• Title/Summary/Keyword: 역암층

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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.

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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Linear cutting machine test for assessment of the cutting performance of a pick cutter in sedimentary rocks (퇴적층 암석의 픽 커터 절삭성능 평가를 위한 선형절삭시험)

  • Jeong, Hoyoung;Jeon, Seokwon
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.20 no.1
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    • pp.161-182
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    • 2018
  • We carried out a series of linear cutting machine tests to assess the cutting performance of a pick cutter in sedimentary rock. The specimens were Linyi sandstone from China and Concrete (rock-like material, conglomerate). Using the small scaled LCM system, we estimated the cutter force and specific energy under different cutting conditions. The cutter forces (cutting and normal) increased with penetration depth and cutter spacing in two rock types, and it was affected by the strength of specimens. On the other hand, the ratio of the peak cutter force to the mean cutter force was influenced by cutting characteristic and composition of rock rather than rock strength. The cutting coefficient was affected by the friction characteristic between rock and pick cutter rather than the cutting conditions. Therefore, the optimal cutting angle can be determined by considering of cutting coefficient and resultant force of pick cutter. The optimum cutting condition was determined from the relationship between the specific energy and cutting condition. For two specimens, the optimum s/p ratio was found to be two to four, and the specific energy decreased with the penetration depth. The result from this study can be used as background database to understand the cutting mechanism of a pick cutter, also it can be used to design for the mechanical excavator.

The Tectono-metamorphic Evolution of Metasedimentary Rocks of the Nampo Group Outcropped in the Area of the Daecheon Beach and Maryangri, Seocheon-gun, Chungcheongnam-do (충남 대천해수욕장과 서천군 마량리 지역에 분포된 남포층군 변성퇴적암층의 변성지구조 진화)

  • Song, Yong-Sun;Choi, Jung-Youn;Park, Kye-Hun
    • The Journal of the Petrological Society of Korea
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    • v.17 no.1
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    • pp.1-15
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    • 2008
  • The metasedimentary rocks of the Nampo Croup consisting of metaconglomerates, metasandstones, phyllites are exposed in the area of the Daechcon beach and Maryangri, Seocheon-gun. Their typical metamorphic assemblages of Bt-Mus-Grt-Qtz (${\pm}Pl{\pm}Chl$) and Bt-Mus-Qtz (${\pm}Pl{\pm}Chl$) indicate that they have been under intermediate P/T type metamorphism and were metamorphosed to garnet zone grade of amphibolite-facies during the Daebo Orogeny. Pressure-temperature conditions of peak metamorphism estimated from geothermobarometries are $560{\sim}595^{\circ}C$, $6.9{\sim}8.2\;kb$ respectively. The results of K-Ar biotite age determination are $143.2{\pm}3.6\;Ma$, $122.6{\pm}2.4\;Ma$ and $124.8{\pm}2.4\;Ma$ and the last two ages are considered as the results of later-stage thermal perturbation. On the bases of the formation age of Daedong Supergroup of $187{\sim}172\;Ma$ (Han et al., 2006; Jeon et al., 2007) combined with the results of this study, the hypothetical model of tectonometamorphic evolution of the study area during Daebo Orogeny is proposed. Crustal thickening resulted from folding and duplexing of thrusts in the area initiated at around 175 Ma just after sedimentation of Nampo Croup. And then rapid cooling by normal faulting due to crustal extention followed immediately after the peak metamorphism to the closure temperature of biotite.

Formation and Evolution of the Miocene Ipcheon Subbasin in Yangbuk-myeon, Gyeongju, SE Korea (한반도 남동부 경주시 양북면 마이오세 입천소분지의 형성과 발달사)

  • Seong, Changhun;Cheon, Youngbeom;Son, Moon;Sohn, Young Kwan;Kim, Jin-Seop
    • The Journal of the Petrological Society of Korea
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    • v.22 no.1
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    • pp.19-34
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    • 2013
  • The Ipcheon Subbasin is an isolated Miocene basin in SE Korea, which has the geometry of an asymmetric graben elongated in the NE-SW direction. It is in contact with basement rocks by faults and separated from adjacent Waup and Eoil basins by the basement. The strata of the basin fills have an overall homoclinal structure, dipping toward NW or WNW. The basin fills consist of Early Miocene sediments rich in dacitic volcanic and volcaniclastic deposits and Middle Miocene non-volcanic and nonmarine conglomerates intercalated with sand layers, which are distributed in the northeastern and southwestern parts of the basin, respectively. Kinematic analysis of syndepositional conjugate faults in the basin fills indicates WNW-ESE extension of the basin. These features are very similar to those of the adjacent Waup and Eoil basins, indicating that the basin extension was governed by the NE-trending northwestern border faults and that the basin experienced a propagating rifting from NE to SW. Basaltic materials, which occur abundantly in the Eoil Basin, are totally absent in the Ipcheon Subbasin. The observations of the dacitic tuff and tuffaceous mudstone in the subbasin, on slabs and under microscope, suggest that they have lithologies very similar to those of the Yondongri Tuff in the Waup Basin. The Middle Miocene non-volcanic sediments of the Waup and Eoil basins and the Ipcheon Subbasin are distributed consistently in the southwestern part of each basin. It is thus concluded that the extension of the Ipcheon Subbasin began at about 22 Ma together with the Waup Basin and was lulled during the main extension period of the Eoil Basin between 20-18 Ma. At about 17 Ma, the subbasin was re-extended due to the activation of the Yeonil Tectonic Line associated with the propagating rifting toward SW. This event is interpreted to have provided new sedimentation space for the Middle Miocene sediments in the southwestern parts of the Waup and Eoil basins and the Ipcheon Subbasin as well.

