• Journal of Korean Society of Forest Science
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• v.79 no.4
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• pp.367-375
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• 1990

In order to determine the effects of bedrock, organic matter, calcium and iron oxide on the soil aggregation, this research has performed with soils from bedrock regions of Limestone, Granite and Granite gneiss. This research was also to estimate how organic matter, calcium and iron oxide influence on soil aggregation under different forest conditions in various bedrock regions. And it also had a purpose to rate physical factors relevant to soil aggregation, their characteristics and aggregate diameter which closely relates to stabilities in the process of soil erosion. The following conclusions have been drawn in response to the overall research objectives. The rates of the soil aggregation on different bedrock regions were 21% in Limestone bedrock, 19.8% in Granite bedrock and 9.9% in Granite gneiss bedrock. A main factor in soil aggregation was the orgainc matter content in soils and the rate of soil aggregation increased in the constant proportion with the organic matter content. The relation could be formulated into Y=4.31X-4.37(Y : aggregation ratio X : organic matter content). The soil aggregation ratio under the deciduous forests eras higher than that under the coniferous forests. It was considered that this resulted from differences in organic matter content. Soil aggregates with larger diameter than 0.5mm were found more in Limestone bedrock than other smaller size soil aggregates of 0.25mm diameter were more distributed in Granite gneiss bedrock. Granite bedrock region had normal distribution in soil aggregate sizes with the highest frequency of 0.5mm diameter. Calcium and iron oxides had only partial influences on the soil aggregation in some specific conditions. But in Limestone bedrock region calcium influenced on the soil aggregation with the organic matter content.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.3
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• pp.139-144
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• 2000

This study was conducted to obtain the basic information to increase the practical use of soil survey data through the subdividing of valley shapes with soil sequences due to different parent rocks, and to study the relationship between the valley shapes and parent rock. The various rocks such as sedimentary(gray shale and sand stone) and igneous rocks(granite, granite gneiss and andesite porphyry) which are the major parent rocks in Yeongnam area were investigated. The characteristics of valleys formed and the kinds of soils derived from different rocks were analysed by using aerial photographs and topographical maps scaled 1:5,000. The rill density in igneous rock area was as high as 40. But the rill bifurcation ratio of first order stream was higher in the sedimentary than the igneous rocks except granite area. The mean slope of valleys in igneous areas was about 8%, which was higher than that of the sedimentary areas. The variability of valley width in the complexly metamorphosed rock, such as granite gneiss, and andesite porphyry, was greater than in sedimentary and in granite rocks. Based on the variability of valley widths and valley slopes, it was possible to classify the valleys into two types. The "Uterus-shaped valleys" had wide variability of valley width and were located in the areas of granite gneiss and andesite porphry rocks. while the "Roots-shaped valleys" had narrow variability of valley width and were located in the sedimentary areas. "Uterus-shaped valleys" were typified by having land forms of mountain foot slopes and alluvial fans, and the soil drainage sequences also had complexities. So that, we concluded that the variability of valley width and valley slopes was associated with kinds of parent rocks and metamorphism which influences soil sequence and characteristics.

• Economic and Environmental Geology
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• v.22 no.4
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• pp.355-370
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• 1989

Igneous rocks of study area consist of Pre-Cambrian orthogneiss, Devonian granite, Triassic foliated granites and Jurassic granites distributed along the southeast margin of Ogcheon Geosynclinal belt(SE-zone), and irregular shaped granitic stocks in the central part of the belt(C-zone). Anorthosite and gaabbro are also present in southern part of the SE-zone in the belt and intruded into gneiss complex of Ryongnam massif. Distribuition of foliated granites shows three linear arrangements which are composed of hornblende-biotite foliated granodiorite, porphyritic foliated granodiorite, biotite foliated granodiorite, leuco foliated granite and two mica foliated granite. Foliated granites generated by dextral strike slip movement at deep level. Jurassic granites composed of several rock facies are considered to be formed by differentiation of magma during Daebo Orogeny. A general trend of the chemical composition of these igneous rocks in study area suggests that most of them corresponding to calc-alkaline rock series was affected under orogeny and I-type granite except for two mica foliated granite. In chondrite normalised REE pattern of these igneous rocks, LREE shows more variable range and strong (-)Eu anomaly than HREE. Geochronological episodes of igneous activity from early Proterozoic to Cretaceous in SE-zone of Ogcheon Geosynclinal belt are two more Pre-Cambrian Orogeny, Devonian Orogeny(Variscan), Songrim Disturbance, Daebo Orogeny and Bulkuksa Disturbance.

