• Journal of the Mineralogical Society of Korea
• /
• v.14 no.1
• /
• pp.39-51
• /
• 2001

공주군 유구면 일대의 화강암질 편마암의 풍화작용에 따른 원소의 거동과 pH와 이차광물과의 관계를 XRF, ICP-AES, ICP-MS를 이용한 원소분석결과를 통하여 검토하였다. 이 지역의 암석은 pH6 내외의 산성환경, 침철석, 아나타제와 같은 다양한 이차광물을 생성하면서 심각한 화학조성의 변화를 초래했다. 주원소의 화학조성을 이용한 풍화지수는 토양층에서 79~88로 모암 중의 사장석이 용해되고 흑운모가 변질되어 캐올리광물의 생성이 활발한 방향으로 풍화작용이 진행되었다. 지표층으로 가면서 Al에 대한 주 원소의 거동은 Si, Ca, Na, K, P가 감소하고 Fe, Ti, Mn이 증가하는 경향을 보이며 pH가 낮은 풍화단면에서 주 원소의 변화량이 더 크다. 이 풍화대에서 Mg은 거의 일정하다. Li, As 모든 전이원소는 pH가 감소함에 따라 증가하며 특히 이들 원소는 Fe의 함량과 비례해서 증가해 침철석과 공침하였거나 표면에 흡착되어 있는 것으로 보인다. Ga은 Fe와 비례하기는 하지만 변화량은 전 풍화단면에서 일정하다. Zr, Mo, Sn, Cd은 pH에 변화에 상관없이 일정한 반면에 Rb, Sr, Ba, Y, Pb, Th, U 등은 감소하는 경향을 보인다. 특히 Rb 과 Sr은 Ca에 비례해서 감소한다. 희토류원소는 전 풍화단면에서 감소하는 경향을 보이는데 $Al_2$$O_3$에 대한 상대적인 변화량을 보면 경희토류원소는 사프롤라이트(saprolite)하부와 상부에서 부화되어 있고 중부 사프롤라이트와 토양층에서 감소하는 반면에 중희토류원소는 사프롤라이트 하부와 상부에서 감소하고 중부사프롤라이트 및 토양층에서 부화되는 경향을 보인다. 전반적으로 희토류원소의 원자번호가 클수록 손실율이 커진다. 이 풍화단면에서 원소의 거동은 각 풍화층의 pH와 생성된 이차광물의 조성에 지배를 받았다.

• Journal of the Mineralogical Society of Korea
• /
• v.24 no.2
• /
• pp.133-143
• /
• 2011

In Mujoo area, the granitic pegmatites are developed in the granitic gneiss complex with Jurassic gneissic granites, where Nb-Ta mineralization were reported. Pegmatites are mainly composed of large crystals of quartz, feldspars of end-member orthoclase and albite, and muscovite. Nb-Ta minerals in study area are columbite (Nb > Ta) in composition. Chemistry of muscovites shows post-magmatic in origin and they are closely related with columbite. Large columbite, in pegmatites occurred with quartz and feldspars, while microcrystalline columbite is associated with muscovite. The Nb contents in large columbite are relatively higher than those in microcrystalline ones. Two pegmatites, 4~15 m in width and 120 m, 250 m in extension respective1y, are developed. Five drilling cores with total 600 m in length are finally obtained and revealed no possible potential for economic rare metals of Na-Ta deposits.

• The Journal of Engineering Geology
• /
• v.18 no.3
• /
• pp.311-319
• /
• 2008

Evaluation of an amplitude domain reflectometry (ADR) type soil moisture sensor as ThetaProbe ML2x using the response of frequency impedance was performed in a variety of soil porous media such as Jumunjin standard sand, weathered granite soil at Sangju area, and weathered gneiss soil at Jangsu area. The tested soils were classified with a dried condition and a wetted condition for comparing with soil volumetric water content under different installed depths of the measurement sensor. In the results the part of measurement rod including one signal rod and three shield rod 6cm in length was found to decrease the variation of measurement output voltage with insert 5cm over into the soil porous media. The measurement output voltage was verified to more stable output voltage under weathered granite soils and weathered gneiss soils contained the fine grain materials such as clay and silt minerals than the gradual grain material like as the standard sands. Therefore, measurement values by soil moisture sensor can be offered the more stable values when an contact volume between soil porous media and measurement sensor increase.

