• Title, Summary, Keyword: paleo-shoreline

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The Formative Processes and Ages of Paleo-coastal Sediments in Daepo-dong Sacheon-si in the Southern Coast, South Korea: Evaluation of the Mode and Rate of the Late Quaternary Tectonism (II) (남해안 사천시 대포동 일대에 분포하는 고해안 퇴적물의 형성 과정과 형성 시기: 한반도 제4기 후기 지각운동의 양식과 변형률 산출을 위한 연구(II))

  • Shin, Jaeryul;Hong, Seongchan
    • Journal of The Geomorphological Association of Korea
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    • v.25 no.3
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    • pp.57-70
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    • 2018
  • This study restores onshore paleo-shoreline records and establishes the nature and strain rate of neotectonism by investigating the existence and formative age of paleo-coastal sediments emerged around Sacheon-si in the Southern part of the Korean peninsula. As a result, paleo-sand bars representing 5m of the paleo-shoreline from high tide level are formed in Sacheon-si, and the formation age of these is confirmed as MIS 5c at approximately 100,000 year BP through rock surface luminescence dating to rounded gravels in paleo-sand bars. Although it is difficult to establish the uplift rate of crust precisely due to incomplete restoration of sea level records during the last interglacial stage, the uplift rate along the Southern coast of the peninsula was assumed approximately 0.72 lower than the Eastern coast during the late Quaternary in comparison to the 1st marine terrace along the Eastern coast.

The paleo-shoreline and formation age of the 1st marine terrace in Heunghae-eup Pohang City, South Korea : evaluation of the mode and rate of the late Quaternary tectonism (I) (포항시 흥해읍 일대 해안단구 제1면의 구정선 고도와 형성 시기 - 한반도 제4기 후기 지각운동의 양식과 변형률 산출을 위한 연구(I) -)

  • Shin, Jae Ryul;Park, Kyung Geun
    • Journal of the Korean association of regional geographers
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    • v.22 no.3
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    • pp.703-713
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    • 2016
  • This study documents the altitude of paleo-shoreline and formation age of the $1^{st}$ marine terrace emerged around Heunghae-eup Pohang City (South Korea). As a result, the $1^{st}$ terrace representing 10 m of the paleo-shoreline was formed at MIS 5c around 100,000 BP and was influenced repetitive sedimentation of sea-wave till regression of MIS 5a. The result is recognized as a definite truth for the $1^{st}$ terrace in the eastern coast of the Korean peninsula based on synthetic reviews of previous studies and cross-validation of absolute age data. Furthermore, this study deduces a sea stand at MIS 5c from the geomorphological contrast method, but precise determination of paleo-shoreline of the $2^{nd}$ terrace should be required to estimate that of MIS 5c.

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Marine terrace and its implications to paleoenvironment during the Quaternary at Suje-ri - Suryum-ri of the East coast of Gyeongju, SE Korea (한반도 남동부 경주시 수제리-수렴리의 해안단구와 제4기 환경변화)

  • HWANG, Sangill;SHIN, Jaeryul;YOON, Soon-Ock
    • Journal of The Geomorphological Association of Korea
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    • v.19 no.3
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    • pp.97-108
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    • 2012
  • During the last few decades, the ever-increasing knowledge of coastal morphogenic processes has made marine terraces the most recognizable, widespread and scientifically reliable records to determine both qualitatively and quantitatively the vertical movements that have affected the tectonically active coastal regions during the Quaternary. This study first aims to address the marine terrace records from Suje-ri to Suryum-ri along the coast of Gyeongju, SE Korea. Eight distinct flights of terraces, including HH YC, elevated up to 160 m above present sea level have been mapped along the coast of the study areas, and are designated $L_{II}$ to HH YC from the youngest to oldest. Based on the elevation of paleo-shoreline and inferred formation age for HH YC uplift rate since the middle Pleistocene has been estimated at 0.23 mm/year. Establishing the nature and timing of the uplift history derived from marine terraces provide a better understanding of neotectonic framework for explain enigmatic, complex landscape evolution in the Korean peninsula.

