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301.
Kenji Horie Megumi Yamashita Yasutaka Hayasaka Yasuo Katoh Yukiyasu Tsutsumi Aya Katsube Hiroshi Hidaka Hyeoncheol Kim Moonsup Cho 《Precambrian Research》2010
U–Pb zircon geochronology of two Permo-Triassic granites (samples OT-52 and OT-272 with ages of 229 ± 8 Ma and 256 ± 2 Ma, respectively) in the Unazuki area, Hida Metamorphic Belt, southwest Japan, revealed the presence of Eoarchean to Paleoproterozoic inheritance. Inheritance is consistent with both samples showing low zircon saturation temperatures for their bulk compositions. In OT-52, dark in CL, low Th/U zircon domains have a mean 207Pb/206Pb age of 1940 ± 17 Ma, which is consistent with an age of 1937 ± 6 Ma for anatexis in the Precambrian Busan gneiss complex in Korea. Eoarchaean inherited zircons with 207Pb/206Pb ages from ca. 3750 to 3550 Ma are common in OT-272 but are few in OT-52, suggesting a source from rocks with affinities to those in the Anshan area in the northeast China part of the North China Craton. On the other hand, a Hida Metamorphic Belt metasedimentary gneiss into which the granites were intruded contains ca. 1840, 1130, 580, 360, 285 and 250 Ma zircons (Sano et al., 2000). These ages suggest that the Unazuki Mesozoic granites did not originate from proximal Hida Metamorphic Complex rocks, but instead from unrelated rocks obscured at depth. The predominance of Eoarchean to Paleoproterozoic age components, and the marked lack of 900–700 Ma components suggest that the source was the (extended?) fringe of the North China Craton, rather than from Yangtze Craton crust. The Mesozoic evolution of Japan and its linkages to northeast Asia are discussed in the context of these results. 相似文献
302.
Eun-Hee Lee Jaisoo Kim Ji-Young Kim So-Yeon Koo Sang-Dong Lee Kyung-Seok Ko Dong-Chan Ko Byoung-Woo Yum Kyung-Suk Cho 《Environmental Earth Sciences》2010,60(2):371-382
This research has been performed to determine the differences in microbial communities according to physicochemical properties
such as concentrations of volatile aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene (BTEX), dissolved
oxygen (DO), electron acceptors, etc., in oil-contaminated groundwaters at Kyonggi-Do, South Korea. The properties of bacterial
and microbial communities were analyzed by 16S polymerase chain reaction (PCR) denaturing gradient gel electrophoresis (DGGE)
fingerprinting method and community-level physiological profiling (CLPP) using Eco-plate, respectively. Based on the DGGE
fingerprints, the similarities of bacterial community structures were high with similar DO levels, and low with different
DO levels. Whereas the dominant bacterial groups in GW13 (highest BTEX and lowest DO) were acidobacteria, α-proteobacteria,
β-proteobacteria, γ-proteobacteria, δ-proteobacteria, and spirochetes, those in GW7 (highest BTEX and highest DO) were actinobacteria,
α-proteobacteria, β-proteobacteria, γ-proteobacteria, δ-proteobacteria, and sphingobacteria. Based on the CLPP results, the
groundwater samples were roughly divided into three groups: above 4 mg/L in DO (group 1: GW3 and GW7), below 4 mg/L in DO
(group 2: GW8, W1, W2, W3, and BH10), and highly contaminated with BTEX (group 3: GW13). Shannon index showed that the microbial
diversities and equitabilities were higher in shallower aquifer samples. Overall, this study verified that the greatest influencing
factors on microbial/bacterial communities in groundwaters were DO and carbon sources, although BTEX concentration was one
of the major factors. 相似文献
303.
Dust storms on Owens (dry) Lake located 200 milesnortheast of Los Angeles, California, U.S.A., havecaused serious PM10 emission problems. Alaboratory-based experimental study was conducted toinvestigate the efficiency of 'vegetation cover' onthe playa to suppress dust emission rates as part ofa mitigation plan.Erodible lakebed material and field vegetation (saltgrass) taken from Owens (dry) Lake were placed in awind tunnel to simulate near-surface wind flow in theatmospheric boundary layer. Vertical wind-speedprofiles and vertical PM10-concentration profileswere measured over six different levels of surfacevegetation cover. In order to understand the mechanismof aeolian particle transport and dust injection intothe atmosphere, the roughness parameter, z0, thefriction velocity, u*, and the surface dragcoefficient, CD, were carefully determined.An empirical equation was developed to predictPM10 emission rates as a function of wind speedand level of vegetation coverage for Owens (dry) Lake.Although the current results apply only to theeffectiveness of vegetation cover to suppressPM10 emissions at Owens playa, the procedure canbe employed for any arid area or region that mightutilize added vegetation as a mitigation measure. 相似文献
304.
