• Title/Summary/Keyword: 친링 충돌대

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Review on the Triassic Post-collisional Magmatism in the Qinling Collision Belt (친링 충돌대의 트라이아스기 충돌 후 화성작용에 대한 리뷰)

  • Oh, Chang Whan;Lee, Byung Choon;Yi, Sang-Bong;Zhang, Cheng Li
    • The Journal of the Petrological Society of Korea
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    • v.23 no.4
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    • pp.293-309
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    • 2014
  • The Qinling-Dabie-Sulu-Hongseong-Odesan collision belt was formed by the collision between the North China and South China Cratons during late Permian to Triassic. During the collision, Triassic post-collision igneous rocks regionally intruded in the Qinling and the Hongseong-Odesan collision belts which represent the western and eastern ends of the collision belt, respectively. However, no and minor Triassic post-collision igneous activities occur in the Dabie and Sulu belts respectively. The peak metamorphic pressure conditions along the Qinling-Dabie-Sulu-Hongseong-Odesan belt indicate that the slab break-off occurred at the depth of ultra-high pressure (UHP) metamorphic condition in the Dabie and Sulu belts and at the depths of high pressure (HP) or high pressure granulite (HPG) metamorphic condition in the Qinling and Hongseong-Odesan belts. In the Dabie and Sulu belts the heat supply from the asthenospheric mantle through the gab formed by slab break-off could not cause an extensive melting in the lower continental crust and lithospheric mantle directly below it due to the very deep depth of slab break-off. On the other hand, in the Qinling and Hongseong-Odesan belts, shallower slab break-off caused the emplacement of regional post collision igneous rocks. The post-collision igneous rocks occur in the area to the north of the Mianlu Suture zone in the western Qinling belt and crop out continuously eastwards into the areas to the north of the Shangdan Suture zone in the eastern Qinling belt through the areas within the South Qinling block. This distribution pattern of post collision igneous rocks suggests that the Triassic collision belt in the Mianleu Suture zone may be extended into the Shangdan Suture zone after passing through the South Qinling block instead into the boundary between the South Qinling block and the South China Craton.

충남지역 경기육괴에 분포하는 서산층군에 대한 자기특성 연구

  • 김완수;석동우;도성재
    • Proceedings of the KSEEG Conference
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    • 2003.04a
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    • pp.254-257
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    • 2003
  • 한반도에 대한 고지자기 연구는 유라시아 대륙의 지구조운동이 진행되었던 중생대 및 고생대암석에 대해 여러 사람들에 의해 활발히 수행되어왔다. 특히 1980년대 후반부터는 북중국지괴와 남중국지괴 사이의 충돌대인 친링-다비-수루 (Qinling-Dabie-Sulu) 조산대가 서해를 지나 한반도로 연장될 가능성에 대한 관심이 높아지고 있다. 한반도의 중부를 가로지르는 옥천대는 경기육괴와 영남육괴의 경제부로서 변성시기가 초기 Triassic으로 보고되고 있으며, 경기육괴 북부 휴전선 인접지역의 동서방향의 주향을 갖는 습곡-단층대인 임진강대는 남북 경계에 대한 정확한 정의는 성립되어있지는 않지만 Triassic에 광역변성작용을 받았다는 보고가 있으나, 이들 임진강대와 옥천대의 성인에 대한 논란은 현재에 이르기까지 계속되고 있다. (중략)

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The tectonic evolution of South Korea and Northeast Asia from Paleoproterozoic to Triassic (원생대 이후 트라이아스기까지의 남한과 동북아시아의 지구조 진화)

