• Title/Summary/Keyword: 지질단면도

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Geological Heritage Value and Appropriate Conservation/Utilization of the Seokgaejae Early Paleozoic Sedimentary Stratal Section (석개재 전기 고생대 퇴적층 단면의 지질유산적 가치와 보전 및 활용방안)

  • Lee, Seung-Bae
    • Korean Journal of Heritage: History & Science
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    • v.50 no.3
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    • pp.126-145
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    • 2017
  • The Seokgaejae section is located along a timber access road and a driveway across Bonghwa County, North Gyeongsang Province, and Samcheog city, Gangwon Province. Its stratigraphic column shows all of the ten strata of the lower Paleozoic Taebaek Group, Joseon Supergroup. The Seokgaejae section is proved to be scientifically important. Thirty-eight domestic/international journal papers have been published on this early Paleozoic stratigraphic site, and many distinguished researchers over the world have visited the site. However, the section has never been considered to be designated as a national natural monument and was not included in the adjacent Gangwon Paleozoic National Geopark due to management or administrative issues. Although the Seokgaejae section sufficiently satisfies many of the national natural monument criteria, designation for the natural monument may not be justified because of the facts that the outcrop was artificially exposed by road construction; the chance of destruction of the outcrop is relatively few; demage on the outcrop to some extent does not impair the intrinsic value of the section; and the geomorphological/landscape value of the section is low. The application of the recently modified geological heritage assessment model to the Seokgaejae section shows very high scores on the scientific/educational, intrinsic, and functional values. Based on the improved geological heritage grade standard, the Seokgaejae section conforms to the national-level protection criteria. It is strongly recommended to manage the Seokgaejae section as a principal geosite by including it in the Gangwon Paleozoic National Geopark. This case study on the Seokgaejae section also suggests that the process of application and endorsement of a national geopark need further improvement. As well as the improvement of the system or policy related to geological heritages, further efforts of the experts in various fields of geoscience are required in order for other geological heritages not to be neglected from now on.

Constructing Geological Cross-sections at Depth and Interpreting Faults Based on Limited Shallow Depth Data Analysis and Core Logging: Southern Section of the Yangsan Fault System, SE Korea (제한된 천부자료와 시추코어분석을 통한 심부지질단면도 작성과 단층 인지법: 한반도 남동부 양산단층대 주변에서의 적용)

  • Kim, Taehyung;Kim, Young-Seog;Lee, Youngmin;Choi, Jin-Hyuck
    • The Journal of Engineering Geology
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    • v.26 no.2
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    • pp.277-290
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    • 2016
  • Deep geological cross-sectional data is generally not common nor easy to construct, because it is expensive and requires a great deal of time. As a result, geological interpretations at depth are limited. Many scientists attempt to construct geological cross-sections at depth using geological surface data and geophysical data. In this paper, we suggest a method for constructing cross-sections from limited geological surface data in a target area. The reason for this study is to construct and interpret geological cros-sections at depth to evaluate heat flow anomaly along the Yangsan fault. The Yangsan Fault passes through the south-eastern part of the Korean Peninsula. The cross-section is constructed from Sangbukmyeon to Unchonmyeon passing perpendicularly through the Yangsan Fault System trending NW-SE direction. The geological cross-section is constructed using the following data: (1) Lithologic distributions and main structural elements. (2) Extensity of sedimentary rock and igneous rock, from field mapping. (3) Fault dimension calculated based on geometry of exposed surface rupture, and (4) Seismic and core logging data. The Yangsan Fault System is composed of the Jain fault, Milyang fault, Moryang fault, Yangsan fault, Dongnae fault, and Ingwang fault which strike NNE-SSW. According to field observation, the western section of the Yangsan fault bounded by igneous rocks and in the eastern section sedimentary rocks are dominant. Using surface fault length we infer that the Yangsan Fault System has developed to a depth of kilometers beneath the surface. According to seismic data, sedimentary rocks that are adjacent to the Yangsan fault are thin and getting thicker towards the east of the section. In this study we also suggest a new method to recognize faults using core loggings. This analysis could be used to estimate fault locations at different scales.

P-Impedance Inversion in the Shallow Sediment of the Korea Strait by Integrating Core Laboratory Data and the Seismic Section (심부 시추코어 실험실 분석자료와 탄성파 탐사자료 통합 분석을 통한 대한해협 천부 퇴적층 임피던스 도출)

