• Journal of Conservation Science
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• v.28 no.1
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• pp.39-52
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• 2012

The Usuki Stone Buddha Statues in Oita are consisted of 60 Buddhas which represent of Japan carved on the rock-cliff in the 12 to 14th centuries. The basement rock of the statues is dark gray welded lapilli tuff that containing the Aso-4 pyroclastic rock group. Deterioration maps for the Hoki I and the Furuzono Buddha Statues group show multi-directional fissures on the Cakra, and sheeting-off zone at the margin of uprising water. Deterioration rate of the Hoki I group was calculated fissure about 121 in number, 19% of sheeting-off zone and 51% of biological weathering in surface of area. And the Furuzono group was also evaluated as about 48 of fissures in number, 24% of sheeting-off zone and 41% biological weathering. The slope stability assessment results, the Hoki I developed discontinuous planes has possibility of planar, toppling and wedge failures in all caves. Ultrasonic velocity of the Aizen-myooh (basement rock) ranges from 1,520 to 2,794 (average 2,298m/s). And pedestal of Amita-yeorae which has been replaced by new fresh rock is measured as 3,242 to 4,141 (average 3,813m/s). Therefore, we establish of planing conservation treatment and reinforcement methods to fissure, cavity, sheeting-off zone in the Buddha surface.

• Journal of Conservation Science
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• v.25 no.2
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• pp.147-154
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• 2009

The change of strength and water vapour diffusion resistant by soluble salts was investigated in the tuff and granite used in many stone monuments of Gyeongju area. With $Na_2SO_4$ and $CaSO_4{\cdot}2H_2O$ were treated the rock samples to understand the difference of solubility. The densities of the tested rocks were increased by the impregnation of $CaSO_4{\cdot}2H_2O$ and $Na_2SO_4$. The flexural strength was increased in the tuff samples but decreased in the granite as the salts increased in the pore. In the tuff, the uniaxial compressive strength was increased by $CaSO_4{\cdot}2H_2O$, but decreased by $Na_2SO_4$. In the granite, it was decreased slightly by $CaSO_4{\cdot}2H_2O$, but increased by $Na_2SO_4$. The water vapour diffusion resistant was increased by the salts in both rocks. As results, it was cleared that the mechanical strength colud be increased in early stage of weathering by the accumulation of salt and water vapour diffusion resistant.

• Journal of Conservation Science
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• v.22
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• pp.121-134
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• 2008

The mechanism of stone exfoliation and its cause in relation to chemical weathering by soluble salt were studied. Chemical, mineralogical and physical analysis was performed in exfoliation samples from stone monuments. The representative salt is gypsum in the exfoliation samples. In order to understand the salt reaction, stone samples(tuff and granite) were treated with two type of the salt, gypsum and sodium sulfate, which have different solubility. The capillary water uptakes are slight increased in impregnated with Na2SO4 and weathering simulation of two rock types. It means that the rock is deteriorated in the near of the surface by $Na_2SO_4$. $CaSO_4{\cdot}2H_2O$ bring out the thicker exfoliation than $Na_2SO_4$ because it is penetrated into the deeper zone and amount of accumulated salt is more abundant in the inner part than in the near of the surface. The exfoliation was formed in the tuff by salt treatment and 30cycle of weathering simulation, but there are not significant symptoms of exfoliation in the granite by same condition. This result was caused by the different capillary water uptakes and porosity of the rocks. In the tuff, salt solutions are penetrated into the inner part due to its high capillary water uptakes and porosity but the granite, which has low value relatively, can be formed thinner exfoliation.

