Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
5 Ma) orogenic systems: a case study from the Japanese Islands末岡 茂; 田上 高広*
Progress in Earth and Planetary Science (Internet), 12, p.59_1 - 59_20, 2025/07
被引用回数：1 パーセンタイル：35.07(Geosciences, Multidisciplinary)Low-temperature thermochronology, including fission track (FT) and (U-Th-Sm)/He thermochronometry, has been widely used to constrain the exhumation history of orogenic systems over timescales of 10
-10
years. This research employed simple numerical modeling to evaluate the applicability of low-temperature thermochronometry to young orogenic systems uplifted in geologically recent periods such as the Pliocene and Quaternary, such as those in the Japanese Islands. Such orogenic systems are at the younger limit of the applicability because this time scale corresponds to the younger limit of applicability of the major low-temperature thermochronometers and also corresponds to the minimum period required for an orogenic system to be denuded by more than 2-3 km after the startof uplift, which is the lower limit detectable by the major low-temperature thermochronometers. Time-temperature paths were generated for varying uplift rates, uplift onsets, and model onsets (equivalent to the rock formation age). These paths were then converted into cooling ages for four thermochronometers: apatite and zircon FT and (U-Th-Sm)/He dating. The calculations were conducted using two models: a constant-elevation model and an increasingelevation model. The modeling results are summarized in look-up tables, illustrating relationships between uplift rates, uplift onsets, rock formation ages and ratios of cooling age and rock formation age. The results indicate that differences in formation age and elevation change minimally impact cooling ages. The modeled dates generally alignwith measured cooling ages in regions where the rate and timing of uplift are well constrained, supporting the reliability of the modeling approach. Consequently, the derived relationships between uplift rates and cooling ages provide a practical method for roughly classifying mountain uplift rates based on cooling ages, without requiring complex simulations. Finally, these relationships were applied to previously reported cooling ages to visualize the distribution of uplift rates across the Japanese Islands over the past few million years. These results provide a benchmark for the low-temperature thermochronological studies, not only in the Japanese Islands, but also in mobile belts around the world that have begun to uplift in the past few million years.
土屋 晴文; 日比野 欣也*; 川田 和正*; 大西 宗博*; 瀧田 正人*; 宗像 一起*; 加藤 千尋*; 霜田 進*; Shi, Q.*; Wang, S.*; et al.
Progress of Earth and Planetary Science (Internet), 11, p.26_1 - 26_14, 2024/05
被引用回数：3 パーセンタイル：33.58(Geosciences, Multidisciplinary)From 1998 to 2017, neutron monitors located at an altitude of 4300 m on the Tibetan plateau detected 127 long-duration bursts of high-energy radiation in association with thunderclouds. These bursts typically lasted for 10-40 min, and 89% of them occurred between 10:00 and 24:00 local time. They were also found to be more likely to occur at night, especially during 18:00-06:00 local time period. The observed diurnal and seasonal variations in burst frequency were consistent with the frequencies of lightning and precipitation on the Tibetan plateau. Based on 19 years of data, the present study suggests that an annual variation in burst frequency has a periodicity of 16 years and a lag of 3 years relative to solar activity.
Tang, P.*; 北 和之*; 五十嵐 康人*; 佐藤 志彦; 畑中 恒太郎*; 足立 光司*; 木名瀬 健*; 二宮 和彦*; 篠原 厚*
Progress in Earth and Planetary Science (Internet), 9(1), p.17_1 - 17_15, 2022/03
被引用回数：10 パーセンタイル：51.30(Geosciences, Multidisciplinary)The deposition of insoluble radiocesium bearing microparticles (CsMPs), which were released from the Fukushima Daiichi Nuclear Power Plant (F1NPP) accident in March 2011, has resulted in the widespread contamination of eastern Japan. Obviously, these deposited insoluble CsMPs may become the secondary contamination sources by atmospheric migration or other environmental transferring process, however, the understanding of the transport mechanism remains non-elucidation, and the relevant evidence has not been directly provided. This study, for the first time, provides the direct evidence for the resuspension of these insoluble CsMPs to the atmosphere from (1) proximity of 
Cs radioactivity and resemblance of the morphology and the elemental compositions of CsMPs in the samples of soil and aerosol derived from the same sampling site, (2) the special characteristics of the resuspended CsMPs of which the ratios of Na/Si, K/Si and/or Cs/Si were smaller than those from the initially released CsMPs collected at either long distance or near F1NPP, which can be ascribed to the slowly natural corrosion of CsMPs by the loss of the small amount of soluble contents in CsMPs, and (3) high CsMPs concentration of 10 granules/gram in the surface soil of our sampling site, and high resuspension frequency of CsMPs in spring when predominant suspended particles were soil dust.
宗本 隆志; 大森 一秋; 岩月 輝希
Progress in Earth and Planetary Science (Internet), 1, p.28_1 - 28_19, 2014/12
Colloids and their association with analogue elements (U and rare earth elements: REEs) in deep granitic groundwater were investigated at the Mizunami Underground Research Laboratory (MIU). From the perspective of the mobilization of colloids, technical methods for the quality control of groundwater and colloid sampling were proposed. The groundwater and colloids were sampled from boreholes and underground excavations by ultrafiltration by using different pore size membrane.
