• Journal of the Korean earth science society
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• v.24 no.1
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• pp.46-60
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• 2003

In Namyang Bay of western Korea, macrotidal-flat deposits are divisible into three late Quaternary units: Unit M1 of upper marine mud, Unit T1 of middle siderite-bearing terrestrial clay, and Unit M2 of lower marine mud. Unit M1 represents typical Holocene intertidal mudflat deposits, showing a coarsening-upward textural trend. It probably resulted from the continual retrogradation of tidal flat during the mid-to-late Holocene sea-level rise. Reddish brown-color Unit T1 consists of homogeneous clay with abundant freshwater siderite grains and plant remains. Unit T1 is clearly separated from the overlying Unit M1 by a sharp lithologic boundary. Radiocarbon age, siderite grains and lithologic features indicate that Unit T1 is originated from freshwater bog or swamp deposition infilling the localized topographic lows during the early Holocene age. Overlain unconformably by early Holocene swamp clay, Unit M2 is orange to yellow in color and mottled, suggesting significant degree of weathering during the sea-level lowstand. Such subaerial oxidation is confirmed in the vertical profiles of geotechnical properties, clay mineral assemblages and magnetic susceptibility. Unit M2 appears to be correlated with the upper part of the late Pleistocene tidal deposits developed along the western Korean coast. The sedimentary succession of the Namyang-Bay tidal-flat deposit provides stratigraphic information for the Holocene-late Pleistocene unconformity and also permits an assessment of the preservation potential of the late Pleistocene marginal marine deposit along the western coast of Korea.

• Journal of the Korean Geographical Society
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• v.46 no.4
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• pp.414-425
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• 2011

The aim of this research is to infer paleovegetation and paleoclimate in the Hwajeon archeological site of Gwangju city during mid-Holocene through the analysis of pollen, waterlogged woods, and sediments. Between 8200 ~ 6800 years ago, relatively dry climate resulted in a weakened dominance of oak and high diversity of tree genus. During the Holocene climatic optimum period (6800 ~ 5900 years ago), oak forests expanded while wetland areas diminished as warm/humid climate intensified. Between 5900 ~ 4700 years ago, the entire forest area as well as oak climax forests was reduced due to a relatively cool/dry climate. However at the end of this period, oak forests expanded since a favorable climate condition temporarily resumed. Lastly, between 4700 ~ 3300 years ago, oaks dominated but alders were weakened. The density of forest was low because of a relatively dry climate in this period.

• The Korean Journal of Quaternary Research
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• v.22 no.2
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• pp.6-11
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• 2008

Vegetation change reconstructed by pollen analysis is effective to clarify natural conditions such as climate and soil as well as intensity of human activity. Pollen analysis in Korea is difficult to obtain peaty soil sedimented by low relief geomorphollogically and formation age is usually confined to obtain information during young Holocene as well as little absolute age data. Isopollen map was constructed in order to analyze the change of vegetation environment time-spatially during Holocene based on the 30 data with age dated from 78 results from pollen analysis in Korea. The indicatives for vegetation environment were the main trees in Korea such as Alnus, Pinus, Quercus and AP/NAP during the periods of 6,000 y.BP, 4,000 y.BP, 3,000 y.BP, 2,000 y.BP, 1,000 y.BP. As a result, the regional time-spatial patterns of vegetation distribution appeared clearly on the isopollen map. The dominant vegetation stage was repeated in the different pattern e.g. the dominance between Alnus and Quercus at West Coast and between Pinus and Quercus at East Coast competitively.

• Journal of the korean society of oceanography
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• v.32 no.3
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• pp.138-144
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• 1997

The tidal deposits in the Haenam Bay, southwest coast of Korea, are stratigraphically divided at least into two units (Unit I of Holocene and Unit II of late Pleistocene) based on the obtained vibracoring sediments. In Unit I, clay minerals of illite, chlorite, kaolinite and smectite are observed as similar to those of the other modern tidal deposits. Of note, however, is the absence of smectite and chlorite in the upper part of Unit II compared with the clay mineral compositions of Unit I. It is concluded that the subaerial weathering and diagenetic effects rather than depositional processes are responsible for the positive and characteristic differences in clay mineral compositions between two units, that is, the upper part of Unit II was exposed subaerially and weathered diagenetically prior to the late Holocene transgression. Therefore, the bounding relationship between Unit I and Unit II is unconformable.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.2
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• pp.71-80
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• 2001

To understand paleoceanographic environmental changes in the Esat Sea during the transitional period between Holocene and last glacial maximum, geochemical high resolution study was conducted by using a piston core(95PC-1) samples collected from the southernmost part of the Ulleung Basin. Geochemical results reveal that major distinctive paleoceanographic variations in transitional period are prominent. Major elemental concentrations show distinctive variations between glacial and Holocene suggesting changes in sediment supply. $TiO_2/Al_2O_3$ ratio of the sediment indicates different sediment composition between Holocene and glacial period. The content of total organic carbon ranging from 0.5% to 4% during transitional period. These vslues showed 2-4 times and two times higher than those of last glacial and Holocene, respectively. The C/N ratios deduced from organic matters exceed10 during transitional period suggesting terrigenous organic matter are supplied from continent, especially during last glacial maximum. Carbonate contents are relatively stable during Holocene and last glacial maximum with gradual decrease during glacial period with high fluctuation during transitional period. The variations of chemical index of weathering (CIW) also show a distinctive variation between glacial and Holocene, which is coincident with those of carbonate and organic carbon. The grain size distribution indicates that the difference content of silt fraction during Holocene and glacial period is closely related with climatic effect during glacial period. Therefore geochemical differences in sediment composition between Holocene and last glacial maximum is thought to be related to paleoceanographic, sea-level change and local paleoclimatic changes.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.1 no.2
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• pp.59-72
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• 1996