• Economic and Environmental Geology
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• v.50 no.3
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• pp.181-193
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• 2017

Mn-Fe phosphate mineral complexes included within the pegmatite are observed at Jurassic Cheolwon two-mica granite in Gyeonggi Massif, South Korea. The genetic evolution between the Cheolwon two-mica granite and pegmatite, and various trend of Mn-Fe phosphate minerals is made by later magmatic, hydrothermal, and weathering process based on mineralogical, geochemical analysis. The Cheolwon two-mica granite is identified as S-type granite, considering its chemical composition (metaluminous ~ peraluminous), post-collisional environment, low magnetic susceptibility, and existence of biotite and muscovite. The K-Ar age (ca. 153 Ma) of pegmatite is well coincident with age of the Cheolwon two-mica granite ($151{\pm}4Ma$). It indicates that these two rocks are originated from the same magma. Pegmatite indicates the LCT geochemical signature, and was classified as muscovite-rare element class / Li subclass / beryl type / beryl-columbite-phosphate subtype pegmatite. The triplite $\{(Fe^{2+}{_{0.4}},Mn_{1.6})(PO_4)(F_{0.9})\}$ is dominant phosphates in later magmatic stage which partly altered to leucophosphite $\{KFe^{3+}{_2}(PO_4)_2OH{\cdot}2H_2O\}$ and jahnsite $\{(Fe^{3+}{_{0.7}},Mn_{2.3})(PO_4)_2OH{\cdot}4H_2O\}$ by hydrothermal alteration. In particular, near fractures, the triplite has been separatelty replaced by the phosphosiderite ($Fe^{3+}PO_4{\cdot}2H_2O$) and Mn-oxide minerals during weathering stage.

• Economic and Environmental Geology
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• v.42 no.6
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• pp.527-539
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• 2009

The Kumho River flows through volcanic and sedimentary rocks at upstream and downstream regions and also through industrial district including dyeing complex before it meets the Nakdong River, and as a result, many factors can influence the geochemistry of river water. The concentrations of dissolved ions generally increased as it flows downstream. The concentrations of cations are in the order of Ca>Na>Mg>K, and those of anions are $HCO_3$>$SO_4$>Cl>$NO_3$. These results show that the weathering of sandstone and shale containing carbonate including calcite caused the enrichment of Ca and $HCO_3$. At first 4 sampling sites, Si contents are relatively high mainly due to the weathering of silicate minerals of volcanic rocks. However, Na and $SO_4$ contents are higher at downstream sites due to the industrial and municipal sewage. Piper diagram also shows that the geochemical patterns changed from Ca-$HCO_3$ to Ca-Cl/Ca-$SO_4$ and Na-Cl/Na-$SO_4$ type. When comparing the samples collected in May and July, the concentrations of dissolved ions in July are generally lower than those in May, which indicates that dilution by precipitation played an important role. In July the relative concentration of Ca increased, indicating that Ca in soils probably from fertilizer were mixed into the river water by precipitation. The river waters are mainly from precipitation. The dissolved ions are mainly from weathering of carbonate minerals and pollutants from municipal sewage and discharged water from industrial complex. The composition of oxygen and deutrium isotope in July showed higher values, which is contrary to the amount effect, maybe due to Youngchon Dam. The nitrogen isotope showed lower values in July than those in May, which can be interpreted to indicate mixing of nitrate from soils and fertilizer in the cultivated land by the heavy rain. The isotope composition of nitrate increased downstream, indicating that the influence of sewage and animal manure also increased downstream.

• Journal of the Korean Geographical Society
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• v.46 no.2
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• pp.134-151
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• 2011

The types of gnamma at the summit area of Mt. Geum, Sangju-ri, Namhae-gun, Gyeongsangnam-do are classified and geomorphic developments are investigated. The rocks facing the coast show high distributional density of gnamma due to the salt supply from the coast. The water content rate of gnamma distributed in flat rocks at the summit is highest in the bottom area and lowest in the outside area. Moreover, the quartz grains are fallen due to the weathering of feldspar in the crystalline rocks such as granites and the gnamma are merged and expanded as they develop. The average weathering rate of gnamma is 0.04mm/y and it slowed with time. The results on rate indicate that the gnamma are formed and developed at the present rather than the fossil landform or by subsurface weathering.

