• Title/Summary/Keyword: 백악기 퇴적층

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Occurrence of Placer Gold Deposits from the Takaoi Area of the Middle Kalimantan, Indonesia (인도네시아 중부 칼리만탄 따까오이 지역 사금광상의 산출상태)

  • Kim In-Joon;Lee Jae-Ho
    • Economic and Environmental Geology
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    • v.39 no.2 s.177
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    • pp.191-212
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    • 2006
  • Placer gold deposits is mainly distributed in the Takaoi area. The alluvium is unconsolidated or semiconsolidated deposit consisting of gravel, sand, and soil beds in ascending order. They unconformably overlies the Carboniferous-Permian schist and Cretaceous granodiorite substratum. Based on detailed facies analysis, the alluvium can be interpreted as a typical fluvial deposits containing gravel and sand beds of channel-fill unit and soil deposit of floodplain. Gold grains are included mainly in the gravel bed and vein quartz is only contained gold among all kinds of gravels. These features indicates that the source rock of the gold grain is vein quartz and gold grains are separated from vein quartz during transport and abrasion. The reserves of gold in this area reach to at least 792 kg.

Sandstone composition and Paleoclimate of cretaceous Jinju and Iljig Formations of the Western Euiseong Area in the northern Part of Kyongsang Basin (경상분지북부 의성서부지역 백악기 진주층.일직층의 사암성분 및 고기후)

  • 박진아;이용태;김상욱;고인석
    • The Journal of the Petrological Society of Korea
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    • v.6 no.2
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    • pp.111-122
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    • 1997
  • Provenance type and paleoclimate of the Jinju and Iljig formation were studied on the basis of compositions of sandstones from the western Euiseong area in the northern part of Kyong-sang basin. The average compositions of quartz, feldspar and lithic grain(Q:F:L) from the sandstones are 53:40:7 and 50:46:4 for Jinju and Iljig formations, respectively. The values fall into the arkosic arenite field. Petrographic detrital modes of the sandstones mainly suggest transitional continental block for the tectonic setting of the provenance. All sandstones from the Jinju and IIjig formations show chemical compositions close to average values of arkose(Pettijohn, 1975). $Na_2O$ contents is relatively high. $Fe_2O_3$(total iron) and MgO contents decrease with increasing $SiO_2$ contents since the framework grains of arkoses supposed to be derived from granitic rocks are poor in ferromagnesian minerals. The detrital framework grains still possess climatic signs even though the grains were more or less altered during deep burial. Bivariant plot of Suttner and Dutta(1986) suggests semi-arid to semi-humid paleoclimate during the deposition of the Jinju and Iljig sandstones.

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Development and Application of Teaching Materials for Geological Fieldwork in the Area of Bongwhabong, Buan-gun, Jeonbuk, Korea (전북 부안군 봉화봉 일대의 야외지질 학습자료 개발 및 적용)

  • Park, Jae-Moon;Ryang, Woo-Hun;Cho, Kyu-Seong;Kim, Seung-Bum
    • Journal of the Korean earth science society
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    • v.30 no.7
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    • pp.883-896
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    • 2009
  • This study is to develop teaching materials for geological fieldwork around Bonghwabong area in the national park of the Byeonsan Peninsula, Buangun, Jeonbuk. The developed materials are applied in the geological fieldwork of science high school students to maximize the effects of use. The sedimentary succession of the Bonghwabong area in the Cretaceous age, Mesozoic, represents large-scale and distinctive sedimentary structures on the sea cliffs, which are utilized as teaching materials for earth science fieldwork. The area of Bonghwabong also comprises various geological structures related to advanced learning programs as well as those within the curriculum of high school earth science. A five-step fieldwork model was applied to 15 students in clubs related to earth science in a science high school. This study used a qualitative methodology to analyze students' responses that were gathered about the process of fieldwork. During the activity, a qualitative analysis was carried out by using discussions and interviews both with the students and the teacher. Results indicated that the fieldwork activity using teaching materials was effective in helping the students improve their self-directed learning and practical understanding of earth science.