• The Journal of the Petrological Society of Korea
• /
• v.5 no.2
• /
• pp.135-141
• /
• 1996

La-Ce method is one of new geochronological methods developed recently. La and Ce are one of the rare earth elements, and, with Sm-Nd system. La-Ce system is very useful in understanding the evolution processes of crust and mantle. In this paper, I introduce the basic concept of the La-Ce method, and apply it in clarifying LREE pattern of source material of leuco-granitic gneisses from the Imweon area, Kangwon-do, and K-rich granite from the Anshan area in Liaoning Province, NE China. Sm-Nd data on the Anshan K-rich granites give an age of $3.16{\pm}0.06$ Ga($2{\sigma}$), with initial $^{143}Nd/^{144}Nd$=$0.50846{\pm}0.00005$ (${\epsilon}_{Nd}$=-1.5). On the basis of Ce and Nd isotopic ratio, leucogranitic gneiss and K-rich granite has been fractionated from the source material which had had similar to CHUR (chundritic uniform reservoir). And the initial ${\epsilon}_{Nd}$ value suggest that the crustal formation age of the Liaoning Province area, NE China was early Archean.

• Journal of Korean Society of Forest Science
• /
• v.22 no.1
• /
• pp.63-65
• /
• 1974

In this study, it is aimed to elucidate the relationship between the distribution of barren land in mountainous area and the geological and topographical characteristics of barren land in south Korea. To do this, the Land Use Classification Maps for mountainous areas (scale:1/50,000), compiled by the Roseources Survey Office of Mountainous and Forest Areas, Geological Maps of Korea (scale: 1/50,000), and Map of Geology of Korea (scale: 1,000,000), compiled by the construction Research Institute of Korea were used. The following conclusions have been obtained from this study. 1) Areas of strata that are most liable to dilapidation are found in such order of the broadest to broad as region of granite, granite-gneiss, and the specific stratum called the Kyongsang Stratum (named after the provinces) of the northern and southern Kyongsang Provinces comprising sandstones, gravelstones, crumblestones, and other stones similar to these species. These rocky hills occupy vast areas in size, so to speak, they are estimated to cover roughly 57% of the total barren and naked areas in the country. 2) The average size in area of barren and nated land, as one piece of land, 32 hectares of granite region, 15 hectares of granite-gneiss region and little less than 13 hectares of Kyongsang strata region were calculated.

• Economic and Environmental Geology
• /
• v.51 no.5
• /
• pp.409-428
• /
• 2018

Yeongdong area is located on the border zone between Precambrian Yeongnam massif and central southeastern Ogcheon metamorphic belt, in which Cretaceous Yeongdong sedimentary basin exists. Main geology in this area consists of Precambrian Sobaeksan gneiss complex, Mesozoic igneous and sedimentary rocks and Quaternary alluvial deposits. Above this, age-unknown Ogcheon Supergroup, Paleozoic sedimentary rocks and Tertiary granites also occur in small scale in the northwestern part. This study focuses on the link between the various geology and Rn concentrations in groundwater. For this, twenty wells in alluvial/weathered zone and sixty bedrock aquifer wells were used. Groundwater sampling campaigns were twice run at wet season in August 2015 and dry season in March 2016. Some wells placed in alluvial/weathered part of Precambrian metamorphic rocks and Jurassic granite terrains, as well as Cretaceous porphyry, showed elevated Rn concentrations in groundwater. However, detailed geology showed the distinct feature that these high-Rn groundwaters in metamorphic and granitic terrains are definitely related to proximity of aquifer rocks to Cretaceous porphyry in the study area. The deeper wells placed in bedrock aquifer showed that almost the whole groundwaters in biotite gneiss and schist of Sobaeksan gneiss complex and in Cretaceous sedimentary rocks of Yeongdong basin have low level of Rn concentrations. On the other hand, groundwaters occurring in rock types of granitic gneiss or granite gneiss among Sobaeksan gneiss complex have relatively high Rn concentrations. And also, groundwaters occurring in the border zone between Triassic Cheongsan granites and two-mica granites, and in Jurassic granites neighboring Cretaceous porphyry have relatively high Rn concentrations. Therefore, to get probable and meaningful results for the link between Rn concentrations in groundwater and surrounding geology, quite detailed geology including small-scaled dykes or vein zones should be considered. Furthermore, it is necessary to take account of the spatial proximity of well location to igneous rocks associated with some mineralization/hydrothermal alteration zone rather than in-situ geology itself.