  • Oh, Chang-Whan
    • The Journal of the Petrological Society of Korea
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    • v.21 no.2
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    • pp.59-87
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    • 2012
  • Recent studies reveal that eclogite formed in the Hongseong area and post collision igneous rocks occurred throughout the Gyeonggi Massif during the Triassic Songrim Orogeny. These new findings derive the tectonic model in which the Triassic Qinling-Dabie-Sulu collision belt between the North and South China blocks extends into the Hongseong-Yangpyeong-Odesan collision belt in Korea. The belt may be further extended into the late Paleozoic subduction complex in the Yanji belt in North Korea through the Paleozoic subduction complex in the inner part of SW Japan. The collision belt divides the Gyeonggi Massif into two parts; the northern and southern parts can be correlated to the North and South China blocks, respectively. The collision had started from Korea at ca. 250 Ma and propagated to China. The collision completed during late Triassic. The metamorphic conditions systematically change along the collision belt:. ultrahigh temperature metamorphism occurred in the Odesan area at 245-230Ma, high-pressure metamorphism in the Hongseong area at 230 Ma and ultra high-pressure metamorphism in the Dabie and Sulu belts. This systematic change may be due to the increase in the depth of slab break-off towards west, which might be related to the increase of the amounts of subducted ocecnic slab towards west. The wide distribution of Permo-Triassic arc-related granitoids in the Yeongnam Massif and in the southern part of the South China block indicate the Permo-Triassic subduction along the southern boundary of the South China block which may be caused by the Permo-Triassic collision between the North and South China blocks. These studies suggest that the Songrim orogeny constructed the Korean Peninsula by continent collision and caused the subduction along the southern margin of the Yeongnam Massif. Both the northern and southern Gyeonggi Massifs had undergone 1870-1840 Ma igneous and metamorphic activities due to continent collision and subduction related to the amalgamation of Colombia Supercontinent. The Okcheon metamorphic belt can be correlated to the Nanhua rift formed at 760 Ma within the South China blocks. In that case, the southern Gyeonggi Massif and Yeongnam Massif can be correlated to the Yangtz and Cathaysia blocks in the South China block, respectively. Recently possible Devonian or late Paleozoic sediments are recognized within the Gyeonggi Massif by finding of Silurian and Devonian detrital zircons. Together with the Devonian metamorphism in the Hongseong and Kwangcheon areas, the possible middle Paleozoic sediments indicate an active tectonic activity within the Gyeonggi Massif during middle Paleozoic before the Permo-Triassic collision.

Structural Geometry, Kinematics and Microstructures of the Imjingang Belt in the Munsan Area, Korea (임진강대 문산지역의 구조기하, 키네마틱스 및 미세구조 연구)

  • Lee, Hyunseo;Jang, Yirang;Kwon, Sanghoon
    • Economic and Environmental Geology
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    • v.54 no.2
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    • pp.271-283
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    • 2021
  • The Imjingang Belt in the middle-western Korean Peninsula has tectonically been correlated with the Permo-Triassic Qinling-Dabie-Sulu collisional belt between the North and South China cratons in terms of collisional tectonics. Within the belt, crustal-scale extensional ductile shear zones that were interpreted to be formed during collapsing stage with thrusts and folds were reported as evidence of collisional events by previous studies. In this study, we tried to understand the nature of deformation along the southern boundary of the belt in the Munsan area based on the interpretations of recently conducted structural analyses. To figure out the realistic geometry of the study area, the down-plunge projection was carried out based on the geometric relationships between structural elements from the detailed field investigation. We also conducted kinematic interpretations based on the observed shear sense indicators from the outcrops and the oriented thin-sections made from the mylonite samples. The prominent structures of the Munsan area are the regional-scale ENE-WSW striking thrust and the N-S trending map-scale folds, both in its hanging wall and footwall areas. Shear sense indicators suggest both eastward and westward vergence, showing opposite directions on each limb of the map-scale folds in the Munsan area. In addition, observed deformed microstructures from the biotite gneiss and the metasyenite of the Munsan area suggest that their deformation conditions are corresponding to the typical mid-crustal plastic deformation of the quartzofeldspathic metamorphic rocks. These microstructural results combined with the macro-scale structural interpretations suggest that the shear zones preserved in the Munsan area is mostly related to the development of the N-S trending map-scale folds that might be formed by flexural folding rather than the previously reported E-W trending crustal-scale extensional ductile shear zone by Permo-Triassic collision. These detailed examinations of the structures preserved in the Imjingang Belt can further contribute to solving the tectonic enigma of the Korean collisional orogen.

Geochronological and Geochemical Studies for Triassic Plutons from the Wolhyeonri Complex in the Hongseong Area, Korea (홍성지역 월현리 복합체 내에 분포하는 트라이아스기 심성암류의 지질연대학 및 지구화학적 연구)

