• Title/Summary/Keyword: geologic outcrop

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A Measure on the Conservation of Geological Heritages : Geological Survey and Evaluation Forms for Geologic Outcrops (지질유산 보전방안 : 지질노두 조사표와 평가표의 작성과 활용)

  • Sagong, Hee;Lee, Soo-Jae
    • The Journal of the Petrological Society of Korea
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    • v.23 no.2
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    • pp.145-152
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    • 2014
  • Geological heritages can be defined conveniently as geological records worthy of conservation, and are represented in most cases by geological outcrops. So survey and evaluation of geologic outcrops are necessary for better conservation of geological heritages. As a measure to prevent potential destruction of geological heritages from various development projects, I propose construction of database based on survey and evaluation forms of geological outcrop, which can also be used for environmental impact assessment. The geological survey form consists of survey area, category, subcategory, location, dimension, geologic features, photo, description, and investigator. The evaluation form consists of evaluation category, detailed evaluation, comprehensive evaluation, and evaluation grade. The evaluation category is divided into academic aspect, education effect and landscape. The detailed evaluation items for academic aspects and education effect are representativeness, rarity, diversity and typicality, while those for geomorphology and landscape are peculiarity, aesthetics and naturalness. The evaluation grades are divided into five, where the first grade means a must of conservation.

Fusulinids from the Carboniferous strata in the Gangdong area of Samcheok coalfield, Korea

  • Lee, Chang-Zin;Kim, Jun-Ho;Lee, Sang-Min
    • Journal of the Korean earth science society
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    • v.27 no.7
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    • pp.768-777
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    • 2006
  • The goal of this study is to elucidate the fusulinid biostratigraphy of the Carboniferous limestones distributed in the Gangdong area of Samcheok coalfield, Korea. The Carboniferous strata of the study area mainly comprise alternaton of dark gray shale, dark gray and reddish sandstone, and gray limestone. The limestones consist mainly of wackestonepackstone containing various fossil fragments such as crinoid, coral, brachiopod, foraminifera, fusulinid, and bryozoa; this observation thus suggests that the study site was the shallow marine environments. A tital of 12 species belonging to 5 genera of fusulinids are identified from the limestones of the Gangdong geologic section: Ozawainella turgida Sheng, Ozawainella sp. A, Ozawainella magna Sheng, Pseudostaffella antiqua (Dutkevich), Pseudostaffella paracompressa Safonova, Pseudostaffella kimi Cheong, Pseudostaffella sp., Beedeina lanceolata (Lee and Chen), Beedeina samarica (Rauser-Chernoussova), Beedeina sp. A, Neostaffella sphaeroidea cuboides Rauser-Chernoussova, and Hanostaffella hanensis Cheong. Such fusulinids species were reported from the lower part of the Geumcheon Formation in Samcheok coalfield and the middle Moscovian stage in Eurasia. On the basis of the fusulinid biostratigraphic correlation of the Gangdong geologic sections (A) to (C), the limestone should be overlapped by faults and folds. Moreover the stratigraphic thickness of the limestone is thinner than the thickness of the limestone outcrop of the Gangdong geologic section. Therefore, the stratigraphic sequence of the Gangdong geologic section is represented as the Gangdong geologic section (A).

Development of Learning Place for Geologic Field Survey around the Duta Mountain, Chungbuk, Korea (충북 괴산군 두타산 일대의 야외지질조사 학습장 개발)