Assessment of Rocks and Alteration Information Extraction using ASTER data for Övörkhangaii Province, Mongolia (ASTER 영상자료를 활용한 몽골 오보르항가이(Övörkhangai) 일대 암상 빛 변질 정보추출의 활용가능성 평가)

  • Jeong, Yongsik;Yu, Jaehyung;Koh, Sang-Mo;Heo, Chul-Ho
    • Economic and Environmental Geology
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    • v.48 no.4
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    • pp.325-335
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    • 2015
  • This study examined the possibility to extract potential alteration zones and lithologic information based on ASTER band ratio techniques for mineralized area located in ${\ddot{O}}v{\ddot{o}}rkhangai$ province, Mongolia, and the effectiveness of remote sensing as a preliminary exploration tool for mineral exploration was tested. The results of ABRLO, PBRLO, and PrBRLO models indicated that the detection of argillic zone requires the verification of the samples to verify hydrothermal alteration minerals as clay minerals can formed by weathering process, whereas phyllic-propylitic zones were considerably related to the spatial distribution of the intrusive bodies, geological structures, and ore distribution. QI and MI results showed that QI is more useful for sedimentary rocks such as conglomerate and sandstone than meta-sedimentary like quartzite, and MI faced relatively uncertain in detection of felsic or mafic silicate rocks. QI and MI may require additional geologic information such as the characteristics of samples and geological survey data to improve extraction of lithologic information, and, if so, it is expected that remote sensing technique would contribute significantly as a preliminary geological survey method.

Nature of contact between the Ogcheon belt and Yeongnam massif and the Pb-Pb age of granitic gneiss in Cheondong-ri, Danyang (단양 천동리 지역 옥천대/영남육괴의접촌관계와 소위 화강암질 편마암의 Pb-Pb 연대)

  • 권성택;이진한;박계헌;전은영
    • The Journal of the Petrological Society of Korea
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    • v.4 no.2
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    • pp.144-152
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    • 1995
  • The Jangsan Quartzite of the Joseon Supergroup and the foliated granite (so-called granitlc gneiss of presumed Precambrian age) of the Yeongnam massif are in direct contact at Cheondong-ri area, 6 km @SE of Danyang. sllthough it has been thought traditionally that the Jangsan Quartzite overlies unconformably the f&ted granite, it is difficult to interpret the contact as an unconformity smce the basal conglomerate in- the lower part of the Jangsan Quartzite does not have any clast of the foliated granite, Rather, recent structural studies of this area indlcate that the contact is a ductile shear zone. However, the sense and age of the shear movement are still problematic. Our mesoscopic and microscopic studies of &tre Cheondong-11 semi-brittle shear zone involving foliated cataclasite and phyllonite, which is a pa& of the Ogdong fault, indlcate a top-to-the northeast shearing, i.e., dextral strike slip. We also performed Pb-Pb dating for the age-unknown foliated granite, since the age of deformed granite ccarr emtrain the maximum age of deformation. The whole rock and feldspar Pb isotape data for the foliated granite and a micaceous xenolith define an isoc chron age of $2.16{\pm}0.15$ Ga ($2{\sigma}$;MSWD=4.4) which is interpreted as the emplacement age of the granite. This early Proterozoic age agrees with those of Precambrian igneous activity In the Yeongnam massif reported previously. The obtaiPrfid gge confirms the traditional idea about the age of the foliated granite and indicates that other methd(s) should be employed to constrain the age of the shear movement.

