• The Korean Journal of Quaternary Research
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• v.3 no.1
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• pp.69-85
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• 1989

The depositional environments of the Pyung-Ahn Group sedimentary rocks, Jeongseon-Kun, Kangweondo, Korea are investigated. The environments are understood to be characteristic transitional from a typical shallow marine to a typical continental environment. Such transitional conditions are also understood in various parts of Quaternary and modern environment on the earth. In particular, the absence of detrital feldspar sand grains in the Manhang and Keumcheon Formation Sandstone body is described firstly in Korea, and the fact and possible mechanism are discussed.

• Economic and Environmental Geology
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• v.52 no.5
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• pp.367-379
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• 2019

Pyeongan Supergroup (PS) in the Taebaeksan basin preserves key geological evidences to understand the tectonometamorphic evolution of the Songrim orogeny that affected the formation of the Korean Peninsula during the late Paleozoic to early Mesozoic. The aims of this paper therefore are to investigate the characteristics of the Songrim orogeny based on the previous results of metamorphism and deformations of the PS, and then to review geological significance and research necessity of the PS. Age distributions and Th/U ratio of detrital zircon in the PS indicate that sedimentary environment of the Taebaeksan basin during the late Paleozoic was arc-related foreland basin and retro-arc foreland basin at the active continental margin. In addition, the main magmatic activities occurred in the early Pennsylvanian and Middle Permian, thus sedimentation and magmatic activities occurred simultaneously. The PS was affected by lower temperature-medium pressure (M1) and medium temperature and pressure (M2) regional metamorphism during the Songrim orogeny. During M1, slate and phyllite containing chloritoid, andalusite, kyanite porphyroblasts intensively deformed by E-W bulk crustal shortening combined with folding and shearing. And garnet and staurolite porphyroblasts were formed during the N-S bulk crustal shortening accompained by M2. Such regional metamorphism of the PS is interpreted to occur in an area where high strain zone is localized during ca. 220-270 Ma. In order to elucidate the evolution of the Taebaeksan basin and tectonic features of the Songrim orogeny, it is expected that the study will be carried out such as the regional distribution of metamorphic zones developed in the PS, characteristics and timing of deformations, and late Paleozoic paleo-geography of the Taebaeksan basin.

• The Journal of Engineering Research
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• v.2 no.1
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• pp.175-182
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• 1997

Field relationships indicate that the Jumchon granite intruded the Pyungan Supergroup but the Daedong Supergroup overlies Jumchon granite nonconformably. This relationship suggests that the Jumchon granite intruded after the sedimentation of the Pyungan Supergroup (at Late Permian or younger), but before the sedimentation of the Daedong Supergroup (at Early Triassic). The Jumchon granite intruded thrusts within Pyungan Supergroup indicating that the thrust event occurred after the sedimentation of the Pyungan Supergroup but before the intrusion of Jumchon granite. This justifies a narrow age bracket of the first thrusting event of the Mungyeong area, from Late Permian to Early Triassic. In other localities, rocks of the Daedong Supergroup override the rocks of Pyungan Supergroup by thrusts, indicating that another thrust event occurred after sedimentation of the Daedong Supergroup (after Early Devonian).

• The Journal of the Petrological Society of Korea
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• v.26 no.1
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• pp.73-82
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• 2017

We determined SHRIMP U-Pb ages of the detrital zircons separated from the Bangnim Group of the Pyeongchang area to constrain its depositional age. As the result, the minimum age group yielded $^{206}Pb/^{238}U$ age of $450.3{\pm}4.2Ma$ (n=3), suggesting depositional age younger than Late Ordovician. Therefore, the Bangnim Group cannot be a Precambrian sedimentary formation but is younger than Myobong Formation of the Early Paleozoic Joseon Supergroup of the Taebaeksan basin. Such a depositional age implies that the Bangnim Group and structurally overlying Jangsan Quartzite should be in fault contact, suggesting that the Jangsan Quartzite, Myobong Formation and Pungchon Limestone thrusted over the Bangnim Group. The zircon U-Pb age distribution pattern of the Bangnim Group resembles those of the Early Paleozoic Myobong and Sambangsan Formations of the Taebaeksan basin and seemingly Middle Paleozoic Daehyangsan Quartzite and the Taean Formation. However, detrital zircon U-Pb age patterns of the Late Paleozoic Pyeongan Supergroup are quite distinct from them, suggesting drastic change in provenance of the detrital zircon supply. Therefore, we suggest that the Bangnim Group was deposited before the Pyeongan Supergroup.