  • Snons Cheong;Gwang Soo Lee;Woohyun Son;Gil Young Kim;Dong Geun Yoo;Yunseok Choi
    • Geophysics and Geophysical Exploration
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    • v.26 no.3
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    • pp.138-149
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    • 2023
  • In geoscience and engineering the geological characteristics of sediment strata is crucial and possible if reliable borehole logging and seismic data are available. To investigate the characteristics of the shallow strata in the Korea Strait, laboratory sonic logs were obtained from deep borehole data and seismic section. In this study, we integrated and analyzed the sonic log data obtained from the drilling core (down to a depth of 200 m below the seabed) and multichannel seismic section. The correlation value was increased from 15% to 45% through time-depth conversion. An initial model of P-wave impedance was set, and the results were compared by performing model-based, band-limited, and sparse-spike inversions. The derived P-impedance distributions exhibited differences between sediment-dominant and unconsolidated layers. The P-impedance inversion process can be used as a framework for an integrated analysis of additional core logs and seismic data in the future. Furthermore, the derived P-impedance can be used to detect shallow gas-saturated regions or faults in the shallow sediment. As domestic deep drilling is being performed continuously for identifying the characteristics of carbon dioxide storage candidates and evaluating resources, the applicability of the integrated inversion will increase in the future.

Estimation of Joint Roughness Coefficient(JRC) using Modified Divider Method (수정 분할자법을 이용한 절리 거칠기 계수(JRC)의 정량화)

  • Jang Hyun-Shic;Jang Bo-An;Kim Yul
    • The Journal of Engineering Geology
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    • v.15 no.3
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    • pp.269-280
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    • 2005
  • We assigned points on surface of standard roughness profile by 0.1mm along the length and measured coordinates of points. Then, the lengths of profile were measured with different scales using modified divider method. The fractal dimensions and intercepts of slopes were determined by plotting the length vs scale in log-log scale. The fractal dimensions as well as intercepts of slopes show well correlation with joint roughness coefficients(JRC). However, multiplication of the kactal dimension by intercept show better correlation with IRC and we derived a new equation to estimate JRC from fractal dimension and intercept. The crossover length in which we can determine the correct fractal dimension was between 0.3-3.2mm. We measured joint roughness of 26 natural joints and calculated JRC using the equation suggested by Tse and Cruden(1979) and new equation derived by us. IRC values calculated by both equations are almost the same, indicating new equation is effective in measuring IRC.

Geological Approach for Use Interpretation of a Cultural Heritage Site at Gochon-ri, Busan (부산 고촌지구 문화유적지의 용도해석을 위한 지질학적 접근)

  • Lee, Min-Joo;Han, Seung-Rok;Paik, In-Sung;Kim, Young-Seog
    • The Journal of Engineering Geology
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    • v.19 no.3
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    • pp.373-387
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    • 2009
  • Many cultural heritages with various periods including the 'Three Kingdoms Period' were discovered in Chulmamyeon, Busan. Detailed geomorphological and geological investigation was performed due to archaeological importance of the study area. Aerial photographic analysis for geomorphology and analysis of vertical sedimentary sections to interpret the sedimentary characteristics were carried out. Many pebbles with specific features were discovered during the investigation. The characteristics and origin of the pebbles are analysed based on their size, rock type and shape. The study area is located in a relatively low and gentle slope compared with neighboring regions. The strong N-S trending lineaments may influence the topographic features and the distribution of wells discovered in this area. The exposed sections during excavation are divided into several layers depending on colors and materials included. Some of the layers may be developed not by nature but by human activities. The similarity of the pebbles indicates that these pebbles may artificially be collected or produced for a specific purpose. This study shows that geomorphology and geology can be important in location and development of archaeological sites. The analysis and interpretation for the origin of the pebbles indicates that geological studies can be helpful to interpretation of archaeological studies.

Conical Slope Stability of Tertiary Basalt Based on the Geological Cross-Sections (지질횡단면을 활용한 원추형 현무암 비탈면 안정성)

  • Myeong-Hyeok Ihm;Sung-Pil Hwang;Byung-Suk Park;Jun-Sang An;Woo-Seok Kim
    • The Journal of Engineering Geology
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    • v.34 no.3
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    • pp.447-457
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    • 2024
  • This study investigated a cut-slope surface containing Tertiary faults, representing a conical-shaped slope with strike varying from N44°E to NS, N50°W, and finally N70°E. The slope consists mainly of basalt, with discontinuities in the slope including faults, fault zones, fracture zones, shear joints, and extension joints. The type and scale of failure vary with the strike of the slope and the strikes of discontinuities, with plane and wedge failure predominating. Based on face-mapping data, SMR (slope mass rating), rock physical and mechanical properties, analysis of stereonet projections and geological cross-sections, and critical equilibrium analysis, optimal slope stability determination was found to involve the countermeasure method, the slope gradient relief method, the green soil surface treatment method, and a fall prevention measure. After application of the countermeasure method, both dry and wet slope conditions exceeded allowable safety factors. It is expected that the preparation of geological cross-sections of various representative sections perpendicular to the surface of the slope, and the application of corresponding countermeasure methods, will be reasonable tools for three-dimensional analysis of slope stability. If the strike of the slope varies widely, it is necessary to prepare geological cross-sections, and the section used for critical equilibrium analysis must be established as the basic section.