• Title/Summary/Keyword: Holocene environmental change

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Holocene paleoenvironmental changes in the Lake Khuvsgul, Northern Mongolia (몽골 북부 흡수굴호의 홀로세 동안의 고환경 변화)

  • Orkhonselenge, A.;Kashiwaya, K.;Ochiai, S.;Krivonogov, S.K.;Nakamura, T.
    • The Korean Journal of Quaternary Research
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    • v.22 no.1
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    • pp.28-36
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    • 2008
  • The present study has focused on the environmental changes and evidences for sedimentation in the Lake Khuvsgul catchment during the Holocene period, inferred from short core sediment (BO03) from the eastern shore of Borsog Bay, which were analyzed in order to review records of the Holocene climatic evolution and Holocene history in Northern Mongolia. For the purpose of reconstruction of natural phenomenon that occurred in the lake catchment system during the Holocene, physical and chemical properties including HCl-soluble material, biogenic silica, organic matter and grain size distribution of minerals in the core sediments have been analyzed in this study. The vertical variations in composition for these properties show distinctly that five lines of paleoenvironmental evidence occurred in the lake catchment during the Holocene. A modified age model resulting from AMS carbon dating for the BO03 core sediment shows timings of these environmental events at 9.5 Kyr BP, 8.0 Kyr BP, 5.6 Kyr BP and 3.2 Kyr BP, respectively. Paleoenvironmental changes in the Lake Khuvsgul catchment system during the Holocene highlight distinctive features of the hydrological regime and geomorphologic evolution in the lake catchment due to regional landscape and global climatic changes corresponding with the Holocene optimum and thermal optimum. In particular, the change of hydrologic regime based on the sedimentological evidence has been caused by not only overland flow due to melting water, but also base flow due to thick permafrost around Khuvsgul region.

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The Environmental Change of Korea based on the Isopollen Map during the Holocene

  • Yoon, Soon-Ock
    • 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.

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The Environmental Change and Geomorphic Development of Unsan Alluvial Plain in Kangreung City during the Late Holocene (강릉 운산충적평야의 홀로세 후기의 환경변화와 지형발달)

  • 윤순옥
    • Journal of the Korean Geographical Society
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    • v.33 no.2
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    • pp.127-142
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    • 1998
  • Unsan alluvial plain is the backmarsh of Seomseokcheon which is a river originated from Chilseongdae(954m) on Mts Taeback, flowing into Donghae in southern Kangreung City, Kangwon Province. The vegetation change, geomorphic develoopment and depositional environment during the late Holocene have been investigated, using the methods such as boring, pollen analysis and radiocarbon dating. Because the deposits fo the study area are mainly consisted of peat and paety sand, they contained many pollen fossils. The peat layer has been sedimented since the high sea-level periods, 3,200 y. BP, and the records of vegetation change until now has well preserved here. According to archeological researches and the results of pollen analysis in east coast of Korea, it is supposed that the prehistoric rice farming in this area has begun since ca. 1,800 y. BP.

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The Change of the Depositional Environment on Dodaecheon River Basin during the Middle Holocene (Holocene 中期에 있어서 道垈川流域의 堆積 環境 變化)

  • Hwang, Sang-Ill;Yoon, Soon-Ock;Jo, Wha-Ryong
    • Journal of the Korean Geographical Society
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    • v.32 no.4
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    • pp.403-420
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    • 1997
  • Dodaecheon is a small river flowing into Asan Bay which is located in the middle part of the West Coast of the Korean Penninsula. We have investigated the change of depositional environment in Dodaecheon river basin during the middle Holocene. In the course of the research, the methods such as boring, radiocarbon dating, diatom and pollen analysis were employed. The Holocene deposits of the studied area are consisted of peat and gray silt layers, and contain many plooen and diatom fossils. Based on the results of diatom and pollen analysis, we conclude that the gray silt layers were sedimented owing to the transgression in the middle Holocene, and the peat layers by the regression or stabilzation of the sea level. The shoreline in the Post Glacial Age reached to the rivemouth of Dodaecheon at ca. 7,000 years before present(y. BP) and at that time the high tide sea-level(mean high water level of spring tide) rose to ca. 3m above present mean sea-level(m.a.s.l.). Since then to ca. 6,000y. BP, the high tide sea-level arrived to ca. 5m above present mean sea level further repeating minor transgressions and regressions. The peat layers of the coastal lowland of the West Coast were formed by the sea level fluctuations from 7,000 y. BP to 3,000 y. BP, and they were distributed 2 to 6 meters higher than the mean sea level of the present day. Most of them sedimented due to the high tide level are older and higher than those of the East Coast which were formed at the swale in the low tidal range environment.