  • Oh, Jae-Ho;Kim, Sung Won
    • Economic and Environmental Geology
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    • v.46 no.5
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    • pp.391-409
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    • 2013
  • The Hongseong area of the southwestern Gyeonggi massif is considered to be part of suture zone that is tectonically correlated with the Qinling-Dabie-Sulu belt of China in terms of the preservation of collisional evidences during Triassic in age. The Wolhyeonri complex, preserved at the center of the Hongseong area, consists mainly of Neoproterozoic orthogneisses and Middle Paleozoic intermediate- to high-grade metamorphic schists, orthogneisses and mafic metavolcanics. The area includes various Middle to Late Triassic intrusives (e.g. dyke or stock). They are mainly monzonite and aplite with small intrusions of monzodiorit, syenite and diorite in composition. The SHRIMP U-Pb zircon ages yield 237 Ma to 222 Ma. The geochemistry of the studied Triassic intrusives show similar subuction- or arc-type signatures having Ta-Nb troughs, depletion of P and Ti, and enrichment of LILEs (large ion lithophile elements). In addition, the Triassic plutons in the Hongseong area, including those from this study, mostly possess high-K calc-alkaline to shoshonitic tectonic affinity. These results could be tectonically correlated to the post-collisional magmatic event following the Triassic collision between the North and South China blocks in China. Therefore, the Triassic plutons in the Hongseong area offer an important insight into the Triassic geodynamic history of the NE Asian region.

이온현미분석기를 사용한 남서부 경기육괴 변성암류의 U-Pb 저어콘 연대: 남중국지괴와의 대비 가능성

  • 조문섭
    • Proceedings of the Mineralogical Society of Korea Conference
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    • 2001.06a
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    • pp.141-142
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    • 2001
  • 남서부 경기육괴의 편마암류로부터 분리된 저어콘(zircon) 입자를 대상으로, 이온현미분석기(ion microprobe)를 사용한 U-Pb 연대를 구하였다. 그 결과는 후기 원생대(약 820 Ma) 뿐만 아니라 오르도비스기에 상당한 화성활동이 한반도에 있었음을 지시한다. 우리 나라 후기 원생대의 화성-변성 활동에 대해 알려져 있는 바는 극히 제한적이어서 후속연구가 필수적이며, 이러한 연구는 한반도의 지체구조적 변천사를 로디니아 초대륙(Rodinia supercontinent)의 생성-분리와 관련해 재조명할 수 있는 기회를 제공할 것이다. 또한 오르도비스기의 화성작용은 그동안 논란이 되어 왔던 소위 “칼레도니아(Caledonian)” 변동 (cf. 조문섭, 2000)에 대한 또 다른 증거를 제공해준다. 저어콘의 연대측정은 서호주의 커튼공업대학교에 설치되어 있는 SHRIMP-II(Sensitive High-Resolution Ion Microprobe-II; 고감도-고분해능 이온현미분석기)를 사용하였으며, 시료 준비 및 분석방법은 기존에 보고된 바와 같다 (e.g., Kinny et al., 1999). 분석된 3개의 암석 시료(1006-5, 8, 9)는 경기육괴의 남서부에 위치한 홍성 지역의 정편마암들이다. 1006-8 시료는 Turek and Kim (1996)이 전통적인 방법을 사용해 687$\pm$5 Ma의 U-Pb 저어콘 연대를 보고한 바 있는 화강암질 편마암 (시료번호, KJ43)에 해당된다. 두 개의 다른 시료는 1006-8 주변에서 산출하는 전형적인 경기육괴의 편마암류로서 화강암질 정편마암이다. 이들 시료로부터 분리된 저어콘 입자들은 대부분 화성기원의 누대구조와 자형의 결정형태를 보여준다. 과성장띠(overgrouth rims)는 1006-5 시료에서 흔하게, 그리고 1006-9 시료에서 매우 드물게 관찰된다. 음극선발광(cathodoluminescence) 영상의 해석을 통해 저어콘 결정의 성장사를 유추하였으며, 이를 바탕으로 이온현미분석 점(spot)을 정하였다. U-Pb-Th 자료는 퍼스(Perth) 저어콘 스탠다드 (CZ3, 564 Ma, $^{206}$Pb/$^{238}$U=0.0914)를 사용하였다. 아래에 기술하는 연대는 모두 $^{206}$Pb/$^{238}$U 연대에 해당된다. 두 개의 화강암질 편마암 시료로부터 구한 U-Pb 저어콘 연대는 각각 812 $\pm$ 14 Ma(1006-8)와 822 $\pm$ 17 Ma(1006-9)로 분석오차 내에서 서로 일치한다. 이 결과는 춘천 및 전곡 지역의 석류석 각섬암에서 보고된 Sm-Nd 전암연대(852 $\pm$ 24 Ma 및 824 $\pm$ 143 Ma; Lee and Cho, 1995; Ree et al., 1996)와 잘 부합한다. 따라서 후기 원생대 기간 중 화성활동이 한반도에서 광범위하게 일어났음을 시사한다. 한편, 1006-9 시료에서는 예외적으로 한 개의 저어콘 입자 주변부(rim)에서 매우 얇은 과성장띠가 관찰되었으며, 두 개의 점 분석으로부터 구한 U-Pb 저어콘 연대는 약 235 Ma이다. 이 띠는 또한 변성기원의 저어콘에서 흔히 관찰되는 작은 W (<0.05) 비를 보인다. 1006-5 시료는 위 두 시료로부터 수 km 떨어진 지점에서 채집하였으나, 저어콘 연대는 상이한 기록을 보여준다. 즉 매우 작은 Th/U (<0.01) 값을 갖는 저어콘의 주변부에서 223 $\pm$ 5 Ma의 연대가 잘 정의되며, 이는 1006-9 시료에서 관찰된 결과와 함께 트라이아스기의 고온변성작용이 백립암상에 가까운, 매우 높은 온도에 달하였음을 지시한다. 한편 저어콘의 중심부는 335-473 Ma의 비교적 넓은 연대 분포를 보인다. 이는 저어콘이 실제 성장한 연대를 지시하기보다는 트라이아스기의 변성작용에 따른 납손실(Pb loss) 그리고 누대 규모보다 더 큰 빔 크기(beam size, 약 30 $\mu\textrm{m}$)의 영향일 것으로 해석된다. 또한 저어콘이 다양한 외래물질로부터 기원했다는 증거가 관찰되지 않으므로, 이 정편마암의 모암은 오르도비스기(약 430-470 Ma)에 관입하였을 것으로 생각된다. 따라서 그동안 논란이 되어 왔던 소위 “칼레도니아” 변동이 한반도 내에 실존하였을 가능성을 시사한다. 이상의 결과를 종합하여 볼 때, 경기육괴의 변성암류는 후기 원생대 이후 다양한 저어콘의 성장사를 기록하고 있음을 알 수 있다: 즉 (1) 후기원생대(약 820 Ma)의 화성작용; (2) 오르도비스기(약 450 Ma)의 화성작용: 그리고 (3) 트라이아스기 (약 223 Ma)의 부분용융을 수반한 고온 변성작용으로 대표된다. 이러한 지질연대는, 옥천변성대에서 얻어진 756 Ma의 저어콘 연대(Lee et al., 1998)와 더불어, 친링-다비-수루(Qinling-Dabie-Sulu) 대륙 충돌대와 양쯔 지괴에서 보고된 지질연대 결과와 잘 부합한다. 따라서 지구연대학적으로 경기육괴가 북중국보다는 대륙충돌대를 포함하는 남중국지괴에 속할 것으로 결론지을 수 있다.

