The possibility of inferring paleoseismicity from paleomagnetic dating of speleothems, western Japan   总被引：2，自引：0，他引：2  

Hayao Morinaga  Takafumi Yonezawa  Yasuhisa Adachi  Hiroo Inokuchi  Hiroya Goto  Katsumi Yaskawa 《Tectonophysics》1994,230(3-4):241-248

Paleomagnetic dating of continuously growing stalagmites by comparing their paleomagnetic records with a standard record, has been applied to study the paleoseismic history of a region of western Japan. Three stalagmites (speleothems), which are assumed to have started growing since collapse of the limestone blocks on which they are formed, were collected from two limestone caves located below the Akiyoshi plateau, western Japan. From the paleomagnetic results, it is estimated that they began to grow at 6000, 2500 and 2000 yr B.P., respectively. On the assumption that their growth began immediately after their host limestone blocks fell, these three ages are interpreted to indicate the dates of past earthquakes in this region which triggered the break-off and fall of the blocks. Earthquakes are suggested because many huge collapsed limestone blocks and speleothems are observed in many caves in this region.  相似文献   

Wet deposition of radionuclides derived from the Chernobyl accident     

Katsumi Hirose  Sukeyoshi Takatani  Michio Aoyama 《Journal of Atmospheric Chemistry》1993,17(1):61-71

Chernobyl radioactivity in precipitation was measured at Tsukuba, Japan, as were both surface-air concentrations and particle-size distributions of Chernobyl-released radionuclides. To understand the wet removal processes of the Chernobyl radionuclides, i.e.¹³⁷Cs,¹⁰³Ru, and⁹⁰Sr, wet deposition velocities were calculated. The wet deposition velocities of the Chernobyl radioactivity for individual rainfall events varied largely. The wet deposition velocity is given as the product of washout ratio and rainfall rate. Typically, it was found that the washout ratios of⁹⁰Sr are systematically larger than those of¹³⁷Cs. In order to explain this fact, we examined the relationship between the washout ratios and particle sizes of radionuclide-bearing aerosols. A positive correlation between corrected washout ratios and particle size was found with a particle diameter range from 0.35 to 1.2 µm. The result strongly suggests that the factors controlling the wet removal of the Chernobyl radioactivity for individual rainfall events are surface air concentration, particle size, and rainfall rate, rather than precipitation amount, which is in agreement with previous understandings. This suggests that high contamination areas of radioactivity are formed during heavy rainfall events with high rainfall rates in the case of tropospheric injection such as the Chernobyl accident.  相似文献   

Infrared stimulated luminescence and radiofluorescence dating of aeolian sediments from Hungary     

Ágnes Novothny  Manfred Frechen  Erzsébet Horváth  Matthias Krbetschek  Sumiko Tsukamoto 《Quaternary Geochronology》2010,5(2-3):114-119

Anomalous fading of the infrared stimulated luminescence (IRSL) signal from the polymineral fine-grain and K-feldspar fractions of aeolian sediments from Hungary has been studied. The samples in this study have previously been dated using the multiple aliquot additive dose (MAAD) protocol to measure the IRSL signal. The IRSL measurements using MAAD were conducted ～4 weeks after the irradiation, making it difficult to assess to what extent these age estimates were affected by anomalous fading. In this study, equivalent doses were obtained using the single aliquot regenerative dose (SAR) protocol. The fading rate for each sample was calculated using the different IRSL components and different parts of the decay curve. For each sample, the middle part of the decay curve always showed a lower fading rate than the initial part of the decay curve. The difference between the fading rates for different parts of the decay curve was greater for the K-feldspars than for the polymineral fine grains. Fading corrected ages were calculated by integrating both the initial and the middle part of the decay curve. These ages were compared with optically stimulated luminescence (OSL) ages from quartz, infrared radiofluorescence (IR-RF) ages obtained from K-feldspars and also with independent ages, provided by radiocarbon dating of shells and charcoal, and uranium-series dating of travertine.  相似文献   

High-energy inundation events versus long-term coastal processes – room for misinterpretation     

Michaela Spiske  Anna-Marietta Garcia Garcia  Sumiko Tsukamoto  Volkmar Schmidt 《Sedimentology》2020,67(3):1460-1480

Coastal boulder deposits and chevrons are two features whose origin have triggered controversial discussions. Boulders are often used as indicators of past tsunamis and storms, with the former interpretation in many cases preferred due to the clast size. Chevrons, defined as large parabolic sand bodies, were previously attributed to (mega-)tsunami, potentially caused by oceanic impacts, because of their dimensions, height above sea level and alignment of the central axis. This study documents that chevrons along the Quobba coast in Western Australia are parabolic dunes and not related to tsunami inundation; their age is consistent with an arid period at about 3·9 to 2·3 ka when the sea level was 1 to 2 m higher than today. The internal age distribution proves an inland migration. Weakly developed soil horizons represent phases of intermittent dune stabilization and later reactivation. The calculated velocities required for wind transport and the prevailing wind directions are consistent with on-site meteorological parameters. The boulders at Quobba are most likely to be remnants of in situ platform denudation that produces shell hash, coral clasts and boulders. An unknown portion of the boulders was certainly moved by tropical cyclones. A previously proposed tsunami origin is unsustainable because the observed features can be explained by processes other than tsunamis. Boulders were tilted during gravitative platform collapse, standing water caused dissolution of the boulder bottoms, creating ‘pseudo-rockpools’, consequently not applicable as upside-down criteria, and ages of attached encrusting organisms document their colonization at higher sea level and (sub)recent frequent inundation by wave splash during rough seas.  相似文献   