• The Journal of Engineering Geology
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• v.21 no.3
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• pp.239-246
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• 2011

Upon encountering weathering soil at a construction site, it may be necessary to change the design and construction plans for geotechnical structures. When weathering soil is exposed to air, the weathering process proceeds rapidly, resulting in significant damage to geotechnical structures, particle defects, and an increase in moisture sensitivity. The management of weathering-soil compaction is challenging. Because the engineering properties of weathering-soils vary regionally, it is important to report the result of research into the regional characteristics of such soils. At two locations of granite gneiss in the Gansung area of Gangwon-do, geological studies were performed at 22 and 8 sites, respectively. At each site, test samples were collected for analysis by XRD and to measure particle size, consistency, and compaction. To evaluate the suitability of the material for road subgrade, we examined the interrelationship between CBR value and the uniformity coefficient, the 200 sieve passing ratio and the aggregate ${\geq}$ 2 mm) content. We found that for the weathered granite soil, aggregate sized > 2 mm has a significant effect on the CBR value. In addition, the mixing of aggregate sized > 2 mm with sub-quality soil improves the soil condition.

• Journal of the Korean earth science society
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• v.26 no.7
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• pp.674-682
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• 2005

The Samsung mine is located in Jeongsan-myeon, Cheongyang-gun, Chungcheongnam-do, and is produces sericite ores. The purpose of this study is to investigate the geology and mineralogy of sericite one and its host-rock together with the alteration processes and age of sericitization. Geological survey, polarizing microscopy, X-ray powder diffraction, electron microprobe analysis, X-ray fluorescent analysis, differential thermal analysis, and K/Ar isotope study have been employed for this study. The mine area is composed of Precambrian granite-gneiss and mica schist, and also Jurassic biotite granite. Serictization has occured within the granite-gneiss, and is interpreted to be formed by hydrothermal alteration. The sericite was formed by the breakdown of orthoclase, plagioclase, and biotite, respectively. With sericitization intensity increase, $SiO_2\;and\;Na_2O$ contents are decreased, while $Al_2O_3\;and\;K_2O$ increased. The formation age of sericite has been determined to be Jurassic, which corresponds well to the intrusion age of the biotite granite nearby.

• Journal of the Mineralogical Society of Korea
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• v.25 no.4
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• pp.221-231
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• 2012

Uljin cassiterite deposit had been known to be a pegmatitic origin derived from the Wangpiri (Buncheon) granitic gneiss of Precambrian period. Lithium ore also shows the same origin and its lithium bearing mineral was ascertained to be a taeniolite. But the presence of leucocratic granites which played the role of host rocks haven't been clearly designated yet in these provinces. Even though Bonghwa and Youngweol sericite deposits situated in the vicinities of Hambaeg syncline had been known to have their host rocks as Hongjesa Granites of Precambrian period and Pegmatitic migmatite of unknown age respectively. But younger leucocratic granites are characterized by more amounts of albite and sericite (muscovite-3T type) than those of the older granitic rocks which contain plenty of biotite and chlorites. Although the younger granites show rather higher contents of alkalies such as $Na_2O$ (0.13~8.03 wt%) and $K_2O$ (1.71~6.38 wt%), but CaO (0.05~1.21 wt%) is very deficient due to the albitization and greisenization. Manisan granite, which is assumed to be Daebo granite which intruded the Gyunggi Gneiss Complex was again intruded by leucocratic granite whose microclinized part changed into kaolins. Taebaegsan region shows a wide distribution of carbonate rocks which are especially favorable to the ore depositions. And the presence of alkali granites which formed in the later magmatic evolution are well known to be worthwhile to the prospections of various rare metals and REEs resources.

• Economic and Environmental Geology
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• v.40 no.6
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• pp.761-769
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• 2007

We made 712 thermal property measurements on igneous, metamorphic and sedimentary rock samples from Gyeonggi-do, Gangwon-do and Chungchung-do, Korea. The average thermal conductivities of igneous, metamorphic and sedimentary rocks are 3.58W/m-K, 4.16W/m-K and 4.53W/m-K, respectively. Thermal conductivity of granite and gneiss are 2.13-5.87W/m-K and 2.26-6.67W/m-K, with average values of 3.57W/m-K and 3.945W/m-K, respectively. The average of thermal diffusivities are $1.43mm^2/sec\;and\;1.55mm^2/sec$, respectively; the average of specific heat values are 0.914J/gK, 0.912J/gK for granite and gneiss samples, respectively. The thermal conductivity of a rock type generally have a wide range because it depends on various factors such as dominant mineral phase, micro-structure, anisotropy, and so on.

