• 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.

• Ocean and Polar Research
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• v.28 no.4
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• pp.451-457
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• 2006

Hole 1124 of ODP Leg 181 was located in the Rekohu sediment drift off eastern New Zealand in the southwest Pacific Ocean. Mean gain sizes of sortable silt were measured in two drilled cores (1124A and l124B). Chronostratigraphy of core 1124 was correlated with the well-dated nearby core S931, resulting that the age of core 1124 covers the late Pleistocene spanning about MIS (Marine Isotope Stage) 5. Mean grain size of sortable silt seemed to be relatively large during the glacial period, whereas that of the interglacial period was smaller, although several tephra layers contain some coarse-grained pyroclatic particles. The variation in mean grain size of sortable silt in Rekohu sediment drift during the late Pleistocene indicates that the intensity of Deep Western Boundary Current (DWBC) might have been enhanced during the glacial period as a result of increased production of Antarctic Bottom Water (AABW).

• The Korean Journal of Quaternary Research
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• v.17 no.2
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• pp.13-14
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• 2003

It is generally well known that Quaternary is characteristic geologically in terms of glacial and interglacial repeats and their associated unconformity formation. This paper deals with the first finding of the characteristic and significant meaningful unconformity between Holocene and late Pleistocene, which implies submergence and emergence of the tidal sedimentary basin along the western coastal zone of Korea during interglacial stage(IOS-5e) and glacial time(IOS-2). The stratigraphy of intertidal deposits in the Haenam Bay, western coast of Korea shows two depositional sequence units (Unit I of Holocene and Unit II of late Pleistocene) bounded by an erosional surface of disconformity. The disconformity is related to the latest Pleistocene sea-level lowstands (probably during the LGM). The Unit II is interpreted as intertidal deposit showing tidal sedimentary structures and crab burrow ichnology and has two parts (the upper part and the lower part) showing different lithology and character. The upper part of Unit II shows characteristic subaerial exposure features (emergence) and its related lithology. Such subaerially exposed upper part (more or less 4m to 5m in thickness) is characterized by yellow-brownish sediment color, cryoturbat-ed structure, crab burrow ichnofacies and high value of shear strength. Geochemical and clay mineral analyses of the upper part sediments also indicate subaerial exposure and weathering. In particular, very high value of magnetic susceptibility of the upper part in comparison to that of the lower part is interpreted as pedogenetic weathering during the subaerial exposure 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).

• The Korean Journal of Quaternary Research
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• v.12 no.1
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• pp.77-88
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• 1998

한반도의 제4기 지층을 암층서 및 단구층서를 기준으로 전기, 증기 및 후기 플라이 스토신 지층(Ear-ly Middle late Pleistocene Deposits)으로구분할 수 있다. 제 3기와 제4기 의 경계는 고지자기층서 해석에 의하여 한반도에서는 Gauss와 Matuyama chron 경계인 약 2.6Ma를 기준으로 설정할수 있다. 전기 플라이스토신 지층(Early Pleistocene Deposits)은 지형고도상 조구조 운동이 배제된 지역에서는 80m 이하에서의 계곡 사이에서 나타난다. 증 기 플라이스토신 지층(Middle Pleistocene Deposits)은 약0.8Ma부터 약 125ka까지이다. 중기 플라이스토신은 제4기 초깁터 발달하기 시작하였던 주요 계곡들이 현재와 비슷한 형태로 넓 고 깊어지기 시작했던 시기이다. 하천과 해안에는 일련의 단구지형을 잘발달시키지 시작했 고 단구이 형성은 현재보다 해수면이 더 높았던 마지막간빙기까지 계속되었다. 후기 플라이 스토신 지층(late Pleistocene Deposits)은 약 125Ka부터 10Ka까지이며 마지막 간빙기(Last Inter-glacial)와 마지막빙하기(Last Glacial)가 포함된다, 마지막간빙기 동안에는 제 2 하안 및 제 2 해안단구역층이 잘 발달하여 있다 마지막 빙하기 동안에는 해수면의 하강이 극심했 으며 특히 산사면에서 지형경사면을 따라 하부이동된 사면붕적층이 한반도의 전역에 널리 발달했던 시기였다.