Luminescence dating of lacustrine sediments from Tangra Yumco (southern Tibetan Plateau) using post‐IR IRSL signals from polymineral grains          下载免费PDF全文

Hao Long  Torsten Haberzettl  Sumiko Tsukamoto  Ji Shen  Thomas Kasper  Gerhard Daut  Liping Zhu  Roland Mäusbacher  Manfred Frechen 《Boreas: An International Journal of Quaternary Research》2015,44(1):139-152

Radiocarbon dating of bulk organic matter is the most commonly used method for establishing chronologies of lake sediments for palaeoclimate reconstructions on the Tibetan Plateau. However, this method is likely to be problematic because the dated material often suffers from old carbon contamination. Recently, advances in luminescence‐based chronological techniques have provided new options for dating lacustrine sediments. In the current study, we tested for the first time the applicability of a new post‐IR IRSL (pIRIR) measurement protocol for dating fine‐grained polymineral material from a deep‐lake sediment core from the central part of Tangra Yumco, on the southern Tibetan Plateau. Our results show that: (i) radioactive disequilibria in the uranium decay chain were observed in the studied lake sediments, and thus taken into account for dose rate calculation by using a dynamic modelling approach; (ii) the suitability and robustness of the pIRIR protocol measured at 150°C (pIRIR₁₅₀) for our samples are confirmed by a set of luminescence characteristic tests as well as the agreement with an independent age control; (iii) turbidite deposition partly caused an insufficient resetting of luminescence signals and thus apparent overestimation in luminescence dating; (iv) compared with the luminescence‐based age‐depth model, the ¹⁴C ages of bulk organic matter from the studied core generally yielded an age difference of ～2 ka, which is attributed to hardwater reservoir effects in Tangra Yumco. This study highlights the need for multi‐dating approaches of lake sedimentary archives on the Tibetan Plateau.  相似文献   

Lake level reconstruction of Huangqihai Lake in northern China since MIS 3 based on pulsed optically stimulated luminescence dating          下载免费PDF全文

Jingran Zhang  Sumiko Tsukamoto  Yulian Jia  Manfred Frechen 《第四纪科学杂志》2016,31(3):225-238

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Corrigendum to “The self gravity effect on the orbital stability of Twotinos” [Icarus 212 (2011) 911-919]     

Yusuke Tsukamoto 《Icarus》2011,214(2):782

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Long-term features of drifting and standing non-dipole fields as determined from Holocene palaeomagnetic secular variations     

Chizu Itota  Masayuki Hyodo  Katsumi Yaskawa 《Geophysical Journal International》1997,130(2):390-404

Geomagnetic field motions of Holocene secular variations are investigated using a separation method. The palaeomagnetic secular variations from Britain, North America and Australia have been subjected to maximum-entropy method analyses. Based on the results of spectral analyses, the secular variations are separated by band-pass filters into low-frequency components, generally including the period band 1800-3600 yr, and high-frequency components, generally including the period band 1000-1200 yr. There is an interval, from 4200 to 1700 yr BP, which shows clockwise rotational motions in the low-frequency components of all three sites. Westward drifting of geomagnetic fields may be globally dominant. Swinging or elliptical looping motions constrained to a certain direction were observed in the low-frequency components of the British data. The time duration for the persistence of the swinging motion constrained to a certain direction was 3500 years or so, which could be the lifetime of an oscillating stationary field. The duration of the transitional motion was 1000-1300 years, which may indicate the recurrence time of a stationary field.  相似文献   

Age of glacial and periglacial landforms in northern Hokkaido, Japan, using OSL dating of fine grain quartz     

R. Kondo  S. Tsukamoto  H. Tachibana  Y. Miyairi  Y. Yokoyama 《Quaternary Geochronology》2007,2(1-4):260-265

The timing of glacial advances, periglacial phenomena, and the ages of two marker tephras in northern Hokkaido were estimated by OSL dating. It appears that the glacier of Yamunai 2 stage on Rishiri Island expanded between 24 and 15 ka. In northern Hokkaido, OSL ages indicate ice wedge formation during the period 24–18 ka. These results indicate that both the glacial advance and the development of ice wedges were synchronous phenomena relating to the Last Glacial Maximum.  相似文献   

A psychological effect of having a potentially viable sequestration strategy     

Katsumi Matsumoto 《Carbon balance and management》2006,1(1):1-2

We are pleased to announce the launch of Carbon Balance and Management, a new online open access journal published by BioMed Central.  相似文献