• Journal of the Mineralogical Society of Korea
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• v.18 no.3 s.45
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• pp.205-214
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• 2005

Some Quaternary faults developed in the eastern block of the Ulsan fault are Gaegok 1, Gaegok 2, Singye, Madong, Wonwonsa and Jinhyeon faults, which are characterized by thin gouge and narrow cataclasitic tones. This study was performed to emphasize the role of mineral alteration and microtexture in response to hydrothermal alteration of fault gouges during fault activity, using XRD, EPMA, BSE (backscattered electron image), and K-Ar age dating methods. Alteration minerals in fault gouges were formed in the age range of $44.3\~28.9Ma$ by hydrothermal alteration attributed to fault activity. XRD results show that fault gouges consist predominantly of clay minerals, quartz and feldspars. Clay minerals formed in the gouge zones are mainly composed of smectite with trace chlorite, illite and kaolinite. The evidence to support the hydrothermal alteration of preexisting minerals due to fault activity are easily recognized at the host rocks in contact with gouges zones. Injected gouge and calcite veins indicate that they were originated from multiple deformation by repeated fault activity. Gouge with green or greenish grey color, for example Jinhyeon fault, contains higher $Al_2O_3$ and lower MgO and CaO compared to those with reddish color. Various colors of fault gouge are intimately related to the chemical compositions of main constituent mineral as well as mineral assemblage.

• Journal of the Mineralogical Society of Korea
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• v.6 no.1
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• pp.27-37
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• 1993

The clay minerals such as sericite, pyrophyllite, chlorite and smectite abundantly occur in the Bobae pottery stone mine in Pusan. In this study, the processes which are responsible for the formation of these minerals were studied by examing their occurrence and mineralogical properties. The so-called pottery stone of this mine is characterized by the predominance of sericite and quartz. The sericite of the pottery stone is mostly $2M-{1}$ type. And many of quartz particles are smaller than a few micron in diameter. The pottery stone also contained a small amount of pyrophyllite and muscovite. The pottery stone deposit occurs within the Cretaceous rhyodacite and is particularly well developed near the contact with the quartz porphyry which intrudes the rhyodacite. The fact implies that the pottery stone is the product of hydrothermal alteration of the rhyodacite by the intrusion of quartz porphyry. The pottery stone was formed by the alteration that accompanies the dissociation of feldspar and chlorite in parent rocks and subsequent formation of sericte and quartz. Smectite, laumontite and kaolinite occur locally within the altered rocks. These minerals were formed after formation of pottery stone. It is noteworthy that beidellite occurs as a pink-colored clay from the altered rocks in the mine.

• Journal of the Mineralogical Society of Korea
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• v.30 no.1
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• pp.21-29
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• 2017

Surface soils on Barton Peninsula, King George Island, West Antarctica were investigated to acquire the mineralogical and geochemical data of soil in Antarctica. Multiline of techniques for example, X-ray diffraction (XRD), transmission electron microscopy (TEM)-electron energy loss spectroscopy (EELS), and wet chemistry analysis were performed to measure the composition of clay minerals, Fe-oxidation states, cation exchange capacity, and total cation concentration. Various minerals in sediments such as smectite, illite, chlorite, kaolinite, quartz and plagioclase were identified by XRD. Fe-oxidation states of bulk soils showed 20-40% of Fe(II) which would be ascribed to the reduction of Fe in clays as well as Fe-bearing minerals. Moreover, redox states of Fe in smectite structure was a ~57% of Fe(III) consistent to the values for the bulk soils. The cation exchange capacity of bulk soils ranged from 100 to 300 meq/kg and differences were not significantly measured for the sampling locations. Total cations (Mg, K, Na, Al, Fe) of bulk soils varies, contrast to the heavy metals (Co, Ni, Cu, Zn, Mn). These results suggested that composition of bed rocks influenced the distribution of elements in soil environments and soils containing clay compositions may went through the bio/geochemical alteration.