The stratigraphy of the Gomso-Bay tidal flat consists of basement, preHolocene oxidized unit, and Holocene tidal sequence in ascending order. The oxidized unit is a yellowish brown stiff mud of the last stadial (or subglacial) stage before 12,000 yr B.P. This yellowish brown preHolocene unit does not contain any marine fossils, but contains plant roots, plant fragments, and also vertical and horizontal microfractures indicating soil-formation when exposed. It is regarded as interfluve deposits. The Holocene tidal sequence is composed of lower mud facies (upper-flat muds), upper sand and muddy sand facies (middle to lower-flat sands). This coarsening-upward and retrograding pattern of Holocene tidal deposits reflects a Holocene sea-level rise. The plots of $\^$14/C-age versus depth of dated samples (peats and shells) show that the sea level of 7,000 yr B.P. was located about 6.5 m below the present mean sea level, and the sea levels of 4,000 yr B.P. and 2,000 yr B.P. were also situated about 3 m and 2.5 m below the present mean sea level, respectively.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.7 no.1
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• pp.32-42
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• 2002

The late Quaternary deposit of Cheonsu Bay, up to 20 m in thickness above the Jurassic granite basement, consists of two sedimentary units: an upper Holocene mud and sandy mud deposit (Unit M1), and a lower late Pleistocene sand and mud deposit (Unit M2; 'Kanweoldo Deposit&apos). Unit M1 is a typical Holocene tidal-flat deposit of Cheonsu Bay, showing a coarsening upward, retrogradational facies trend. This retrograding facies trend is probably due to a relative low sedimentation rate during Holocene transgression. Overlain unconformably by Unit M1, Unit M2 deposit reaches up to 14 m in thickness and is mainly composed of muddy sediment with yellow to gray color. This unit is characterized by a variety of tide-influenced signatures such as rhythmic bedding, flaser bedding, crab burrow fossil, marine dinoflagellate assemblage and authigenic glauconite mineral, indicating very similar depositional environment to those of Unit M1 deposit. It suggests that Unit M2 was probably accumulated under the tidal-flat environment during a pre-Holocene sea-level highstand. In particular, the uppermost 3-4 m of Unit M2 appears to have undergone subaerial exposure and subsequent weathering during the sea-level lowstand after deposition. Therefore, stratigraphic unconformity between Holocene and late Pleistocene sediments is highlighted by the desiccated and weathered surface of Unit M2.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.2 no.1
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• pp.8-13
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• 1997

The Holocene mud deposits in the southeastern innershelf of the Korean Peninsula were studied using the shallow seismic reflection profiles coupled with sediment sampling. The Holocene mud deposits are developed as a belt in the innershelf area from the mouth of the Nakdong River to off Pohang along the coastline. The surficial sediments in the study area gradually become finer and well sorted from south to north. The seismic facies in the Holocene sequence change northward from parallel reflectors in the mouth of the Nakdong River and northeastward prograding reflectors in the southern part off Ulsan to transparent layer in the nearshore off Ulsan to Pohang. The regional difference of seismic facies indicates that the Holocene sediment characters are varied with localities. By combining the surficial sediments properties with seismic facies patterns, the suspended sediments mostly supplied from the Nakdong River may be transported northward along the shore by the north-flowing Tsushima warm current. The Holocene mud sequence overlying the ravinement surface which is produced by erosion of underlying sediments during a rapid transgression can be interpreted as the highstand system tracts probably formed during the highstand of sea level similar to the present-day sea level.

• Journal of The Geomorphological Association of Korea
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• v.17 no.2
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• pp.87-98
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• 2010

There have been growing concerns for the sea level rise due to global warming in recent years. Sea level rise is a serious problem to densely populated coastal areas, because it may affect the coastal landforms to be damaged. Especially coastal sand deposits like coastal dunes are more sensitive than the other coastal landforms. In this paper, Ground Penetrating Radar (GPR) and Optically Stimulated Luminescence (OSL) dating method were used to identify the Holocene geomorphic changes of coastal dune field in Shinduri located at the western coast. The main results in this study that are the dunefield in the study area may have begun to form at around 6.8 ka and it has grown seaward thereafter. Then, dunefield appears to have extensively developed since 3.7 ka. This result, together with previous works on the sea level and climatic changes in the western coast of Korea suggest that the dunefield has been affected by the sea level regression since the Holocene high stand in the Holocene at around 6 ka and climatic change from warm and humid to cold and dry conditions occurred at 4.5 ka.

• Proceedings of the Korean Quaternary Association Conference
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• 2003.05a
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• pp.39-40
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• 2003