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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Granites and Tectonics of South Korea (남한(南韓)의 화강암류(花崗岩類)와 지각변동(地殼變動))

  • Kim, Ok Joon
    • Economic and Environmental Geology
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    • v.8 no.4
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    • pp.223-230
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    • 1975
  • South Korea is divided tectonically into four segments. The Kyonggi-Ryongnam massif is composed of Precambrian schists and gneisses and consititutes a base for the succeeding formations. The Okcheon geosynclinal zone in the Kyonggi-Ryongnam massif strectches from southwest to northeast diagonally across the peninsula in a direction known as the Sinian direction. Its northeastern part is composed primarily of Paleozoic to early Mesozoic sedimentary formations and the southwestern part of the late Precambrian Okcheon metamorphic series. The Kyongsang basin occupies the southeast and southwest of the peninsula and is made up of a thick series of Cretaceous terrestrial sedimentary and andesitic rocks. A few small Tertiary basins are scattered in the eastern coastal area and in Cheju Island, and are composed of marine sedimentary and basaltic rocks. Jurassic Daebo granites intrude the Kyonggi-Ryongnam massif and the Okcheon zone in the Sinian direction, whereas late Cretaceous Bulkuksa granites are scattered randomly in the Kyongsang basin.

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Basaltic Andesite-Siltstone Peperite in the Gyehwari Formation (Cretaceous) (백악기 계화리층 내 현무암질 안산암-실트암 페퍼라이트)

  • Noh, Beyong-Seob;Park, Jae-Moon;Kim, Seung-Bum;Ryang, Woo-Hun
    • Journal of the Korean earth science society
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    • v.30 no.1
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    • pp.33-39
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    • 2009
  • This paper presents the occurrence and characteristics of the basaltic andesite-siltstone peperite in the lower part of the Gyehwari Formation (Cretaceous), Buan-gun, Jeonbuk province, SW Korea. The peperite is associated with tabular basaltic andesite body, concordantly intercalated with red siltstone and silty sandstone interbeds of floodplain facies. Development of the peperite along the upper margin of the andesite and its textural transition from a dispersed blocky type inward into a closely packed type collectively indicate an intrusive origin (?sill) of the andesite. Magma intrusion and subsequent peperite formation suggest an active syndepositional volcanism since the early stage of evolution of the Gyehwa Basin. The andesite is dated at Late Cretaceous (Santonian) by K-Ar whole-rock radiometric method.

Seismic Facies Classification of Igneous Bodies in the Gunsan Basin, Yellow Sea, Korea (탄성파 반사상에 따른 서해 군산분지 화성암 분류)

  • Yun-Hui Je;Ha-Young Sim;Hoon-Young Song;Sung-Ho Choi;Gi-Bom Kim
    • Journal of the Korean earth science society
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    • v.45 no.2
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    • pp.136-146
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    • 2024
  • This paper introduces the seismic facies classification and mapping of igneous bodies found in the sedimentary sequences of the Yellow Sea shelf area of Korea. In the research area, six extrusive and three intrusive types of igneous bodies were found in the Late Cretaceous, Eocene, Early Miocene, and Quaternary sedimentary sequences of the northeastern, southwestern and southeastern sags of the Gunsan Basin. Extrusive igneous bodies include the following six facies: (1) monogenetic volcano (E.mono) showing cone-shape external geometry with height less than 200 m, which may have originated from a single monogenetic eruption; (2) complex volcano (E.comp) marked by clustered monogenetic cones with height less than 500 m; (3) stratovolcano (E.strato) referring to internally stratified lofty volcanic edifices with height greater than 1 km and diameter more than 15 km; (4) fissure volcanics (E.fissure) marked by high-amplitude and discontinuous reflectors in association with normal faults that cut the acoustic basement; (5) maar-diatreme (E.maar) referring to gentle-sloped low-profile volcanic edifices with less than 2 km-wide vent-shape zones inside; and (6) hydrothermal vents (E.vent) marked by upright pipe-shape or funnel-shape structures disturbing sedimentary sequence with diameter less than 2 km. Intrusive igneous bodies include the following three facies: (1) dike and sill (I.dike/sill) showing variable horizontal, step-wise, or saucer-shaped intrusive geometries; (2) stock (I.stock) marked by pillar- or horn-shaped bodies with a kilometer-wide intrusion diameter; and (3) batholith and laccoliths (I.batho/lac) which refer to gigantic intrusive bodies that broadly deformed the overlying sedimentary sequence.

