Characterization of alluvium soil using geophysical and sounding methods     

Chung-Hwa Park  Ji-Hwan Byun  Kyung-Sik Won  Hyun-Tae Cho 《Marine Georesources & Geotechnology》2017,35(1):127-135

The alluvial deposits are highly heterogeneous and thus special techniques for investigating the subsurface have been required to obtain high quality data. The objective of this study is to apply two geophysical methods to alluvial deposits: a seismic survey method and the electrical resistivity method. The one-dimensional sounding method known as the standard penetration test is also applied to investigate subsurface properties and to compare these results with those measured by the geophysical methods. In seismic survey method, the seismic impulse source system shotgun is used to strongly propagate the elastic wave through the soil. The nonpolarizable electrode is selected to obtain the most reliable result by reducing the contact resistance. The application test is performed at Nakdong River in the southern part of Korean Peninsula where the area consists of alluvial deposits. The four profiles are selected for conducting the geophysical methods and the ranges of profiles are 115 ～ 205 m with interval distance of 5 m. The six one-dimensional soundings are performed in the intersection of geophysical profiles. Even though the measured results based on the geophysical method and one-dimensional sounding show slight difference, every result is applied to estimate subsurface characterization as the complementary data.  相似文献   

Quaternary Crustal Deformation in the Southeastern Part of the Korean Peninsula     

Bong Joo Lee  Chung-Ryul Ryoo  Deung-Lyong Cho  Sung-Ja Choi  Ueechan Chwae   《Gondwana Research》1999,2(4):578-582

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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

Yutaka Takahashi  Deung‐Lyong Cho  Jianren Mao  Xilin Zhao  Keewook Yi 《Island Arc》2018,27(1)

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   

Evaluating the performance of climate models in reproducing the hydrological characteristics of rainfall events     

Jung-Hun Song  Satbyeol Shin  Jaepil Cho  Rajendra Paudel  Yogesh P. Khare 《水文科学杂志》2020,65(9):1490-1511

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   

Ediacaran mafic magmatism recorded in Cambrian eclogites of the Ross orogen,Antarctica: Implications for the Neoproterozoic rifting episodes along the Pacific-Gondwana margin     

Taehwan Kim  Yoonsup Kim  Wonseok Cheong  Moonsup Cho  Jong Ik Lee 《地学学报》2023,35(1):32-40

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   

A preliminary study of natural environmental change and its impact on early Late Paleolithic people in the northeast central Korean Peninsula during Marine Istope Stage 3 (40–30k cal a bp)     

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