dose rate at the terminal bud. Results and Discussion: The dose estimation indicated that the radionuclides in the terminal bud and bud scale contributed to the absorbed dose rate mainly by beta rays, whereas those in 1-year-old trunk/branches and leaves were contributed by gamma rays. However, the dose contribution from radionuclides in the lower trunk/branches and leaves was negligible. Conclusion: The fir tree model provides organ-specific DC values, which are satisfactory for the practical calculation of the absorbed dose rate of radiation from inside the tree. These calculations are based on the measurement of radionuclide concentrations in tree organs on the 1-year-old leader shoots of fir trees. With the addition of direct gamma ray measurements of the absorbed dose rate from the tree environment, the total absorbed dose rate was estimated in the terminal bud of fir trees in contaminated forests.

Direct Analysis of Aerosol Particles by Atomic Emission and Mass Spectrometry

Kawaguchi, Hiroshi,Nomizu, Tsutomu,Tanaka, Tomokazu,Kaneco, Satoshi 한국분석과학회 1995 분석과학 Vol.8 No.4

A method for the direct determination of elemental content in each of aerosol particles by inductively coupled plasma atomic emission (ICP-AES) or mass spectrometry (ICP-MS) is described. This method is based upon the introduction of diluted aerosol into an ICP and the measurement of either the flash emission intensities of an atomic spectral line or ion intensities. A pulse-height analyzer is used for the measurement of the distribution of the elemental content. In order to calibrate the measuring system, monodisperse aerosols are used. The potentials of the method are shown by demonstrating the copper emission signals from the aerosols generated at a small electric switch, a study of the relation between the decreasing rate of particle number density and particle size, and measurements of calcium contents in the individual biological cells.

Ecophysiological Responses of Northern Birch Forests to the Changing Atmospheric CO₂ and O₃ Concentrations

Kawaguchi, Korin,Hoshika, Yasutomo,Watanabe, Makoto,Koike, Takayoshi Korean Society for Atmospheric Environment 2012 Asian Journal of Atmospheric Environment (AJAE) Vol.6 No.3

The effects on birch (Betula spp.) of elevated carbon dioxide ($CO_2$) and ozone ($O_3$), which are both increasing in the troposphere, are surveyed in detail based on the literature. Birches establish themselves in the open field after disturbances, and then become dominant trees in temperate or boreal forests. Ecophysiological approaches include the measurement of photosynthesis, biomass, growth, and survival of seedlings and trees. Elevated $CO_2$ levels give rise to a net enhancement of the growth of birch trees, whereas high $O_3$ generally reduces growth. Although the effects of the two are opposed, there is also an interactive effect. Basic physiological responses of the single genus Betula to $CO_2$ and $O_3$ are set out, and some data are summarized regarding ecological interactions between trees, or between trees and other organisms.

Basic Study of a Phase-Shifted Soft Switching High-Frequency Inverter with Boost PFC Converter for Induction Heating

Kawaguchi, Yuki,Hiraki, Eiji,Tanaka, Toshihiko,Nakaoka, Mutsuo The Korean Institute of Power Electronics 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.2

This paper is mainly concerned with a high frequency soft-switching PWM inverter suitable for consumer induction heating systems. The proposed system is composed of a soft switching chopper based boost PFC converter stage with passive snubber and phase shifted PWM controlled full bridge ZVZCS high frequency inverter stage. Its fundamental operating performances are illustrated and evaluated in the experimental results. Its effectiveness is substantially proved on the basis of the experimental results from a practical point of view.