백악기 영동층군에서 산출된 구과류 화석의 특징과 고기후적 의미

  • Seo Ji-Hye;Kim Jong-Heon
    • 한국지구과학회:학술대회논문집
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    • 2006.02a
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    • pp.239-244
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    • 2006
  • 충청북도 영동 지역에 분포하는 영동층군은 옥천변성대에 있는 소규모 퇴적분지중의 하나이다. 영동층군의 지질과 고생물에 관한 연구는 옥천변성대의 조구조운동과 관련한 퇴적분지 발달 규명과 아울러 경상분지와의 상호대비가 가능케 함으로써 이 시기의 한반도의 지질을 이해하는데 있어 매우 중요한 정보를 제공해 줄 수 있다(김규봉 등, 1986). 영동층군의 층서고생물학적 연구는 김규봉 등(1986), 전희영 등(1993), 최성자 등(1995)등의 연구가 있다. Shimamura (1927)는 영동층군에서 케이로레피드과(Cherolepidiaceae)에 속하는 식물화석의 산출을 처음 보고하였다. 이후 전희영 등(1993), 최성자 등(1995)이 영동층군에서 케이로레피드과에 속하는 식물화석을 다시 보고함으로써 영동층군에서 식물화석이 많이 산출될 가능성이 확인되었다. 본 연구에서는 식물화석의 연구에 중점을 두고 야외지질조사를 통하여 영동층군의 기존 화석산지와 새로운 화석산지로부터 많은 식물 화석을 채집하였다. 식물 화석은 모두 인상화석으로 보존되었으며 세일층의 층리면에 평행하게 밀집된 상태로 나타나지만 대부분 파편상으로 나타난다. 식물화석은 고환경이나 고생태에 대한 중요한 단서를 제공하고 과거의 기후를 알려주는 중요한 지시자로 사용되고 있다. 특히 케이로레피드과의 식물은 백악기의 대표적인 고기후의 지시자로서 잘 알려져 있다. 케이로레피드과의 식물은 분류상 구과류에 속하며 백악기에 걸쳐 세계적인 분포를 보이고 있는 화석이다. 본 연구는 영동층군에서 산출된 구과류 화석을 대상으로 고생물학적 연구를 수행하여 산출화석의 특징을 기재하고 체계적으로 분류함으로써 산출화석의 고식물학적 의미를 밝히고자 하였다. 또한 산출 화석의 특징과 지질학적 특징을 통해 중생대 백악기 영동지역의 고기후를 해석함으로써 고기후적 및 고생태학적 의미를 연구해 보고자 하였다.에서는 시스템 등급에 영향을 준다. 향후에는 더욱 더 다양한 상호의존 모델들이 정량화될 필요성이 있다고 본다. 진행하였다. 줄여서 보다 더 정확하고, 지능적인 규칙구성요소 추출 방법론을 제시하고 구현하여 지식관리자의 규칙습득에 대한 부담을 줄여 주고자 한다. 도움을 받을 수 있게 되었다.을 거치도록 되어있다. 교통주제도는 국가의 교통정책결정과 관련분야의 기초자료로서 다양하게 활용되고 있으며, 특히 ITS 노드/링크 기본지도로 활용되는 등 교통 분야의 중요한 지리정보로서 구축되고 있다..20{\pm}0.37L$, 72시간에 $1.33{\pm}0.33L$로 유의한 차이를 보였으므로(F=6.153, P=0.004), 술 후 폐환기능 회복에 효과가 있다. 4) 실험군과 대조군의 수술 후 노력성 폐활량은 수술 후 72시간에서 실험군이 $1.90{\pm}0.61L$, 대조군이 $1.51{\pm}0.38L$로 유의한 차이를 보였다(t=2.620, P=0.013). 5) 실험군과 대조군의 수술 후 일초 노력성 호기량은 수술 후 24시간에서 $1.33{\pm}0.56L,\;1.00{\ge}0.28L$로 유의한 차이를 보였고(t=2.530, P=0.017), 술 후 72시간에서 $1.72{\pm}0.65L,\;1.33{\pm}0.3L$로 유의한 차이를 보였다(t=2.540, P=0.016). 6) 대상자의 술 후 폐환기능에 영향을 미치는 요인은 성별로 나타났다. 이에 따른 폐환기능의 차이를 보면, 실험군의 술 후 노력성 폐활량이 48시간에 남자($1.78{\pm}0.61L$)가 여자($1.27{\pm}0.45L$)보다 더 높게 나타났으며 (t=2.170, P=0.042), 72시간에도 역시 남자($2.1