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Geochronological and Geotectonic Implications of the Serpentinite Bodies in the Hongseong Area, Central-western Korean Peninsula (한반도 중서부 홍성지역 내에 분포하는 사문암체의 지질연대학 및 지구조적 의미)

  • Kim, Sung Won;Park, Seung-Ik
    • Economic and Environmental Geology
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    • v.49 no.4
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    • pp.249-267
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    • 2016
  • The Hongseong area of the central-western Korean Peninsula is considered to be a part of collision zone that is tectonically correlated to the Qinling-Dabie-Sulu belt of China. The area includes the elliptical-shaped serpentinized ultramafic bodies, together with mafic rocks. The studied bodies are in contact with the surrounded Neoproterozoic alkali granites at the Baekdong and Wonnojeon bodies and the Paleoproterozoic Yugu gneiss at the Bibong body. The Baekdong body contains the blocks of the Neoproterozoic alkali granites and the Late Paleozoic metabasites. The Bibong body also includes the Neoproterozoic alkali granite blocks. The Mesozoic intrusive rocks are also recognized at the Baekdong, Wonnojeon and Bibong bodies. On the other hand, the Early Cretaceous volcanic rocks are occurred at the Bibong body. The detrital zircon SHRIMP U-Pb ages of the serpentinites at three bodies range variously from Neoarchean to Middle Paleozoic at the Baekdong body, and from Neoarchean to Early Cretaceous at the Wonnojeon and Bibong bodies. Although serpentinization does not generally produce minerals suitable for direct isotopic dating, the youngest Middle Paleozoic age at the Baekdong body and the Early Cretaceous age at the Wonnojeon and Bibong bodies indicate the possible upper age limit for the (re)serpentinization. Especially, the Early Cretaceous serpentinization ages may be related to the widespread Early Cretaceous igneous activity in the central-southern Korean Peninsula. Age results for the serpentinite bodies and the included blocks of the studied serpentinized ultramafic bodies in the Hongseong area, therefore, provide several possible interpretations for the serpentinization ages of the ultramafic rocks as well as the geotectonic implications of serpentinization, requiring more detailed study including other serpentinized ultramafic bodies in the Hongseong area.