  • Lee, Chang-Xin;Cheong, Sang-Won
    • Journal of the Korean earth science society
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    • v.26 no.1
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    • pp.41-57
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    • 2005
  • The purpose of the study is to develop a educational data in order for students to perform geologic field survey effectively by themselves. A area around the Duta Mountain is selected. which is located at the southeastern part of Eumsung sedimentary basin because various rock types and geologic structures are well shown in this area and also it is convenient to reach there. Thirteen stops for observation are chosen m a route f3r exercising field geologic investigation. Data for field research are given and described in detail from each stop for observation. To do this, students make their own route map using general or digital geographic map and aerial photo is added to know relationship between large-scale structure and different rock types regionally. Moreover, it is designed to minimize conflict factors that may be experienced from the real field survey by showing outcrop photographs and polarizing photomicrographs of rut samples related to each stop and geologic structures. The attitude of students is investigated with the data of field geologic survey for students of an Earth Science class in the College of Education in Chungbuk National University. The results indicate that the educational data for geologic field survey brought positive changes that greatly help students perform field survey in definitive side, especially formation of absolute concepts on earth science.

Determination of the latest fault movement by trench survey at Galgok-Chisil site in the northern Ulsan fault system (울산단층북부 갈곡리 치실 지점의 마지막 단층 운동시기 결정)

  • Choi, Weon-Hack;Chang, Chun-Joong;Inoue, D.;Tanaka, T.
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2005.03a
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    • pp.11-17
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    • 2005
  • Along the Ulsan Fault System, many Quaternary faults have been reported and investigated with outcrop observation and trench excavation to clarify the neotectonic movements and fault parameters such as length, displacement, slip rate and recurrence interval. In the northern part of the Ulsan fault system, we have interpreted small scale(1:10,000) aerial photographs and extracted lineaments by geomophological features to select trench site. After precise field survey and tracing for lineaments, two trench sites at Galgokri, Gyeongju were selected on the lineament to elucidate the fault movement history. One is successful in finding faults but the other is not. In the Galgok-Chisil trench(3m(w) x 1.5m(d) x 10m(l)), very closed two Quaternary faults cut the alluvial deposits of which age shows about 10-3ka. More than three times of fault movements can be inferred by geologic structures and C-14 dating. Repeatedly fault movements had been occurred before 10 ka, between 10ka-4.9 ka, between 4.9-1.4 ka at Galgok-Chisil trench section.

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Characteristics of Rainfall, Geology and Failure Geometry of the Landslide Areas on Natural Terrains, Korea (우리나라 자연사면 산사태지역의 강우, 지질 및 산사태 기하형상 고찰)

  • Kim, Won-Young;Chae, Byung-Gon
    • The Journal of Engineering Geology
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    • v.19 no.3
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    • pp.331-344
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    • 2009
  • Large landslides occurred since 1990 on natural terrain, Korea were reviewed with the existing data to characterize them in terms of the condition of rainfall, geology and geometry. Ten landslide areas over the nationwide are selected for this study. Among them, five areas consist of granite basement, four areas of granite and metamorphic rocks and the remaining an area of gabbro. The basement lithology on which landslides most dominantly occurred is granite, on which 58% of landslides among the total 3,435 are taken place, the next dominant one is metamorphic rocks where 24% of landslides are occurred, and the remaining 18% are on the areas of volcanic and sedimentary rocks which are partly distributed in some areas. The landslide occurrences may depend on the rainfall intensities rather than durations. We applied the theories of Caine's threshold and Olivier's final response coefficient to the Korean cases. The rainfall conditions at the landslide areas were all satisfied enough with the landslide triggering conditions suggested by Caine and Olivier. The triggering mechanism and type of landslides may largely depend on the weathering and geomorphic characteristics of basement lithology. The granite areas are characterized by being relatively shallow but consistent weathering profiles and almost no outcrop, and therefore, shallow translational slides are dominant. Whereas metamorphic areas are characterized by consisting of steep slope, weathered outcrops on ridges and partly on flanks and irregular weathering profiles, and relatively large debris flows are dominant.