• Journal of Korean Society of Forest Science
• /
• v.86 no.2
• /
• pp.186-199
• /
• 1997

The soils derived from granite gneiss occupy almost one third of the land area in Korea. The soils under forest vegetation, formed on granite gneiss, in Sun chon-shi, Chollanam-do in southern part of Korea, were studied to evaluate the weathering and the transformation of primary minerals into secondary minerals, clay minerals. The studied soils contained large amounts of ferromagnesian minerals, weathered biotites and were well weathered, strongly acid and low in organic matters and in ration exchange capacity. The clay contents in the Bt horizon were almost two times higher than those in the C horizon. The O horizon had a thin layer which consisted of a little decomposed plant components with a granic fabric and high porosity, and showed the micromorphological characteristics of moder humus. The related distribution pattern of the E horizon were enaulic and large amounts of silts and small amounts of sand grains were another characteristics of the E horizon. The most striking micromorphological features were multilaminated clay coating and infillings in the voids in the Bt and C horizons, and generally limpid ferriargillans ejected from the biotites and imparted red color to the soils in the Bt horizon. High clay contents in the Bt horizon was not only due to clay translocation, but also due to intensive in situ mineral weathering in this horizon. The most significant pedogenic process, revealed by the petrographic microscope and SEM, was the formation of iron oxides from biotites, the formation of tubular halloysites and the weathering models of biotites; wedge weathering and layer weathering. The thick coating on the weathering biotites showed the characteristics of the weathering process and the synthetic hematites were revealed in clays by TEM. Total chemical analysis of clays revealed extensive loss of Ca, and Na and the concentration of Fe and Al. Mineralogical studies of clays by XRD showed that micas were almost completely weathered to kaolinite, vermiculite-kaolinite intergrade, hematite, gibbsite, while halloysites from other primary minerals. Some dioctahedral mica appeared to be resistant in the soils. Parent rock of the soils contained a considerable amounts of biotites and this forest soils showed especially a dominant characteristics of biotite weathering.

• Korean Journal of Soil Science and Fertilizer
• /
• v.24 no.1
• /
• pp.1-9
• /
• 1991

A study was carried out to investigate the composition of rock-forming minerals and mineralogical characteristics of the five major parent rocks in Korea. The identification was done through the analyses of chemical. X-ray diffraction, thermal(DTA, TG), infrared spectroscopic, and microscopic methods. Among these methods, X-ray diffraction was considered to be the most rapid and effective way to identify minerals in the parent rocks. The main rock-forming minerals of the parent rocks were feldspars, quartz, and micas in granite and granite-gneiss, calcite and dolomite in limestone, quartz and calcite in shale, plagioclase and augite in basalt. A small amount of sesquioxides was identified as a accessory mineral by means of DTA from the parent rocks of Weoljeong series(granite) and Cheongsan series(granite-gneiss). The abrasion pH affecting the soil formation ranged from 7.5 to 8.4 in the parent rocks containing ferromagnesian minerals and carbonates. In the granite and granite-gneiss of which the main rock-forming minerals were feldspars and quartz with low content of biotite, the abrasion pH ranged from 6.2 to 6.4. In chemical composition of the parent rocks, Si, AI, and K oxides tented to increase with higher contents of quartz, feldspars, and muscovite, while Fe and Mg oxides with higher content of biotite, chlorite, amphiboles, and augite. Higher ignition loss in limestone and shale resulted in the release of $CO_2$ from calcite and/or dolomite.

• Economic and Environmental Geology
• /
• v.37 no.3
• /
• pp.355-364
• /
• 2004

A study on the weathering grade classification has been performed for granite and granite gneiss in Korea. The qualitative classification criteria of weathering were reviewed and then modified with field studies for the weathered rock masses. The thin section observations and XRD analyses for the different weathering grades rock samples showed the petrographical and petrophysical difference with respect to the weathering : the proportion of weathering-resistant minerals suck at quartz and orthoclase has a tendency to increase with the development of weathering, but that of weathering-sensible minerals such as anorthite and biotite is decreased. The ranges of physical and mechanical rock properties for different weathering grades were obtained from the laboratory rock tests and field tests for the studied rocks. And then, along with $RDI_{sq}$(Fookes et al., 1988), the weathering index $I_{a}$, (Woo, 2003) has been developed in this study to demarcate the weathering grade. Those two indices rely mainly on the water absorption ratio of rock and on the different rock strength. The range of these weathering indices have been determined with the physical and mechanical rock properties that can be obtained from simple field or laboratory tests in 4 grades $I_{a}$＞ 7 for F, 3.5 ＜ $I_{a}$ ＜ 10 for SW, 1.0 $I_{a}$＜ 6.0 for MW and $I_{a}$＜ 2.5 for HW. Consequently, the weathering index could be utilized to classify quantitatively the rock weathering grade, especially for the studied granites and the granite gneiss in Korea.

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