• Economic and Environmental Geology
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• v.48 no.4
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• pp.287-299
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• 2015

The metapsammite distributed in the Yeongam-Gangjin area had been classified into age-unknown Yongamsan Formation, Seologri Formation and age-unknown Seogisan Formation, and these formations are reported as each other different formations. These formations have been renamed Precambrian Galdu or Permian Songjong Formations. In this study, we present detrital zircon SHRIMP U-Pb age data from the metapsammite to examine deposition time and stratigraphy. The analyzed U-Pb zircon ages dominantly reveal Paleoproterozoic ages of ca. 1.87Ga and the youngest detrital grains are constrained by the age of 246-265 Ma. The youngest age indicates late Permian or early Triassic for the deposition time. Therefore, the metapsammite in the Yeongam-Gangjin area is considered to be the upper formation of the late Paleozoic Pyeongan Group which is correlated with the Gohan-Donggo Formations or Nokam Formation of the Samcheock coal field and the Cheonunsan Formation of the Hwasun coal field. The metapsammite of the study area is the late Paleozoic Pyeongan Group by the zircon age rather than Precambrian Galdu and Permian Songjeong Formations are no longer meaningful. Therefore, we propose the upper Paleozoic 'metapelite' and 'metaspammite', or original formation name defined by 1:50,000 geological maps, instead of Galdu and Songjeong Formations.

• Proceedings of the Speleological Society Conference
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• 1993.07a
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• pp.76-88
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• 1993

1962년 대한지질학회에서 조사 발표한 태백산지구지질단 제4쪽과 제8쪽에 의하면 동해시 부근의 지질은 ［그림 1］과 같다. 이 지질도 남반부에 천곡동 동굴지대가 포함되어 있는데 동해시 일대의 지질은 조선계층군의 중부와 평안계층군의 대부분, 이들에 관입한 편마상화강암과 우질화강암을 주로하고 이들을 부정합으로 덮은 홍적층(단구층), 중적층으로 이루어져 있다.(중략)

• Journal of the Speleological Society of Korea
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• v.27 no.28
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• pp.53-67
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• 1991

1962년 대한지질학회에서 조사 발표한 태백산지구지질권 제4쪽과 제8쪽에 의하면 동해시 부근의 지질은 ［그림 1］과 같다. 이 지질도 남반부에 천곡동 동굴지대가 포함되어 있는데 동해시 일대의 지질은 조선계층군의 중부와 평안계층군의 대부분, 이들에 관입한 편마상화동굴과 우질화강암을 주로 하고 이들을 부정합으로 덮은 홍적층, 중적층으로 이루어져 있다.(중략)

• Proceedings of the KSEEG Conference
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• 2005.04a
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• pp.320-323
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• 2005

• The Journal of the Petrological Society of Korea
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• v.23 no.4
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• pp.311-324
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• 2014

The Hongjeom formation of the Pyeongan Supergroup in the Munkyeong coalfield mainly consists of metapsammite and metapelites. Metampelites occur as slate preserving chloritoid+chlorite+muscovite and andalusite+biotite+chlorite+muscovite mineral assemblages. Chloritoid and andalusite occur as porphyroblast, and the matrix composed of fine-grained micas. Metamorphic P-T conditions for these mineral assemblages are $510-520^{\circ}C$ and 3.0-3.5kbar based on P-T pseudosection in $MnO-K_2O-FeO-MgO-Al_2O_3-SiO_2-H_2O(MnKFMASH)$ system and isopleth intersections of Fe/(Fe+Mg) ratios in chloritoid and chlorite. The medium temperature and low pressure metamorphism resulted from a higher geothermal gradient ($40-45^{\circ}C/km$) condition than that of burial metamorphism. The youngest (SHRIMP U-Pb age; ca. 327-310 Ma) detrital zircon grains from the Hongjeom formation display oscillatory zoning and relatively high Th/U ratio (0.60-1.12). Based on the previous sedimentary, paleontological, and geochronological studies in the Taebaeksan basin together with results of this study, we suggest that (1) initial deposition of the Hongjeom formation was contemporaneous with a magmatic activity in the provenance, (2) the Pyeongan Supergroup was deposited in an arc-related basin at an active continental margin during the Carboniferous to Permain, and (3) magmatic activities occurred repetitively in relatively short interval in the active continental margin had continuously supplied sediments to the basin.

• Journal of the Speleological Society of Korea
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• v.4 no.5
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• pp.27-35
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• 1979

우리나라에는 캠브로-오오도비스기에 속하는 조선누층군의 석회암이 넓게 분포되어 있는데 그들은 3개의 분포지역으로 구분된다. 즉 평안지향사, 삼척지향사 및 옥천지향사와 기타 소규모의 분포를 이루는 지역들이다. 이들 지역에는 국지적으로 Karst지형의 특징이 잘 관찰된다. 우리나라의 Karst 지형에 대한 연구는 개략적인 조사와 연구에 의하여 발표된바 있다.(중략)