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Petrology of the Volcanic Rocks in the Paekrogdam Crater area, Mt. Halla, Jeju Island (제주도 한라산 백록담 분화구 일대 화산암류의 암석학적 연구)

  • 고정선;윤성효;강순석
    • The Journal of the Petrological Society of Korea
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    • v.12 no.1
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    • pp.1-15
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    • 2003
  • The Paekrogdam summit crater area, Mt. Halla, Jeju Island, Korea, composed of Paekrogdam trachyte, Paekrogdam trachybasalt, and Manseidongsan conglomerate in ascending order. Joint systems show concentric and radial patterns around the summit crate wall. The Paekrogdam crater is a summit crater lake which erupted the tuffs, scorias and lava flows of Paekrogdam trachybasalt after the emplaceent of Paekrogdam trachyte dome. SiO$_2$ contents of mafic and felsic lavas are respectively, 48.0∼53.7 wt.% and 60.7∼67.4 wt.%, reflecting bimodal volcanism. And lavas with SiO$_2$ between 53.7 wt.% and 60.7 wt.% are not found. According to TAS diagram and K$_2$O-Na$_2$O diagram, the volcanic rocks belong to the normal alkaline rock series of alkali basalt-trachybasalt-basaltic trachyandesite and trachyte association. Oxide vs. MgO diagrams represent that the mafic lavas fractionated with crystallization of olivine, clinopyroxene, magnetite and ilmenite and felsic trachyte of plagioclase and apatite. The characteristics of trace elements and REEs shows that primary magma for the trachybasalt magma would have been derived from partial melting of garnet peridotite mantle. In the discrimination diagrams, the volcanic rocks are plotted at the region of within plate basalt (WPB).

A Survey Report on the Polymetallic Mineralization in the Oyon Mineralized District, Central Peru (페루 중부 오욘 다중금속 광화작용에 대한 조사보고)

  • Lee, Jaeho;Kim, Injoon;Nam, Hyeong-tae
    • Economic and Environmental Geology
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    • v.50 no.1
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    • pp.73-83
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    • 2017
  • The surveyed mines are located in a polymetallic vein, replacement, and skarn mineral district in the central Andes of Peru. Iscaycruz, which includes underground and open pit mines that produce zinc and lead concentrates, was the largest mineral deposit of an important group of base metal deposits in the Andes of central Peru. The deposits are sub-vertical seams of polymetallic ores(Zn, Cu, and Pb). These seams are hosted by Jurassic and Cretaceous sedimentary rock formation. The intrusion of igneous rocks in these formations originated metallic deposits of metasomatic and skarn types. The Raura mine is composed of polymetallic deposit of veins and replacement orebodies. The main sedimentary unit in the area is Cretaceous Machay Limestone. The Raura depression contains several orebodies each with different mineralization: predominantly Pb-Zn bearing Catuvo orebody; Ag-rich galena-bearing Lake Ninacocha orebody; Cu-Ag bearing Esperanza and Restauradora orebody. Huaron is a hydrothermal polymetallic deposit of silver, lead, zinc, and copper mineralization hosted within structures likely related to the intrusion of monzonite dikes, principally located within the Huaron anticline. Mineralization is encountered in veins parallel to the main fault systems, in replacement bodies known as "mantos" associated with the calcareous sections of the conglomerates and other favourable stratigraphic horizons, and as dissemination in the monzonitic intrusions at vein intersections.

Diversity of the Cretaceous basaltic volcanics in Gyeongsang Basin, Korea (경상분지내 백악기 현무암질 화산암류의 다양성)

  • 김상욱;황상구;이윤종;고인석
    • The Journal of the Petrological Society of Korea
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    • v.9 no.1
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    • pp.1-12
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    • 2000
  • The Cretaceous basaltic rocks in Gyeongsang Basin are temporally and spatially dispersed widely in thick sedimentary piles: Chilgog basaltic rock (CGB) and Cheongyongsa basaltic rock (CSB) in the Shindong Group, and Hakbong basaltic rocks (HBB), Osibbong basalt (OSB), Secheondong basaltic rocks (SCB), Haman basaltic rocks (HAB), Hama basaltic rocks (HMB), and Chaeyaksan basaltic rocks (CYB) in the Hayang Group, upwardly in their stratigraphy. Chilgog basaltic rock is merely identified as pebbles in the Shilla Conglomerate and its provenance has not been found, and it is characteristics that the volcanics except Osibbong basalt and Chaeyaksan basaltic rocks are very small in both of their thickness and extension. Petrochemical diversity of the basaltic rocks are revealed; OSB and SCB distributed in the Yeongyang Minor Basin preserve the calc-alkaline natures in major and immobile minor element geochemistry, but CGB, HBB, HAB, and CYB reflect that they might be originated from calc-alkaline basaltic magma of volcanic arc in continental margin area by trace elements and altered to alkaline suites in the viewpoint of their major element geochemistry. Major and trace element geochemistry of CSB and HMB suggests that they may be derived from within -plate alkaline magma contaminated by the upper continental crust, especially in the case of the former.

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