Comparative Study of Square-Inventory Method with Scanline Survey in Slope Stability Analysis (사면 안정 분석을 위한 정면적법과 선조사법의 비교연구)

  • Cheong, Sang-Won;Choi, Byoung-Ryol
    • The Journal of Engineering Geology
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    • v.19 no.2
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    • pp.119-129
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    • 2009
  • In relation to slope stability analysis, geologic characteristics and engineering properties of the discontinuities in three slopes selected are compared and analyzed by both square-inventory method and scanline survey. The aim of the study is in evaluating which method is applied better in slope stability analysis by comparing results of the two methods with those of direct observation on outcrop of slope failures generated. In each slope, results of comparative analysis among geologic and engineering properties are analyzed similarly one another. However, results of orientation analysis in slope 2 are different each other, which indicates orientation of joints in slope 2 depends on persistency and frequency of each joint and also indicates appearance of new joint set with different orientation. Probability density distribution and spacing in slope 3 are high in comparison to those in slope 2 and 3. The reasons are that distribution of psammitic rocks and development of minor folds in slope 3 unlike slope 2 and 3 are closely associated with development of joints. The research data indicate that the square-inventory method predicts more precise failure aspects and is more effective way than scanline survey in analyzing slope stability of the study area.

Evaluation of Earthquake Ground Motion Considering Dynamic Site Characteristics in Korea (국내 지반특성에 적합한 설계지반운동 결정 방법에 대한 연구)

  • Yoon, Jong-Ku;Kim, Dong-Soo
    • Journal of the Earthquake Engineering Society of Korea
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    • v.8 no.3
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    • pp.23-32
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    • 2004
  • The local geologic and dynamic site characteristics, which include soil profiles, shear wave velocity profiles and depths to the bed rock were gathered from 148 sites all over the Korean peninsula and those values are compared to those in the western USA. Site response analyses were performed based on equivalent linear scheme using design rock-outcrop acceleration of 0.154g which corresponds to the collapse level of earthquake for seismic category I structure. The results show that the amplification factor based on Korean seismic design guideline underestimates the motion in short-period range and overestimates the motion in mid-period range. It is suggested that the existing Korean seismic guideline based on UBC is required to be modified considering dynamic site characteristics in Korea for the reliable estimation of site amplification.

Development of Site Classification System and Modification of Site Coefficients in Korea Based on Mean Shear Wave Velocity of Soil and Depth to Bedrock (기반암 깊이와 토층 평균 전단파속도를 이용한 국내 지반분류 방법 및 지반 증폭계수 개선)

  • Kim, Dong-Soo;Lee, Sei-Hyun;Yoon, Jong-Ku
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.1C
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    • pp.63-74
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    • 2008
  • Site response analyses were performed based on equivalent linear technique using the local geologic and dynamic site characteristics, which include soil profiles, shear wave velocity profiles and depth to bedrock for 125 sites collected in Korean Peninsula. From the results of site response analyses, 2-parameters site classification system based on the combination of mean shear wave velocity of soil and depth to bedrock was newly recommended for regions of shallow bedrock depth in Korea. First, as the borders of bedrock depth (H) for site classification were determined as 10m and 20m, the soil sites were divided into 3 classes as $H_1$, $H_2$ and $H_3$ sites. And then, the 3 site classes were subdivided into 7 classes based on the mean shear wave velocity of soil ($V_{s,soil}$). The feasibility of new site classification system was verified and the representative site coefficients ($F_a$ and $F_v$) and design response spectrum were suggested by analyzing uniform trend and dispersion of site coefficients for each site class. The suggested site coefficients and the regression curves present the nonlinear characteristics of soils according to the change of rock outcrop acceleration with uniform trend effectively. From the comparison between the mean values of response spectrum which was acquired from the site response analysis and the suggested design response spectrum, there was a little difference in some of site classes and it was verified to adjust the integration interval to make it more suitable for the site condition in Korea.