• Economic and Environmental Geology
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• v.36 no.6
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• pp.415-429
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• 2003

This study was objected to identify the difference of water quality and the characteristics of water contamination in adjacent bed-rock areas of Upper Hwajeonni and Guryongsan Formations in Miwon, Choongchungbuk-do, Korea. Water samples showed mainly (Ca, Mg)-$HCO_3$ type in Upper Hawjeonni Formation and (Ca, Mg)-$SO_4$ and (Ca, Mg)-$HCO_3$ types in Guryongsan Formation indicating the enrichment of $SO_4$ in major compositions. Groundwater quality could be divided into two groups based on the major weathering processes, implied by the ratio of bicarbonate to silica. Carbonate-silicate weathering predominates in Upper Hwajeonni Formation, and silicate weathering in Guryongsan Formation. Stream-water quality also appeared to be controlled by water-rock interaction. Cluster analysis identified three groups of groundwater and four groups of stream-water with distinctive geochemical characteristics. The results of factor analysis indicated that the levels of each chemical constituent in water samples derived from both natural weathering reactions and anthropogenic contamination sources. To delineate the pollution potential of water resources, Modified Pollution Index(M.P.I.) was developed. M.P.I. scores of water samples ranged from -0.08 to 0.18, with mostly positive along the rock quarry in Guryongsan Formation areas. M.P.I. scores appeared to be a useful predictor of metal contamination of water resources.

• Journal of Conservation Science
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• v.28 no.4
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• pp.329-341
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• 2012

Magai Wareiishi Jizo (Buddhist statue carved on rock surface) is close to shoreline and a part of rock block is periodically immersed by seawater. Rock material of the Wareiishi-jizo statue is composed mainly of medium or coarse-grained biotite granite and very durable. However, physical properties of the rock have been changed according to the complex interactions of the salt solution and surrounding environment. Exfoliation of the rock surface is a serious condition by salt crystallization. Exfoliation (14.6%) is concentrated on the upper part of the rock block with mainly boundary of seawater as the center. On the other hand, lower part of the rock block show black layers by contaminants deposition. In addition, brown discoloration and biological contaminants is overlapped. Rock surface show high discoloration rate of 50.5% (black discoloration, 29.2% > yellow discoloration, 14.1% > brown discoloration, 4.4% > green discoloration, 2.9%). Upper part of the rock block had a lot of change in the physical properties than lower part that is immersed by seawater. In particular, surface properties of the rock block was very weak state at the boundary surface of seawater permeation.

• Journal of the Mineralogical Society of Korea
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• v.20 no.4
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• pp.255-260
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• 2007

The loess on the Chinese loess plateau is not only the accumulation of Asian dust but also the source materials of Hwangsa. The eolian carbonates of the loess were dissolved and reprecipitated to form secondary pedogenic carbonates by the post-depositional weathering during the interglacial time. Mineralogical analysis shows that the secondary calcites are composed mostly of a nanosized fibrous calcite with rather constant width ($30{\sim}50nm$) and highly variable length. The nano calcite is the major authigenic mineral, which occurs as the fine-grained matrix of the loess and paleosol. The nano calcite was recently reported in the Hwangsa, where it was originated from the source regions of Chinese loess plateau.

• The Journal of the Petrological Society of Korea
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• v.21 no.4
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• pp.405-413
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• 2012

This study demonstrates the consolidation effect of ethylsilicate consolidants considering material characteristics and weathering degree of Samneunggyeseongakyukjonbul(rock-carved Yukjonbul Buddha in Samneung Valley) in Namsan, Gyeongju. The buddha statue is composed of alkali feldspar granite and contains numerous sets of joint with exfoliation and granular disintegration, therefore the statue is necessary to be treated for surface strength. The laboratory and in-situ tests of consolidation effect showed more increase of ultrasonic velocity that KSE 300, a relatively highly concentrated consolidant, performed more increase of ultrasonic velocity and decrease of porosity than others after treatments in weathered granite. And the consolidated rock with OH 100 was more resistant to salt weathering. For the buddha statues, KSE 300 is more applicable to enhance surface strength because it showed higher consolidation effect for long term than OH 100 and the statues has not been weathered by salts.