• 한국석유지질학회:학술대회논문집
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• spring
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• pp.15-21
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• 1998

Sparker profiles and sediment cores collected from the Korea Strait show a distinct pattern of stacked prograding wedges consisting of three distinct units. These wedges are interpreted as the lowstand deposits formed during glacioeustatic sea-level lowstands. Repeated sea-level falls during late Pleistocene with high sediment discharge from the paleo-Nakdong River system resulted in the formation of thick lowstand wedges.

• Journal of the Korean earth science society
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• v.39 no.1
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• pp.23-45
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• 2018

Moderately diverse, but very abundant trace fossils are found from the Late Pleistocene deposits of Jeju Island, Korea. Vertical I-, Y- and U-shaped domichnia of annelids or decapods are, over 2500, extremely abundant, 3D network domichnia of callianassids are, over 200, very abundant, and small sinuous trails of nematode repichnia are, over 50, abundant in number. Horizontal trails attributable to polychaete or worm-like animals are, less than 50, common, but horizontal spreiten burrows, fish traces and crab trackways are, less than 10, rare in occurrence. Of these trace fossils, Taenidium barretti, Undichna britannica and Undichna unisulca represent the first record from the Pleistocene in Asia. Psilonichnus upsilon is the second record in Asia. Crab trackways probably produced by underwater punting gait of sideway walking crabs may represent the first record in the world. In addition, diverse and very abundant footprints of more than 500 hominids, more than 200 birds and more than 1000 mammals are closely associated with these invertebrate trace fossils. Trace fossil assemblage integrated with sedimentary facies is interpreted to have been formed in the marginal marine foreshore to backshore environment corresponding to the Psilonichnus and Skolithos ichnofacies.

• Journal of the Korean earth science society
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• v.27 no.5
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• pp.579-584
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• 2006

A fossil feather found from the Late Pleistocene sediments of Jeju Island, Korea is described. The sediments deposited in a shallow marine environment yielded numerous footprints of diverse birds and mammals including hominids. A fossil feather well-preserved as a thin white film on the light gray mudstone is part of a vaned flight one. Although the specimen is relatively small in size (10.3 mm long and 9.0 mm wide), a rachis with two flat vanes and nearly parallel curved barbs with numerous proximal and distal barbules are well preserved. The specimen represents the first record of a fossil feather from Korea and is also the first record of feather from the Pleistocene deposits in the world.

• 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.

• Journal of the Korean earth science society
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• v.24 no.8
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• pp.657-667
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• 2003

Deep-drilled core sampling and high-resolution seismic survey were carried out to identify a Holocene-late Pleistocene boundary in Gyeonggi Bay, western coast of Korea. Analysis of core sections revealed the existence of an oxidized and semi-consolidated sediment layer, Iying immediately below a Holocene horizon (Unit I) and being developed at the top of a late Pleistocene deposit (Unit II). The oxidized sedimentary layer (uppermost part of Unit II) is characterized by semi-consolidated, yellowish sediments showing signs of desiccation and alteration such as high N value, low water content, periglacial cryogenic structure, depletion of smectite, and high geochemical weathering index (Ba/Sr ratio). This feature, together with radiocarbon ages, suggests that the layer has formed as a result of prolonged subaerial exposure of Unit II sediments during the late Wisconsin sea-level lowstand, producing a regional unconformity. Such unconformitic-bounding surface corresponds to a prominent near-surface reflector (R), which is observed in seismic profiles obtained across the drilled-core sections in the study area. Consequently, the buried oxidized-sedimentary layer associated with the seismic reflector possibly plays a key horizon for the understanding of late Quaternary environmental changes as well as evidence of the emergence of the Yellow Sea shelf during the late Wisconsin sea-level lowstand.