• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.876-881
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• 2006

This study was carried out to understand depositional environment and genesis of clayey soils that distributed in the Dongup area. On the basis of detailed observation and description on mineralogy, geochemical composition, geophysical properties, paleontological analysis of cored sediments, three sedimentary unit have been distinguished. From bottom to top, they are early Holocene freshwater muddy deposit(Unit I, fluvial swamp), late Holocene silt and muddy deposit(Unit II, alluvial deposit), late Holocene muddy deposit(Unit III, fluvial swamp). Unit II is divided into three part: the lower part-unweathered massive silt and muddy deposit, middle part-weathered layered slit and muddy deposit and upper part-weathered massive muddy deposit.

• Journal of The Geomorphological Association of Korea
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• v.26 no.1
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• pp.27-40
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• 2019

This study tries to reveal source areas of fluvial terrace deposits in Danyang and Geum River basins located in the northern and southern parts of the Sobaek Mountains, respectively, through geochemistry. The samples analyzed in this study show different grain size properties and can be grouped into the coarse, medium and fine samples. Grain size properties suggest that the coarse samples are typically fluvial deposits and geochemistry from the coarse samples is also similar to that from the bedrocks within the basins. The fine samples show geochemical properties different from the bedrocks and similar to loess deposits in Korea. However, different geochemical concentrations among the fine samples can be also recognized, indicating mixtures of loess materials with weathering products of the bedrocks. One sample among the medium samples is considered as fluvial deposit due to geochemical similarity to the bedrocks, while geochemistry from another sample among the medium samples indicates that loess materials were mixed with more abundant weathering products of the bedrocks than those in the fine samples.

• Journal of The Geomorphological Association of Korea
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• v.18 no.3
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• pp.37-51
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• 2011

Geomorphic changes and sedimentary changes are investigated by sediment analysis from estuarine tidal flat, Mosan Bay Estuary, which is a tide-dominated and rias estuary. Sediments separatedly deposited during the early Holocene and the late Holocene. There are unconformities between the early Holocene sediment unit and the late Holocene sediment unit. Developments of these unconformities were related with fluctuated sea level change during the mid Holocene. Three deposit zones are spatially classified, which are named "intermittent tide channel deposit zone"(A1, B1, D3), "flood-dominated deposit zone"(A3, B3, C1, C3), and "fluvial sediment deposit zone"(A2, B2). This classification is explained by three main effects; laterally restricted migration of a tidal channel, diffract flood effect and settling lag effect, and fluvial induced reworking. These effects are deserved as main factors which have formed estuarine geomorphology in tidedominated and rias estuary. This study suggests research directions in reconstructing estuarine geomorphic and sedimentary change in west coast of Korea. Furthermore, it gives useful data for making a "land-ocean interaction" model for west coast of Korea.

• Journal of the Korean earth science society
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• v.26 no.8
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• pp.828-835
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• 2005

The purpose of this study is to clarify the landform development of fluvial terrace and the soil characteristics occurring on the terrace deposit. In order to achieve the purpose, the characteristics of soil profiles, the physic-chemical properties of soils that are developed on terrace deposits and X-ray diffraction analysis of clay were investigated. The horizon of Al in the high fluvial surface is silt clay loam of red (2YR 4/6). The soil structure is a developed granular structure. The horizon of B1 is silt clay reddish-brown (2.5YR 4/6). The soil structure is a medium subangular blocky structure. This red soil structure is made on heavy textured and compactly packed parent materials of high terrace sediments and usually has A-B-C profile. In most cases, clay accumulations in B-horizon and clay cutans on ped surfaces are observed, which mean the formation of agrillic horizon. As the result of this study, soils derived from fluvial terrace deposits on high fluvial surfaces are considered paleo-red soil which were developed by pedogenese-strong desilicification and rubefaction and strong leaching of bases- under warmer bio-climatic condition during in the old Pleistocene period.

• The Korean Journal of Quaternary Research
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• v.13 no.1
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• pp.79-89
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• 1999

Three deep borings to obtain vertical continuous samples including weathered basement soils (KP-1, KP-2 and KP-3) were carried out in the reclaimed Kimpo tidal flat with purposes to establish late Quaternary stratigraphy. On the basis of detailed observations and descriptions on color, sedimentary structure and textural composition of cored sediments, four lithostratigraphic units are classified. From the stratigraphic top to bottom, they are Holocene tidal sand and muddy deposit (Unit I), early Holocene freshwater marsh muddy deposit (Unit II), late Pleistocene tidal sand and muddy deposit (Unit III) and late Pleistocene basal fluvial gravel deposit (Unit IV). In particular, Unit III is divided into two parts: the upper part-weathered and cryoturbated part during the Last Glacial Maximum (Unit III-a) and the lower part-unweathered tidal sand and muddy deposit (Unit III-b).