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Depositional Processes of Pyroclastic Density Currents in Lacustrine Environments: An Example from the Cretaceous Jeonggaksan Formation in Danjang-myeon, Miryang City (호수 내 화쇄밀도류의 퇴적과정: 밀양시 단장면 일원 백악기 정각산층의 예)

  • Gihm, Yong Sik;Park, Seung-Ik
    • Economic and Environmental Geology
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    • v.55 no.3
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    • pp.295-307
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    • 2022
  • We studied the Cretaceous Jeonggaksan Formation to determine depositional processes of pyroclastic density currents entering into the lacustrine environments. This formation is composed largely of sandstone-mudstone couplets and (tuffaceous) normally graded sandstones deposited in lacustrine environments, interbedded with two pyroclastic beds: welded massive lapilli tuff and normally graded lapilli tuff. The welded massive lapilli tuff (10 m thick) is composed of poorly sorted, structureless lapilli supported by a welded ash matrix. The normally graded lapilli tuff (4 m thick) is characterized by moderately to well sorted natures and multiple normally graded divisions in the lower part of the bed with internal boundaries. The contrasting depositional features between these lapilli tuff are suggestive of different physical characteristics and depositional processes of pyroclastic density currents in the lake. Overall poorly sorted and massive natures of the thick, welded massive lapilli tuff are interpreted to have been formed by rapid settling of pyroclastic sediments from highly concentrated and sustained pyroclastic density currents. In this case, the pyroclastic density currents were able to displace lake water from shoreline and the pyrolclastic density currents preserved their own heat except for frontal parts of the currents. As a result, welded textures can be formed despite entrance of pyroclastic density currents into the lake. The internal boundaries of the normally graded lapilli tuff reflect unsteady natures of the pyroclastic density currents at the time of the deposition and the pyroclastic density currents can not provide sufficient pressure to displace lake water. As a consequence, the pyroclastic density currents transformed into water-saturated turbidity currents, forming relatively well sorted, normally graded lapilli tuff.

Controls on Diagenetic Mineralogy of Sandstones and Mudrocks from the Lower Hayang Group (Cretaceous) in the Daegu Area, Korea (대구 부근 하부 하양층군(백악기) 사암과 이암의 속성 광물과 속성 작용의 규제 요인)

  • Shin, Young-Sik;Choo, Chang-Oh;Lee, Yoon-Jong;Lee, Yong-Tae;Koh, In-Seok
    • Journal of the Korean earth science society
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    • v.23 no.7
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    • pp.575-586
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    • 2002
  • Authigenic minerals found in sandstones and mudrocks of the Lower Hayang Group (Cretaceous) in the central part of the Kyungsang Basin are carbonate minerals (calcite, dolomite), clay minerals (illite, chlorite, C/S, I/S and kaolinite), albite, quartz and hematite. Characteristic diagenetic mineral assemblages are as follows: albite-chlorite (including C/S)-hematite in the Chilgog Formation, albite-illite-calcite in the Silla Conglomerate, illite-chlorite-hematite in the Haman Formation and albite-chlorite-dolomite in the Panyawol Formation, respectively. Among clay minerals reflecting the physical and chemical change of the diagenetic process, illite, the dominant clay mineral, occurs in every formation in the study area. Chlorite occurs mainly in green or gray sandstones and mudrocks, or in sandstones and mudrocks of the Chilogok Formation which contains a high content of volcanic materials. Based on the mineral assemblage, diagenetic minerals are strongly related with source rocks. Judging from the illite crystallinity, diagenesis of sandstones and mudrocks in the study area reached the late diagenetic stage or low grade metamorphisim. The diagenetic process was much influenced by intrusion of the Bulguksa granite, content of organic materials, grain size, and depositional environment rather than burial depth.