Stratigraphic response to tectonic evolution of sedimentary basins in the Yellow Sea and adjacent areas (황해 및 인접 지역 퇴적분지들의 구조적 진화에 따른 층서)

  • Ryo In Chang;Kim Boo Yang;Kwak won Jun;Kim Gi Hyoun;Park Se Jin
    • The Korean Journal of Petroleum Geology
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    • v.8 no.1_2 s.9
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    • pp.1-43
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    • 2000
  • A comparison study for understanding a stratigraphic response to tectonic evolution of sedimentary basins in the Yellow Sea and adjacent areas was carried out by using an integrated stratigraphic technology. As an interim result, we propose a stratigraphic framework that allows temporal and spatial correlation of the sedimentary successions in the basins. This stratigraphic framework will use as a new stratigraphic paradigm for hydrocarbon exploration in the Yellow Sea and adjacent areas. Integrated stratigraphic analysis in conjunction with sequence-keyed biostratigraphy allows us to define nine stratigraphic units in the basins: Cambro-Ordovician, Carboniferous-Triassic, early to middle Jurassic, late Jurassic-early Cretaceous, late Cretaceous, Paleocene-Eocene, Oligocene, early Miocene, and middle Miocene-Pliocene. They are tectono-stratigraphic units that provide time-sliced information on basin-forming tectonics, sedimentation, and basin-modifying tectonics of sedimentary basins in the Yellow Sea and adjacent area. In the Paleozoic, the South Yellow Sea basin was initiated as a marginal sag basin in the northern margin of the South China Block. Siliciclastic and carbonate sediments were deposited in the basin, showing cyclic fashions due to relative sea-level fluctuations. During the Devonian, however, the basin was once uplifted and deformed due to the Caledonian Orogeny, which resulted in an unconformity between the Cambro-Ordovician and the Carboniferous-Triassic units. The second orogenic event, Indosinian Orogeny, occurred in the late Permian-late Triassic, when the North China block began to collide with the South China block. Collision of the North and South China blocks produced the Qinling-Dabie-Sulu-Imjin foldbelts and led to the uplift and deformation of the Paleozoic strata. Subsequent rapid subsidence of the foreland parallel to the foldbelts formed the Bohai and the West Korean Bay basins where infilled with the early to middle Jurassic molasse sediments. Also Piggyback basins locally developed along the thrust. The later intensive Yanshanian (first) Orogeny modified these foreland and Piggyback basins in the late Jurassic. The South Yellow Sea basin, however, was likely to be a continental interior sag basin during the early to middle Jurassic. The early to middle Jurassic unit in the South Yellow Sea basin is characterized by fluvial to lacustrine sandstone and shale with a thick basal quartz conglomerate that contains well-sorted and well-rounded gravels. Meanwhile, the Tan-Lu fault system underwent a sinistrai strike-slip wrench movement in the late Triassic and continued into the Jurassic and Cretaceous until the early Tertiary. In the late Jurassic, development of second- or third-order wrench faults along the Tan-Lu fault system probably initiated a series of small-scale strike-slip extensional basins. Continued sinistral movement of the Tan-Lu fault until the late Eocene caused a megashear in the South Yellow Sea basin, forming a large-scale pull-apart basin. However, the Bohai basin was uplifted and severely modified during this period. h pronounced Yanshanian Orogeny (second and third) was marked by the unconformity between the early Cretaceous and late Eocene in the Bohai basin. In the late Eocene, the Indian Plate began to collide with the Eurasian Plate, forming a megasuture zone. This orogenic event, namely the Himalayan Orogeny, was probably responsible for the change of motion of the Tan-Lu fault system from left-lateral to right-lateral. The right-lateral strike-slip movement of the Tan-Lu fault caused the tectonic inversion of the South Yellow Sea basin and the pull-apart opening of the Bohai basin. Thus, the Oligocene was the main period of sedimentation in the Bohai basin as well as severe tectonic modification of the South Yellow Sea basin. After the Oligocene, the Yellow Sea and Bohai basins have maintained thermal subsidence up to the present with short periods of marine transgressions extending into the land part of the present basins.

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