• The Korean Journal of Quaternary Research
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• v.23 no.1
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• pp.25-37
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• 2009

Geochemical composition and clay minerals of surface and core sediments around off the Jeju Island were analyzed for identification of sediment origins. The clay mineral distribution is mainly controlled by the sediment source and the dominant circulation pattern. Smectite is highly concentrated (>8%) in the northwest near the South Yellow Sea and in the outer-shelf mud patch. It seems to be due to the high supply of smectite transported from China where fine-grained sediments are discharged from modern and ancient Huanghe River. The relatively high abundance of kaolinite are found in northeastern nearshore area and the southwest near Changjiang estuary. It seems to be supplied from Changjiang River and the southwestern Korea rivers. The sediment accumulation rates measured by $^{210}Pb$ geochronrom mowere 0.20 to 0.54cm/mr or 0.15 to $0.42g/cm^2{\cdot}mr^{-1}$ AOJI, with decreasing rates from the west part to the east part, resulting in the supply of fine-grained suspended sediments from the Changjiang and Huanghe Rivers system. The discrimination diagrams clearly show that the sediments around Jeju Island in the northern East China Sea are ultimately sourced from Chinese rivers, especially from the Huanghe River, whereas the sediment in the northeast part might come from Korean rivers and the Jeju Island.

• Journal of the Mineralogical Society of Korea
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• v.5 no.2
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• pp.79-92
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• 1992

The Sarisan clay deposits of hydrothermal origin are found in the intensely weathered wto-mica granite in Yeoju area. The major clay minerals of the Sarisan mine are illite and montmorillonite with minor disordered kaolinite, vermiculite, and some interstratified mineral. Clay minerals were studied using various methods including X-ray diffraction, infrared absorption spectroscopy, electron microscopy, and thermal and chemical analyses. Illites occur as discrete illite or highly illitic interstratified mineral. They are of 1M and $2M_1$ polytypes and characterized by a low lattice charge (1.768-0.926 per unit formula), low $K^+$ content (0.741-0.902 per unit formula), and high Si/Al ratio (1.154-1.293) as compared with muscovite. Montmorillonites are highly negative charged and occasionally random-interstratified as I/S with 80-98% smectite. Hydrothermal alteration is more important than later weathering alteration for the formation of illite and montmorillonite clay minerals. The hydrothermal alteration took place through two stages; the formation of illite in the early stage and the formation of montmorillonite in the late stage. Disordered kaolinite and vermiculite are the weathering products of plagioclase and biotite, respectively.

• The Journal of the Petrological Society of Korea
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• v.25 no.4
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• pp.335-348
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• 2016

The fluvial Tamna Formation, consisting of conglomerate, sandstone and mudstone layers, is widely distributed in Jeiu Island. Various sizes of quartz crystals were identified from most of the Tamna Formation, including the mudstone layer. XRD analysis also shows that the mudstone layer is composed of various minerals, quartz, plagioclase, K-feldspar, mica, magnetite, hematite, olivine, amphibole, gibbsite, calcite, analcime and clay minerals such as illite, kaolinite, vermiculite, smectite, chlorite, $10{\AA}$-halloysite. There is a tendency showing that the more amount of kaolinite, vermiculite, and chlorite is present where the more amount of quartz crystals is present. It is likely that the main source materials contributing to the Tamna Formation were from the parental rocks containing abundant quartz grains, suggesting that the Tamna Formation could not be related to Jeju volcanic rocks, but possibly to pre-existing basement rocks. Thus, we propose that the Tamna Formation was formed from the materials derived from both pre-existing basement rocks and Jeju volcanic rocks, which were subsequently affected by diagenesis, hydrothermal alteration and weathering process.

• Journal of the Mineralogical Society of Korea
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• v.13 no.3
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• pp.121-137
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• 2000

Weathering profiles which were developed under a temperate, humid environment and relatively steep geography, show a thick saprolite and soil horiaon in the Precambrian granitic gneiss of the Yoogoo area. In the weathering profiles, secondary minerals such as interstratified biotite/vermiculite, tri- or di-octahedral vermiculite, halloysite, kaolinite, illite, smectite, gibsite and geothite were observed. Kaolinization of biotite is the most prevalent mechanism but vermiculitization is a minor from all ofweathering profiles. Biotite altered to B/V mixed layer-vermiculite, to illite and to halloysite, kaolinite and gibbsite. Halloysite is the most frequently observed weathering product of biotite in these profiles. Goethite is observed at the around or opened fissures of altered biotite. Tubular halloysite aggregates was fDrmed from dissolution-precipitation of plagioclase. The occurrence of halloysite aggregates is divided into a preferentially oriented type and a wrinkled one which were resulted from the dissolved type of plagioclase. Fe-bearing minerals have also been subjected to dissolution leaving the precipitation of geothite along dissolution voids. The profile of granitic gneiss is a typical weathering pattern showing a clay minerals increase toward the surface. Weathering of minerals were controlled by locally acidic and good-drainage environment, and formed a various and complicated secondary minerals in this study area.