Characteristics and Distribution Pattern of Carbonate Rock Resources in Kangwon Area: The Gabsan Formation around the Mt. Gachang Area, Chungbuk, Korea (강원 지역에 분포하는 석회석 자원의 특성과 부존환경: 충북 가창산 지역의 갑산층을 중심으로)

  • Park, Soo-In;Lee, Hee-Kwon;Lee, Sang-Hun
    • Journal of the Korean earth science society
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    • v.21 no.4
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    • pp.437-448
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    • 2000
  • The Middle Carboniferous Gabsan Formation is distributed in the Cheongrim area of southern Yeongwol and the Mt. Gachang area of Chungbuk Province. This study was carried out to investigate the lithological characters and geochemical composition of the limestones and to find out controlling structures of the limestones of the formation. The limestones of the Gabsan Formation are characterized by the light gray to light brown in color and fine and dense textures. The limestone grains are composed of crinoid fragments, small foraminfers, fusulinids, gastropods, ostracods, etc. Due to the recrystallization, some limestones consist of fine crystalline calcites. The chemical analysis of limestones of the formation was conducted to find out the contents of CaO, MgO, Al$_2$O$_3$, Fe$_2$O$_3$ and SiO$_2$. The content of CaO ranges from 49.78-60.63% and the content of MgO ranges from 0.74 to 4.63% The contents of Al$_2$O$_3$ and Fe$_2$O$_3$ are 0.02-0.55% and 0.02${\sim}$0.84% , respectively. The content of SiO$_2$ varies from 1.55 to 4.80%, but some samples contain more than 6.0%. The limestones of the formation can be grouped into two according to the CaO content: One is a group of which CaO content ranges from 49.78 to 56.26% and the other is a group of which CaO content varies from 59.36 to 60.38%. In the first group, the contents of Al$_2$O$_3$, Fe$_2$O$_3$ and SiO$_2$ range very irregularly according to the CaO content. In the second group, the values of MgO, Al$_2$O$_3$, Fe$_2$O$_3$ and SiO$_2$ are nearly same. Detailed structural analysis of mesoscopic structures and microstructures indicates the five phase of deformation in the study area. The first phase of deformation(D$_1$) is characterized by regional scale isoclinal folds, and bedding parallel S$_1$ axial plane foliation which is locally developed in the mudstone and sandstone. Based on the observations of microstructures, S$_1$ foliations appear to be developed by grain preferred orientation accompanying pressure-solution. During second phase of deformation, outcrop scale E-W trending folds with associated foliations and lineations are developed. Microstructural observations indicate that crenulation foliations were formed by pressure-solution, grain boundary sliding and grain rotation. NNW and SSE trending outcrop scale folds, axial plane foliations, crenulation foliations, crenulation lineations, intersection lineations are developed during the third phase of deformation. On the microscale F$_3$ fold, axial plane foliations which are formed by pressure solution are well developed. Fourth phase of deformation is characterized by map scale NNW trending folds. The pre-existing planar and linear structures are reoriented by F$_4$ folds. Fifth phase of deformation developed joints and faults. The distribution pattern of the limestones is mostly controlled by F$_1$ and F$_4$ folds.

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한강하류지형면의 분류와 지형발달에 대한 연구 (양수리에서 능곡까지)