• Economic and Environmental Geology
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• v.39 no.2 s.177
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• pp.191-212
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• 2006

Placer gold deposits is mainly distributed in the Takaoi area. The alluvium is unconsolidated or semiconsolidated deposit consisting of gravel, sand, and soil beds in ascending order. They unconformably overlies the Carboniferous-Permian schist and Cretaceous granodiorite substratum. Based on detailed facies analysis, the alluvium can be interpreted as a typical fluvial deposits containing gravel and sand beds of channel-fill unit and soil deposit of floodplain. Gold grains are included mainly in the gravel bed and vein quartz is only contained gold among all kinds of gravels. These features indicates that the source rock of the gold grain is vein quartz and gold grains are separated from vein quartz during transport and abrasion. The reserves of gold in this area reach to at least 792 kg.

• Environmental Engineering Research
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• v.18 no.3
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• pp.129-137
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• 2013

The infiltration of rainwater into the surface soil is highly dependent on hydraulic variables, such as the infiltration rate, capillary fringe, moisture content, and unsaturated/saturated hydraulic conductivity. This study estimates the hydraulic conductivity (K) of fluvial deposits at three sites on the right and left banks of Nakdong River in Gyeongbuk Province, South Korea, including the Gumi, Waegwan, and Seongju bridge sites. The K values of 80 samples from 13 boreholes were estimated by using six grain-size methods (Hazen, Slichter, Kozeny, Beyer, Sauerbrei, and Pavchich formulae). The Beyer, Hazen, and Slichter methods showed a better relationship with K values along with an effective grain size than did the other three methods. The grain-size, pumping test, and slug test analyses resulted in different K values, but with similar K values in the grain-size analysis and pumping test. The lower K values of the slug test represent the uppermost fine sand layer.

• Proceedings of the KSEEG Conference
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• 2003.04a
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• pp.24-24
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• 2003

The Eunsan gold mine, together with similar nearby prospects, is situated near the centre of the ‘Wusuyeong’ 1:50000 Scale Geological Quadrangle, an area largely underlain by a thick sequence of non-marine Cretaceous strata. The sequence, several kilometres thick, comprises basaltic and andesitic lavas and tuffs, intercalated with fluvial and lacustrine sediments, passing upwards into a further thick volcanic sequence of predominantly dacitic and rhyolitic composition. (omitted)

• Journal of The Geomorphological Association of Korea
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• v.26 no.4
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• pp.21-31
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• 2019

Timing of terrace formation is a key information for understanding the evolution of fluvial systems. In particular, dating strath terrace (i.e. timing of terrace abandonment) is more difficult than depositional terrace that is conventionally constrained by radiocarbon, OSL and other dating methods targeting samples within terrace deposit. Surface exposure dating utilizing cosmogenic ¹⁰Be provides more reliability because it can be applied directly to the surface of a fluvial terrace. Thus, this method has been increasingly used for alluvial deposits. As well as other geomorphic surfaces over the last decades. Some inherent conditions, however, such as post-depositional ¹⁰Be concentration (i.e. inheritance), surface erosion rate, and density change challenge the application of cosmogenic ¹⁰Be to depositional terrace surface against simple bedrock surface. Here we present the first application of ¹⁰Be depth profile dating to a thin-gravel covered strath terrace in Korea. Monte Carlo simulation (MCS) helped us in better constraining the timing of abandonment of the strath terrace, since which its surface stochastically denuded with time, causing unexpected change of ¹⁰Be production with depth. The age of the strath terrace estimated by MCS was 109 ka, ~4% older than the one (104 ka) calculated by simple depth profile dating, which yielded the best-fit surface erosion rate of 2.1 mm/ka. Our study demonstrates that the application of ¹⁰Be depth profile dating of strath terrace using MCS is more robust and reliable because it considers post-depositional change of initial conditions such as erosion rate.

• The Korean Journal of Quaternary Research
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• v.14 no.2
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• pp.125-135
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• 2000

The late Quaternary stratigraphy and basal unconformity (nonconformity) of the intertidal deposits (upper tidal flat) in the Banweol tidal basin in the Kyunggi Bay, west coast of Korea has been investigated and established. The Unit I (middle to late Holocene upper intertidal deposit) and Unit II (pre-Holocene fluvial to alluvial deposit) in descending order are classified and interpreted. The basement rocks of the Banweol tidal basin is dominantly preCambrian metamorphic rocks on which Unit II is overlying unconformably. In short, the late Quaternary stratigraphy and unconformity of the Banweol tidal flat deposits are established and interpreted in terms of sedimentology and sea-level fluctuation history during late Quaternary.