• Economic and Environmental Geology
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• v.32 no.6
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• pp.611-631
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• 1999

Enviromental geochemisty and heary metal contamination at the Kongjueil mine creek were underaken on the basis of physicohemical properties and mineralogy for various kinds of water (surface, mine and ground water),soil, precipitate and sediment collected of April and December in 1998. Hydrgeochemical composition of the water samples are characterized by relatively significant enricant of Ca+Na, alkiali ions $NO_3$ and Cl inground and surfore water, wheras the mine waters are relatively eneripheral water of the mining creek have the characteristics of the (Ca+Mg)-$(HCO_3+SO_4)$type. The pH of the mine water is high acidity (3.24)and high EC (613$\mu$S/cm)compared with those of surface and ground water. The range of $\delta$D and $\delta^{18}O$ values (relative to SMOW) in the waters are shpwn in -50.2 to -61.6% and -7.0 to -8.6$\textperthousand$(d value=5.8 to 8.7). Using computer program, saturation index of albite, calcite, dolomite in mine water are nearly saturated. The gibbiste, kaolinite and smectite are superaturated in the surface and ground water, respectively. Calculated water-mineral reaction and stabilities suggest that weathing of silicate minerals may be stable kaolinite owing to the continuous water-rock reaction. Geochemical modeling showed that mostly toxic heavy metals may exist larfely in the from of metal-sulfate $(MSO_4\;^2)$and free metal $(M^{2+})$ in nmine water. These metals in the ground and surface water could be formed of $CO_3$ and OH complex ions. The average enrichment indices of water samples are 2.72 of the groundwater, 2.26 of the surface water and 14.15 of the acid mine water, normalizing by surface water composition at the non-mining creek, repectively. Characteristics of some major, minor and rate earth elements (Al/Na, K/Na, V/Ni, Cr/V, Ni/Co, La/Ce, Th/Yb, $La_N/Yb_N$, Co/Th, La/Sc and Sc/Th) in soil and sediment are revealed a narrow range and homogeneous compositions may be explained by acidic to intermediate igneous rocks. And these suggested that sediment source of host granitic gneiss colud be due to rocks of high grade metamorphism originated by sedimentary rocks. Maximum concentrations of environmentally toxic elements in sediment and soil are Fe=53.80 wt.% As=660, Cd=4, Cr=175, Cu=158, Mn=1010, Pb=2933, Sb=4 and Zn=3740 ppm, and extremely high concentrations are found are found in the subsurface soil near the ore dump and precipitates. Normalizing by composition of host granitic gneiss, the average enerichment indices are 3.72 of the sediments, 3.48 of the soils, 10.40 of the precipitates of acid mine drainage and 6.25 of the soils near the main adit. The level of enerichment was very severe in mining drainage sediments, while it was not so great in the soils. mineral composition of soil and sediment near the mining area were partly variable being composed of quartz, mica, feldspar, chlorite, vermiculite, bethierin and clay minerals. reddish variable being composed of quartz, mica, feldspar, chlorite, vermiculite, bethierin and clay minerals. Reddish brown precipitation mineral in the acid mine drainage identifies by schwertmanite. From the separated mineralgy, soil and sediment are composed of some pyrite, arsenopyite, chalcopyrite, sphalerite, galena, malachite, goethite and various kinds of hydroxied minerals.