The Distribution, Ages and Uplift Ratio ofmarine Terraces in SE coast of Korea: Review (동해안 해성단구 분포, 형성시기 및 융기율 검토)

  • Kim, Ju-Yong;Yang, Dong-Yoon;Kim, Jin-Kwan;Lee, Jin-Young;Kim, Jeong-Chan;Hong, Sei-Sun;Oh, Keun-Chang;Choi, Don-Won
    • The Korean Journal of Quaternary Research
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    • v.19 no.1
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    • pp.27-40
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    • 2005
  • Researches onmarine terrace in Korea have been drastically progressed during the last two decades.main themes of researches include vertical and horizontal distribution of paleo-shoreline, sedimentary facies ofmarine terrace deposits, OSL dating of terrace deposits and estimation of uplift rate. At present, it is noted thatmarine terraces distributed at the same altitude do not always show the same sedimentary facies, nor have the same ages.marine terraces are generally divided into five terrace systems, of which ages increase in ascending order. There are some arguments about discrimination between 2nd and 3rd terrace systems and their age. The core discrepancy lies on the question of whether the level of the last interglacial terrace is on the level of about 20m or on the 30~35m(~40m) in altitude. The uplift rate based on the paleoshoreline distribution ranges between 0.10 and 0.20m/ka.

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Neogene Uplift in the Korean Peninsula Linked to Small-scaled Mantle Convection at Singking Slab Edge (소규모 맨틀 대류에 의한 한반도의 신제3기 이후 융기 운동)

  • Shin, Jae-Ryul;Sandiford, Mike
    • Journal of the Korean Geographical Society
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    • v.47 no.3
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    • pp.328-346
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    • 2012
  • This study provides quantitative constraints on Neogene uplift in the Korean peninsula using onshore paleo-shoreline records and seismic data. The eastern margin of Northeast Asia including Korea sits in the back-arc system behind the Western Pacific Subduction Zone, a complex trench triple junction of the Philippine Sea, Pacific, and Eurasian (Amurian) plates. An analysis of seismic data in the subduction zone shows that the pattern of uplift in the peninsula mirrors the extent of deep seismicity in subducting Pacific plate beneath. Combined with previous tomographic studies it is proposed that uplift is partly driven by asthenospheric upwelling caused by a sinking slab during the Neogene. In addition, the SHmax orientations of E-W and N-S trends in the peninsula are consistent with the prevailing in-situ stress fields in the eastern Eurasian continent generated by various plate boundary forces. The uplift in Korea during the Late Neogene is attributed, in part, to lithospheric failure relating to faulting movements, thus providing a link between dynamic effects of mantle upwelling at sinking slab edge and lithospheric responses driven by plate boundary forces.

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Application of 10Be Dating Technique for Marine Terrace Studies and Its Limitations (해안단구 연구를 위한 10Be 연대측정법의 적용과 한계점)

  • Shin, Jae-Ryul
    • Journal of the Korean earth science society
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    • v.36 no.6
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    • pp.512-519
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    • 2015
  • Although Quaternary marine terraces and onshore paleo-shoreline records provide clues to our understanding for the mode and nature of neotectonics in the Korean peninsula, it cannot be accomplished without knowledge on both independent information of the past sea level records and tectonic deformation field together with precise results of numerical dating for higher terraces. This study reported cosmogenic radionuclides ($^{10}Be$) dating results conducted in higher terraces in the eastern and western coasts of the Korean peninsula. As a result, the measured concentration ratio of $^9Be/^{10}Be$ and the exposure ages were much younger than expected. It implies that either there is possibility of error in experimental processes or the samples experienced a complex exposure history probably included a burial at some stage. Considering the past climatic conditions around the Korean peninsula and a possible complex exposure history after the emergence of marine terrace, the discovery of a suitable study area and a sampling site are an essential part of successful $^{10}Be$ dating technique.

Seismic Stratigraphy and Depositional History of Holocene Transgressive Deposits in the Southeastern Continental Shelf, Korea (한국 남동해역 홀로세 해침퇴적층의 탄성파층서 및 퇴적역사)

  • Yoo, Dong-Geun;Kim, Seong-Pil;Lee, Chi-Won;Park, Soo-Chul
    • Economic and Environmental Geology
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    • v.44 no.4
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    • pp.303-312
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    • 2011
  • Analysis of high-resolution seismic profiles from the southeastern continental shelf of Korea reveals that the Holocene transgressive deposits consist of five sedimentary units characterized by retrograding or backstepping depositional arrangements. Unit I, forming a linear sediment body along the shelf margin, is an ancient beach/shoreface deposit formed during the early stage of transgression. During the transgression, the paleo-channels were backfilled with fluvial or coastal-plain sediments, forming Unit II as an incised-channel fill deposit. The near-surface sediment was reworked and eroded by shoreface erosion, forming a thin lag of sands (Unit III) on the midshelf. During the middle stage of the transgression, the shoreline may have stabilized at around 70 - 80 m below the present sea level for some period of time to allow the formation of sand ridge systems (Unit IV). Unit V in the inner shelf was deposited in an estuarine environment during the middle to late stage of transgression. Such transgressive stratigraphic architecture is controlled by a function of lateral changes in the balance among rates of relative sea-level rise, sediment input and marine processes at any given time.