  • Park, No-Sik
    • Journal of the Speleological Society of Korea
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    • no.68
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    • pp.23-73
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    • 2005
  • Purpose of study; The purpose of this study is specifically classified as two parts. The one is to attempt the chronological annals of Quaternary topographic surface through the study over the formation process of alluvial surfaces in our country, setting forth the alluvial surfaces lower-parts of Han River area, as the basic deposit, and comparing it to the marginal landform surfaces. The other is to attempt the classification of micro morphology based on the and condition premising the land use as a link for the regional development in the lower-parts of Han river area. Reasons why selected the Lower-parts of Han river area as study objects: 1. The change of river course in this area is very serve both in vertical and horizontal sides. With a situation it is very easy to know about the old geography related to the formation process of topography. 2. The component materials of gravel, sand, silt and clay are deposited in this area. Making it the available data, it is possible to consider about not oかy the formation process of topography but alsoon the development history to some extent. 3. The earthen vessel, a fossil shell fish, bone, cnarcoal and sea-weed are included in the alluvial deposition in this area. These can be also valuable data related to the chronological annals. 4. The bottom set conglometate beds is also included in the alluvial deposits. This can be also valuable data related to the research of geomorphological development. 5. Around of this area the medium landform surface, lower landform surface, pediment and basin, are existed, and these enable the comparison between the erosion surfaces and the alluvial surfaces. Approach : 1. Referring to the change of river beds, I have calculated the vertical and horizontal differences comparing the topographic map published in 1916 with that published in 1966 and through the field work 2. In classifying the landform, I have applied the method of micro morphological classification in accordance with the synthetic index based upon the land conditions, and furthermore used the classification method comparing the topographic map published in 1916 and in that of 1966. 3. I have accorded this classification with the classification by mapping through appliying the method of classification in the development history for the field work making the component materials as the available data. 4. I have used the component materials, which were picked up form the outcrop of 10 places and bored at 5 places, as the available data. 5. I have referred to Hydrological survey data of the ministry of Construction (since 1916) on the overflow of Han-river, and used geologic map of Seoul metropolitan area. Survey Data, and general map published in 1916 by the Japanese Army Survbey Dept., and map published in 1966 by the Construction Research Laboratory and ROK Army Survey Dept., respectively. Conclusion: 1. Classification of Morphology: I have added the historical consideration for development, making the component materials and fossil as the data, to the typical consideration in accordance with the map of summit level, reliefe and slope distribution. In connection with the erosion surface, I have divided into three classification such as high, medium and low-,level landform surfaces which were classified as high and low level landform surfaces in past. furthermore I have divided the low level landform surface two parts, namely upper-parts(200-300m) and bellow-parts(${\pm}100m$). Accordingly, we can recognize the three-parts of erosion surface including the medium level landform surface (500-600m) in this area. (see table 22). In condition with the alluvial surfaces I have classified as two landform surfaces (old and new) which was regarded as one face in past. Meamwhile, under the premise of land use, the synthetic, micro morphological classification based upon the land condition is as per the draw No. 19-1. This is the quite new method of classification which was at first attempted in this country. 2. I have learned that the change of river was most severe at seeing the river meandering rate from Dangjung-ni to Nanjido. As you seee the table and the vertical and horizontal change of river beds is justly proportionable to the river meandering rate. 3. It can be learned at seeing the analysis of component materials of alluvial deposits that the component from each other by areas, however, in the deposits relationship upper stream, and between upper parts and below parts I couldn't always find out the regular ones. 4. Having earthern vessel, shell bone, fossil charcoal and and seaweeds includen in the component materials such as gravel, clay, sand and silt in Dukso and Songpa deposits area. I have become to attempt the compilation of chronicle as yon see in the table 22. 5. In according to hearing of basemen excavation, the bottom set conglomerate beds of Dukso beds of Dukso-beds is 7m and Songpa-beds is 10m. In according to information of dredger it is approx. 20m in the down stream. 6. Making these two beds as the standard beds, I have compared it to other beds. 7 The coarse sand beds which is covering the clay-beds of Dukso-beds and Nanjidobeds is shown the existence of so-called erosion period which formed the gap among the alluvial deposits of stratum. The former has been proved by the sorting, bedding and roundness which was supplied by the main stream and later by the branch stream, respectively. 8. If the clay-beds of Dukeo-bed and Songpa-bed is called as being transgressive overlap, by the Eustatic movement after glacial age, the bottom set conglomerate beds shall be called as being regressive overlap at the holocene. This has the closest relationship with the basin formation movement of Seoul besides the Eustatic movement. 9. The silt-beds which is the main component of deposits of flood plain, is regarded as being deposited at the Holocene in the comb ceramic and plain pottery ages. This has the closest relationship with the change of river course and river beds.