• Economic and Environmental Geology
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• v.10 no.1
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• pp.1-18
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• 1977

Chongyang tungsten ore deposits, one of the most important tungsten mines in South Korea, me open space filling hydrothermal vein deposits embedded in Precambrian biotite gneiss and, Cretaceous (?) granite porphyry. Some wolframite-bearing quartz veins are closely associated with -quartz porphyries which strike about $N15^{\circ}-25^{\circ}W$ and dip $800^{\circ}SE$ to vertical. Mineralization took place in near vertical vein systems of 5 to 2000 meter long in the biotite gneiss and granite porphyry stock during early Cretaceous and Tertiary (?) period. The hydrothermal mineral paragensis has indicated that there were two major stages: vein and vug stages. The principal vein mineral is wolframite in a gangue of quartz with small amount of fluorite, pyrite, beryl and carbonate minerals. Present in minor amounts are molybdenite, bithmuthinite, native bismuth, arsenopyrite, galena, chalcopyrite, pyrrhotite, sphalerite and scheelite. Fluid inclusion study from the minerls at Chongyang mine reveals that vein stage fluids attained a temperature range of $200^{\circ}C-355^{\circ}C$ and vug stage $160^{\circ}C-350^{\circ}C$. The filling temperatures show the higher range of $200^{\circ}-355^{\circ}C$ in quartz and $280^{\circ}C-348^{\circ}C$ in beryls, whereas the lower emperature range of $283^{\circ}C-295^{\circ}C$ in rhodochrosite and $160^{\circ}-253^{\circ}C$ in fluorites. These temperatures are in reasonably good agreement with mineral paragnesis in this ore deposits. Volfamite minerals were analysed for major components. $WO_3$, MnO and FeO by wet chemical method. Chemical analysis indicates that they contain 70.56-71.54% $WO_3$, 8.52-10.01% MnO and 10.00-11.58% FeO. MnO/FeO ratios of wolframites shows the range of 0.78-0.94 which maybe indicates a comparatively high temperature type of hydrothermal deposits.

• Economic and Environmental Geology
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• v.30 no.2
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• pp.175-183
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• 1997

The concrete structure can be easily damaged due to alkali-aggregates reaction. There are several methods to identify alkali reactivity of aggregates. The most reliable method is mortar-bar test, but it takes 3 to 12 months for whole test. The authors applied "rapid method" which takes only 7 days for this test. The result of this rapid method follows; expansion ratio of mortar bar for natural aggregates taken at the Youngsan River ranges from 0.197 to 0.489%, but that from Changseong Lake has low expansion ratio of 0.147%, which is below the limit of allowance, 0.168%. Those from the Seomjin River range from 0.173 to 0.22%, and those from the Keum River range from 0.078% to 0.111%. In the case of higher expansion ratio than 0.168%, aggregates must be used with cement containing low alkali content or adding material consuming the alkali content of cement, for example, fly ash and silica fume, etc.. Most of natural aggregates in Cheolla area have no problem in physical properties, particularly the abrasion ratio is below 40%, the limit of allowance. The natural aggregate from Cheolla area consists mostly of gneiss, granite and volcanic rocks. The major alkali reactive materials are quartz mineral with undulatory extinction in gneiss and granite, and amorphous silica in volcanic rocks. Even if a certain aggregate consists of the same kind of rocks and has similar rock composition each other, content of alkali reactivity material can be various, because rock formation is locally different according to temperature and pressure. Therefore every rock type must be physically and chemically identified before using for aggregates.

• Geotechnical Engineering
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• v.14 no.5
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• pp.53-66
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• 1998

Since weathered soils are made by weathering process, the characteristics of weathered soils are strongly related to the originated rock and its forming process. Investigations on the originated rock and the weathering environments that decide the forming process are indispensable for the appropriate analysis on weathered soils. In this study, forming process of weathered soil is investigated by geological viewpoint. Test results show that weathering of rock is closely related to the distribution of rock-forming mineral and forming process. Weathered granite soils have the isotropic in-situ stress state and shearing behavior caused by the non-directional characteristics of originated rock. And weathered gneiss soils have the directional characteristics that mechanical behavior is determined by internal discontinuities. It it proved that the weathering resistance of Quarte is greater than that of feldspar and mica, and it is concluded that the thickness of weathered region is greatly influenced by the distribution of rock-forming mineral.