A Possible Explanation for the Dominance of Chlorophyll in Pico and Nano-size Fractions in the Waters Around the South Shetland Islands

Kawaguchi, So,Shiomoto, Akihiro,Imai, Keiri,Tsarina, Yoriko,Yamaguchi, Hitomi,Noiri, Yoshifumi,Iguchi, Naoki,Kameda, Takahiko Korea Institute of Ocean Science Technology 2001 Ocean and Polar Research Vol.23 No.4

Ch1 a abundance, Ch1 a-specific productivity and phytoplankton growth rate in each size fraction (pico, $<2{\mu}m$; nano, $2-10{\mu}m$; micro, > $10{\mu}m$) in the waters around the South Shetland Islands (Ant-arctic Peninsula Area) were analysed. Although Ch1 a-specific productivity and growth rate were highest in micro-size fractions, ChI a abundance was highest in pico-size fractions. Selective removal of nano- and micro-size phytoplankton especially by krill and salp grazing, but not limitation of phytoplankton growth, seemed to be the major reason to explain this miss match between productivity and abundance of the phytoplankton community.

Membrane Structures - Their Characteristics and Various Applications -

Kawaguchi, Mamoru Korean Association for Spatial Structures 2001 한국공간구조학회지 Vol.1 No.2

A few characteristics of membrane structures which the author thinks important for design are described on the basis of his experience in research and design of this kind of structures. Different in behaviors of air-supported and air-inflated structures are first explained for a better understanding of these structures. Attention is drawn to unfavorable behaviors of an air-beam when it is reinforced by diagonal members. The shallowest membrane structure which can be made as an airdome is pursued, and its application to a metal membrane dome is shown. Attempts which have been made by the author seeking for the possibility of membrane structures made of metal sheet, plastic film with and without reinforcement are described with realized examples. A 100m long jumbo carp is explained as an example of a flying membrane.

Cut-off value of D-dimer for prediction of deep venous thrombosis before treatment in ovarian cancer

Ryuji Kawaguchi,Naoto Furukawa,Hiroshi Kobayashi 대한부인종양학회 2012 Journal of Gynecologic Oncology Vol.23 No.2

Objective: The purpose of the present study was to elucidate the incidence of deep venous thrombosis (DVT) before treatment in ovarian cancer and the appropriate cut-off value of D-dimer (DD) for the diagnosis of DVT. Methods: Between July 2007 and October 2008, eighty seven patients with presumed ovarian cancer (final diagnosis: ovarian cancer, n=59; borderline malignancy, n=28) were enrolled. Measurement of DD levels and subsequent venous ultrasonography were performed before treatment. Results: The mean DD level was 4.1 μg/mL. Subsequent venous ultrasonography revealed DVT in 14 of 87 (16.1%) patients (ovarian cancer, 12 cases; borderline malignancy, 2 cases). None were found to have developed DVT if they had a DD level of <1.5 μg/mL. If 1.5 μg/mL was used as a cut-off value for DD levels to diagnose DVT, sensitivity, specificity, positive predictive value, and negative predictive value were 100%, 61.6%, 33.3%, and 100%. There was noclinical onset of postoperative pulmonary thromboembolism. Conclusion: Our data suggest that presumed ovarian cancer patients with at least more than 1.5 μg/mL should be examined using venous ultrasonogaphy to detect DVT. Objective: The purpose of the present study was to elucidate the incidence of deep venous thrombosis (DVT) before treatment in ovarian cancer and the appropriate cut-off value of D-dimer (DD) for the diagnosis of DVT. Methods: Between July 2007 and October 2008, eighty seven patients with presumed ovarian cancer (final diagnosis: ovarian cancer, n=59; borderline malignancy, n=28) were enrolled. Measurement of DD levels and subsequent venous ultrasonography were performed before treatment. Results: The mean DD level was 4.1 μg/mL. Subsequent venous ultrasonography revealed DVT in 14 of 87 (16.1%) patients (ovarian cancer, 12 cases; borderline malignancy, 2 cases). None were found to have developed DVT if they had a DD level of <1.5 μg/mL. If 1.5 μg/mL was used as a cut-off value for DD levels to diagnose DVT, sensitivity, specificity, positive predictive value, and negative predictive value were 100%, 61.6%, 33.3%, and 100%. There was noclinical onset of postoperative pulmonary thromboembolism. Conclusion: Our data suggest that presumed ovarian cancer patients with at least more than 1.5 μg/mL should be examined using venous ultrasonogaphy to detect DVT.