• Journal of the Korean Geographical Society
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• v.28 no.1
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• pp.1-15
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• 1993

This research aims to investigate some respects of chemical weathering processes, espcially the amount of solute leaching, formation of clay minerals, and the chemical weathering rate of granite rocks under present climatic conditions. For this purpose, I investigated geochemical mass balance in a small catchment and the mineralogical composition of weathered bedrocks including clay mineral assemblages at four res-pective sites along one slope. The geochemical mass blance for major elements of rock forming minerals was calculated from precipitation and streamwater data which are measured every week for one year. The study area is a climatically and litholo-gically homogeneous small catchment($3.62Km^2$)in Anyang-shi, Kyounggi-do, Korea. The be-drock of this area id Anyang Granite which is composed of coarse-giained, pink-colored miner-als. Main rock forming minerals are quartz, K-Feldspar, albite, and muscovite. One of the chracteristics of this granite rock is that its amount of Ca and Mg is much lower than other granite rock. The leaching pattern in the weathering profiles is in close reltion to the geochemical mass balance. Therefore the removal or accumulation of dissolved materials shows weathering patterns of granite in the Korean peninsula. Oversupplied ions into the drainage basin were $H^+$, $K^+$, Fe, and Mn, whereas $Na^2+$, $Mg^2+$, $Ca^2+$, Si, Al and $HCO-3^{-}$ were removed from the basin by the stream. The consumption of hydrogen ion in the catchment implies the hydrolysis of minerals. The surplus of $K^+$ reflects that vegetation is in the aggravation stage, and the nutrient cycle of the forest in study area did not reach a stable state. And it can be also presumed that the accumulation of $K^+$ in the top soil is related to the surplus of $K^+$. Oversupplied Fe and Mn were presumed to accumulate in soil by forming metallic oxide and hydroxide. In the opposite, the removal of $Na^+$, Si, Al resulted from the chemical weathering of albite and biotite, and the amount of removal of $Na^+$, Si, Al reflected the weathering rate of the bedrock. But $Ca^2+$ and $Mg^2+$ in stream water were contaminated by the scattered calcareous structures over the surface. Kaolinite is a stable clay mineral under the present environment by the thermodynamical analysis of the hydrogeochemical data and Tardy's Re value. But this result was quite different from the real assemblage of clay miner-als in soil and weathered bedrock. This differ-ence can be explained by the microenvironment in the weathering profile and the seasonal variation of climatic factors. There are different clay forming environments in the stydy area and these differences originate from the seasonal variation of climate, especially the flushing rate in the weathering profile. As it can be known from the results of the analysis of thermodynamic stability and characteristics of geochemical mas balance, the climate during winter and fall, when it is characterized by the low flushing rate and high solute influx, shows the environmental characteristics to from 2:1 clay minerals, such as illite, smectite, vermiculite and mixed layer clay minerals which are formed by neoformation or transformation from the primary or secondary minerals. During the summer and spring periods, kaoli-nite is a stable forming mineral. However it should consider that the other clay minerals can transformed into kaolinite or other clay minerals, because these periods have a high flushing rte and temperature. Materials which are directly regulated by chemical weathering in the weathered bedrock are $Na^+$, Si, and Al. The leaching of Al is, however, highly restricted and used to form a clay mineral, and that of Si falls under the same category. $Na^+$ is not taked up by growing veget ation, and fixed in the weathering profile by forming secondary minerals. Therefore the budget of $Na^+$ is a good indicator for the chemical weathering rate in the study area. The amount of chemical weathering of granite rocks was about 31.31g/$m^2+$/year based on $Na^+$ estimation.

• Journal of the Mineralogical Society of Korea
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• v.16 no.2
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• pp.151-159
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• 2003

$^{31}$ /P NMR and XRD have been used to study the mineralogical compositions and the phosphorus species in marine sediments near Wolsung nuclear power plant. The core samples with 30cm depth were investigated and no mineralogical changes have been found. The studied marine sediments were composed of quartz, albite, microcline, calcite, and some clay minerals such as illite, smectite, chlorite, and kaolinite. Only orthophosphate-monoester and very small amount of ortho-phosphate-diester were identified as phosphorus species in the studied sample, different from the species reported in other countries. These phosphorus species are mainly from organisms and was exposed to the oxic conditions. The consistent mineralogical compositions as well as the same phosphorus species throughout the entire core samples indicate that the constant oxic condition was kept without any changes in sedimentary conditions or the sediments were deposited with different sedimentary conditions, but later they were disturbed by other activities and exposed to the surface oxic conditions continuously.