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The Holocene Depositonal Environment and Sea-Level Change at Ilsan Area (일산충적평야의 홀로세 퇴적환경변화와 해면변동)

  • 황상일
    • Journal of the Korean Geographical Society
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    • v.33 no.2
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    • pp.143-163
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    • 1998
  • In order to clarify the depositional environment and sea-level change at Ilsan area including Gawaji and Saemal valley plains, which is located at the right side in downstream of the Han River, boring data, radiocabon dating and diatom analysis were comprehensively investigated. As a result, the palaeogeographies fo this area altered by the transgressions and regressions after 7,000 y. BP could be restored. The high tide sea-level(mean high water level of spring tide) was arrived ca. 7,000y. BP at the valley plain and risen to ca. 5.5m at ca. 5000y. BP. Since then, the sea-level was kept up the same level to ca. 3,200 BP. The descended sea-level to ca. 2,300 BP was risen up to ca. 5.8m in ca. 1,800 y. BP. It is presumed that such a sea-level change as well as the different sediments in quantity supplied from the river basin of the valley plain could be effected to change diversely the depositional environment of the study area and eventually to the prehistoric human life.

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Last Glacial Maximum-Holocene Variability in Geochemical Records of a Core Sediment from the Southern Part of the Ulleung Basin, East Sea: Implications for Paleoceanographic Changes (동해 울릉분지 남단 주상퇴적물에 대한 최종빙기-홀로세간의 지화학적 기록 변화: 고해양환경 변화)

  • Huh, Sik;Han, Sang-Joon;Hyun, Sang-Min
    • 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.

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The Change of Vegetation Environment since middle-late Holocene in the lower reaches of Taehwa River, Taehwa-dong, Ulsan-si, Korea (울산 태화강 하류 태화동 홀로세 중·후기 식생환경 변화)

  • Kim, HyeRyung;Yoon, Soon-Ock;Hwang, Sangill
    • Journal of The Geomorphological Association of Korea
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    • v.23 no.2
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    • pp.1-13
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    • 2016
  • This study analyzed pollen compositions in archaeological site on alluvial plain of Taehwa River, Taehwa-dong, Ulsan-si vegetational and environmental change during 6,200~3,000 yr BP. The results consist upward of Pollen Zone I (Inner Bay environment), Pollen Zone II (Quercus-Alnus stage) and Pollen Zone III (Alnus stage). The pollen grains of Fagopyrum and reddish gray silty horizon including artifacts of the Bronze Age suggest that there was cultivation on dry-field around the study site, although it is not sure that there was paddy-field cultivation.

Quantitative Reconstruction of Sea Level Change Using Diatom-Based Transfer Function at Sinduk-ri, Gochang-Gun Since the Middle Holocene (규조기반 전이함수를 활용한 Holocene 중기 이후 고창군 신덕리 일대의 정량적 해수면 변동)

  • Kim, Jeong-Yun;Yoon, Soon-Ock;Yang, Dong Yoon;Hwang, Sangill
    • Journal of The Geomorphological Association of Korea
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    • v.24 no.3
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    • pp.13-25
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    • 2017
  • This study is quantitative reconstruction of palaeo sea level records around Sinduk-ri, Gochang-Gun. 7 cores were collected from GC14 to GC18 in order to examine the entire sedimentary facies and reconstruct the sea level records. The cores were analysed by AMS, sedimentary facies, diatom and WA-pls. As a result of the diatom analysis, diatom zone were classified as No diatom zone, B1 zone, M zone and B2 zone. The result of WA-pls was that the sea level was about 1.5m lower than the present level around 6,000 BP and about 1m lower during last 5,000 BP. Thereafter, sea level rose to the present during the Mc sub-diatom zone period. Moreover, during the Md sub-diatom zone period, sea level was about 0.5m higher than the present.

Mid- to Late Holocene Progradational Pattern of Shinduri Dunefield: Implications for Sea Level and Climatic Changes in the Western Coast of Korea (홀로세 중기 이후 신두리 해안사구의 성장 : 기후변화 및 해수면 변동과의 관련 가능성)

  • HONG, Seongchan;CHOI, Jeong Heon;KIM, Jong Wook
    • 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.

The Relationship between Climate Change and Magnetic Susceptibility of Estuarine Sediments (하구역 퇴적물의 대자율 변화와 기후변화의 연관성)

  • Shin, Young-Ho
    • Journal of the Korean association of regional geographers
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    • v.17 no.5
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    • pp.521-535
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    • 2011
  • This study intended to explain the relationship between climate change and magnetic susceptibility of estuarine sediment. Data of OSL dating and magnetic susceptibility from estuarine tidal sediment were compared with various climate change data. During the last Holocene, the intense of magnetic susceptibility related with weaker Siberian High and stronger Asian Summer Monsoon. It is explained that high precipitation and runoff made much fluvial sediment input to the estuary. From the early to mid Holocene, there is no clear relationship between climate change and MS because of the much coastal sediment input caused by rapid sea level rise and the formation of upland soil and coastal marsh. These results contribute to reconstruct paleo-environmental changes of west coast of Korea, in the way of using benefit of ubiquitous estuarine tidal flats and relatively useful magnetic susceptibility methodoloy.

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