305.
ABSTRACT Rainfall events largely control hydrological processes occurring on and in the ground, but the performance of climate models in reproducing rainfall events has not been investigated enough to guide selection among the models when making hydrological projections. We proposed to compare the durations, intensities, and pause periods, as well as depths of rainfall events when assessing the accuracy of general circulation models (GCMs) in reproducing the hydrological characteristics of observed rainfall. We also compared the sizes of design storm events and the frequency and severity of drought to demonstrate the consequences of GCM selection. The results show that rainfall and extreme hydrological event projections could significantly vary depending on climate model selection and weather stations, suggesting the need for a careful and comprehensive evaluation of GCM in the hydrological analysis of climate change. The proposed methods are expected to help to improve the accuracy of future hydrological projections for water resources planning. 相似文献
306.
SHRIMP U–Pb zircon ages of the Hida metamorphic and plutonic rocks,Japan: Implications for late Paleozoic to Mesozoic tectonics around the Korean Peninsula 下载免费PDF全文
A new U–Pb zircon geochronological study for the Hida metamorphic and plutonic rocks from the Tateyama area in the Hida Mountains of north central Japan is presented. The U–Pb ages of metamorphic zircon grains with inherited/detrital cores in paragneisses suggest that a metamorphic event took place at around 235–250 Ma; the cores yield ages around 275 Ma, 300 Ma, 330 Ma, 1 850 Ma, and 2 650 Ma. New age data, together with geochronological and geological context of the Hida Belt, indicate that a sedimentary protolith of the paragneisses is younger than 275 Ma and was crystallized at around 235–250 Ma. Detrital ages support a model that the Hida Belt was located in the eastern margin of the North China Craton, which provided zircon grains from Paleoproterozoic to Paleozoic rocks and also from Archean and rare Neoproterozoic rocks. Triassic regional metamorphism possibly reflects collision between the North and South China Cratons. 相似文献
307.
We report the first finding of Ediacaran mafic magmatism in northern Victoria Land of the Ross orogen, Antarctica, based on ca. 600–590 Ma magmatic zircon cores in Cambrian eclogites. The mafic magmatism could be either linked to ca. 615–590 Ma incipient convergent margin magmatism in central segment of the Ross orogen, or ca. 600–580 Ma continental rift-related volcanism widespread in eastern Australia. The latter is preferred based on the trace-element compositions distinctive from those of arc-related basalts and the depleted mantle-like Hf isotopic compositions of zircon. Our results suggest dual rifting episodes during both the Ediacaran and Cryogenian (ca. 670–650 Ma) in the East Antarctic margin, correlative with those in eastern Australia. A spatial distribution of coeval rifting and subduction along the Ediacaran margin of East Antarctica is readily accounted for by rift inheritance; the upper- and lower-plate geometry resulting from detachment and transform faulting. 相似文献
308.
Sangheon Yi Chang-Gyun Han Keun-Chang Oh In Sun Seo Dongwook Kim Jaeyoung Lee Min Han Hanwoo Choi Jaesoo Lim Sujeong Park Chang-Pyo Jun Taesop Cho 《第四纪科学杂志》2022,37(1):100-113
We comprehensively analyzed sediments obtained from an archeological excavation. A trench sediment profile of Maedun Cave (MC), South Korea, was analyzed geoarchaeologically. Multi-proxy analyses (palynomorphs, grain size, magnetic susceptibility, animal bones and artifacts) reflected the vegetation, hydroclimate and lives of prehistoric people at Marine Isotope Stage (MIS) 3 (ca. 40–30k cal a bp ) in the early Late Paleolithic. The palynoflora consisted of pollen and non-pollen palynomorphs. Under the air-circulation system in the cave, anemophilous pollen flowed in during the day, whereas waterborne pollen and spores, and freshwater algae, were transported by flooding during the summer monsoon rainy season. Mixed conifer and deciduous broad-leaved forest with an understory of pteridophytes flourished around the north-east central Korean Peninsula during MIS 3. Freshwater algae and grass pollen records may reflect precipitation intensity. It is assumed that they had flowed in during flooding caused by high precipitation during the enhanced East Asian summer monsoon, corresponding to Dansgaard–Oeschger (D/O) events 5 and 8 of δ18O GISP2 and Hulu Cave. The prehistoric people hunted herbivorous animals in the area around MC and sheltered inside it seasonally. They also used the grains of oats growing near the dwelling as a source of food. 相似文献