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Itaru Yamashita Adichat Surinkum Yutaka Wada Makoto Fujihara Masao Yokoyama Haider Zaman Yo-ichiro Otofuji 《Journal of Asian Earth Sciences》2011,40(3):784-796
Jurassic to Cretaceous red sandstones were sampled at 33 sites from the Khlong Min and Lam Thap formations of the Trang Syncline (7.6°N, 99.6°E), the Peninsular Thailand. Rock magnetic experiments generally revealed hematite as a carrier of natural remanent magnetization. Stepwise thermal demagnetization isolates remanent components with unblocking temperatures of 620–690 °C. An easterly deflected declination (D = 31.1°, I = 12.2°, α95 = 13.9°, N = 9, in stratigraphic coordinates) is observed as pre-folding remanent magnetization from North Trang Syncline, whereas westerly deflected declination (D = 342.8°, I = 22.3°, α95 = 12.7°, N = 13 in geographic coordinates) appears in the post-folding remanent magnetization from West Trang Syncline. These observations suggest an occurrence of two opposite tectonic rotations in the Trang area, which as a part of Thai–Malay Peninsula received clockwise rotation after Jurassic together with Shan-Thai and Indochina blocks. Between the Late Cretaceous and Middle Miocene, this area as a part of southern Sundaland Block experienced up to 24.5° ± 11.5° counter-clockwise rotation with respect to South China Block. This post-Cretaceous tectonic rotation in Trang area is considered as a part of large scale counter-clockwise rotation experienced by the southern Sundaland Block (including the Peninsular Malaysia, Borneo and south Sulawesi areas) as a result of Australian Plate collision with southeast Asia. Within the framework of Sundaland Block, the northern boundary of counter-clockwise rotated zone lies between the Trang area and the Khorat Basin. 相似文献
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CuiHua Huang Fei Peng Itaru Shibata Jun Luo Xian Xue Kinya Akashi Atsushi Tsunekawa Tao Wang 《寒旱区科学》2019,11(1):81-92
Biological soil crusts(BSCs) play important roles in the carbon(C) balance in arid regions. Net C balance of BSCs is strongly dependent on rainfall and consequent activation of microbes in the BSCs. The compensation-rainfall size for BSCs(the minimum rainfall amount for a positive net C balance) is assumed to be different with BSCs of different developmental stages. A field experiment with simulated rainfall amount(SRA) of 0, 1, 5, 10, 20, and 40 mm was conducted to examine the C fluxes and compensation-rainfall size of BSCs in different parts of fixed dunes in the ecotone between the Badain Jaran Desert and the Minqin Oasis. We found algae-lichen crust on the interdunes and crest, algae crust on the leeward side, and lichen-moss crust on the windward. Even a small rainfall(1 mm) can activate both photosynthesis and respiration of all types of BSCs. The gross ecosystem production, ecosystem respiration, and net ecosystem exchange were significantly affected by SRA, hours after the simulated rainfall, position on a dune, and their interactions. The rapid activation of photosynthesis provides a C source and therefore could be responsible for the increase of C efflux after each rewetting. C-uptake and-emission capacity of all the BSCs positively correlated with rainfall size, with the lowest C fluxes on the leeward side. The compensation rainfall for a net C uptake was 3.80, 15.54, 8.62, and 1.88 mm for BSCs on the interdunes, the leeward side, the crest, and the windward side, respectively. The whole dune started to show a net C uptake with an SRA of 5 mm and maximized with an SRA of about 30 mm. The compensation-rainfall size is negatively correlated with chlorophyll content. Our results suggest that BSCs will be favored in terms of C balance, and sand dune stabilization could be sustained with an increasing frequency of 5-10 mm rainfall events in the desert-oasis transitional zone.- 相似文献
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The paleo-hydrography in the Japan Sea called a “mini-Ocean” was reconstructed based on the high-resolution analysis of diatom assemblages over the period of 150,000 yr. The decrease of diatom fertilization in the Japan Sea, when it was isolated from surrounding seas due to the drop of sea-level during the glacial to stadial phase, resulted in dissolution and/or extremely low diatom production in the northern cores in the subarctic water-masses. The annual Td′-derived paleo-SSTs (°C) were controlled by the fluctuations of 2-kyr and 4-kyr periods at intervals of 20 kyr and 40 kyr over the last 160 kyr BP, respectively. A 23-kyr cycle is recognized during the periods from 140 ka to 100 ka, according to the Wavelet analysis. After temperature and sea-level increased both at 133–128 ka, 60–53 ka and 15–10 ka, oceanic warm-water diatom species predominated at 127–119 ka and after 9 cal ka in the interstadial phase. At 21.3–16.9 ka and 12.9–9.8 ka, sea-level and salinity increased as the transgression developed. At 10.0–7.0 ka, the oceanic association shifted from cold-water species in the stadial period to warm-water ones in the interstadial phase. The fluctuations of Td′ derived-SSTs (°C) on century to millennial time-scales during the Holocene are well correlated with abrupt climatic events that different paleoclimatic proxies record in many regions of the Northern Hemisphere. 相似文献
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Yasuhiko Okada Sonoyo Mukai Itaru Sano 《Journal of the Indian Society of Remote Sensing》2002,30(1-2):81-86
Ocean color analysis and aerosol retrieval in coastal regions are made difficult by water turbidity. An algorithm has been proposed which uses the data at a blue wavelength instead of those in near-infrared wavelengths for the aerosol retrieval. The quasi-homogeneous effects are assumed for the correction of water leaving radiance with soil particles at 0.412 μm. The proposed algorithm is examined using SeaWiFS data on December 24, 2000 around India. Over the coastal waters, extremely large values of optical thickness are extracted from the operational SeaWiFS algorithm, whereas our proposed algorithm produces a smooth transition in values of optical thickness from the turbid waters to the surrounding regions. 相似文献
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Aerosol properties and air pollutants over an urban area 总被引：2，自引：0，他引：2
For a better understanding of urban aerosols, sun/sky photometry has been undertaken at the Kinki University campus in Higashi-Osaka as a NASA/AERONET station since 2002. A new instrument, the SPM-613D (Kimoto Electric), has been taking measurements at the same site since March 15, 2004. The relationship between aerosol properties obtained from radiometry with AERONET and the SPM measurements is examined. It is found that there is a linear correlation between SPM concentrations and aerosol properties, which indicates that aerosol characteristics can be estimated from SPM data, and vice versa.It is also shown that the air quality of the Higashi-Osaka site is poor due to not only the anthropogenic particles by local emissions, such as diesel vehicles and chemical industries, but also due to the dust particles coming from continental desert areas by large scale climatic conditions. 相似文献
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Youhei Kawamura Ashraf M. Dewan Bert Veenendaal Masahiro Hayashi Takeshi Shibuya Itaru Kitahara 《International Journal of Digital Earth》2014,7(4):279-293
Communications network damage resulting from a large disaster causes difficulties in the ability to rapidly understand the current situation and thus make appropriate decisions towards mitigating problems, such as where to send and dispense emergency supplies. The research outlined in this paper focuses on the rapid construction of a network after a disaster occurs. This study suggests ZigBee and geographic information systems (GIS) technologies to resolve these problems and provide an effective communication system. The experimental results of the ZigBee network system are presented, examples are provided of the mapping and analysis undertaken using GIS for the disaster-stricken area of Tsukuba City, Japan, and the communications node arrangements are determined for this region. These results demonstrate the effectiveness of establishing such a communications system for supporting efforts to relieve disaster-damaged areas. 相似文献
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