• Economic and Environmental Geology
• /
• v.30 no.2
• /
• pp.81-87
• /
• 1997

Chonnam and Kyongsang clay alteration areas are distributed in volcanic fields of the Yuchon Group in late Cretaceous period. The host rock of the Chonnam alteration area is generally acidic and that of the Kyongsang alteration area is acidic to dominantly intermediate volcanics. The important difference of two alteration areas is source of fluid; the Chonnam alteration area is characterized by dominantly meteoric water and the Kyongsang alteration area is characterized by dominantly magmatic water. Accordingly, the high temperature minerals such as pyrophyllite and andalusite, and boron bearing minerals such as dumortierite and tourmaline are common in the Kyongsang alteration area. In contrast to this, the lower temperature minerals such as kaolin and alunite are common in the Chonnam alteration area. The mineralogical difference of two alteration areas were depended on the difference of the formation temperature of clay deposits. The other important geochemical difference is the chemistry of hydrothermal solution such as pH. The alteration of "acid-sulfate type" with alteration mineral assemblage of alunite-kaolin-quartz is dominant in the Chonnam alteration area, which was caused by the attack of strong acid and acid solution. In contrast to this, the that of "quartz-sericite type" with the mineral assemblage of sericite-quartz is dominant in the Kyongsang alteration area, which was caused by the attack of neutral or weak acid solution. Also, the Kyongsang and Chonnam alteration areas show the difference in structural setting; the Chonnam alteration area is commonly associated with silicic domes and the Kyongsang alteration area is commonly associated with calderas.

• Economic and Environmental Geology
• /
• v.48 no.1
• /
• pp.41-49
• /
• 2015

Recently developed illite-age-analysis(IAA) approach was applied to determine the fault-reactivated events for the Inje fault that cut through Precambrian biotite granitic gneiss with NNE-SSW trend in the middle of Korean peninsula. Three distinct fault-reactivated events of shallow crustal regime were recognized using the combined approach of optimized illite-polytype quantification and K-Ar age-dating of clay fractions separated from 4 fault clay samples: $87.0{\pm}0.12Ma$, $65.5{\pm}0.05$ and $66.6{\pm}1.38Ma$, $45.6{\pm}0.15Ma$, respectively. As well, $2M_1$ illite ages of 193~196 Ma and $254.3{\pm}6.96Ma$ were discernible, which may be related to the fault-activated time in the relatively deep crust. The study results suggest that the Inje fault would be firstly formed at $254.3^{\circ}$ ${\ae}6.96Ma$ and sporadically reactivated in shallow regime since about 87 Ma. These reactivation events in shallow regime might be due to the Bulguksa orogeny that would be strongly influenced in Korean peninsula at that time.

• 한국해양학회지
• /
• v.24 no.1
• /
• pp.39-51
• /
• 1989

A total of 139 surface sediment samples, collected from the continental shelf and slope off the southeastern coast of Korea, were analyzed in order to understand their grain-size, mineral composition and organic carbon content. Based on the grain-size characteristics, five surface sedimentary facies were distinguished: sand, clay, mud, sand-mud mixed, and sand-clay mixed facies. The sand facies appears to be composed mostly of relict sand. For mud, most of which seem to be of recent origin, two different sources were suggested, based principally on their areal distribution pattern and the local hydrographic conditions. Heavy mineral composition of the fine-sand size fraction allowed us to distinguish different sand populations from the study area. On the whole, the Hupo Bank sediments showed a high content of garnet, while the sediments from the northern part of the continental shelf were characterized by a relatively high content of metamorphic minerals (kyanite, sillimanite, andalusite, staurolite). Among clay minerals, the most abundant was illite, with chlorite, kaolinite and smectite following in decreasing order. Organic carbon contents in the sediments of the study area were generally high and showed an average value of 1.94%. The sediment grain-size exerted a strong influence on the organic carbon content. The highest organic carbon content, on the other hand, was found in the continental slope sediments.

• Journal of Conservation Science
• /
• v.37 no.5
• /
• pp.545-556
• /
• 2021

In this study, we aimed to elucidate the materialistic characteristics of 11 pieces of earthenware belonging to the Neolithic and Bronze Age excavated from Jeongseon Auraji, South Korea. As a result, the chemical composition of earthenwares belonging to the early Bronze Age was distributed in the intermediate area between the Neolithic and Bronze Age earthenwares, but no significant difference was confirmed based on their manufacturing period. Upon comparison, the earthenwares excavated from Jeongseon Auraji site were found to comprise less acidic components than those excavated from Yeongdong, and are characterized by the alkaline components depending on the excavated site. In the rare earth elements distribution pattern, all the analyzed earthenwares exhibited similar pattern, confirming that the raw materials present in the clay were the same. As a result of microstructure analysis, the clay particles and voids were found to be irregularly distributed in the analyzed earthenwares. Neolithic earthenwares exhibited many irregular voids, and an arrangement of aluminosilicate, including feldspar, was observed along with the clay substrate. Furthermore, we confirmed that the empty space in early Bronze Age earthenwares was filled with fine particles and cube crystals. Moreover, the main mineral phase of earthenwares excavated from Jeongseon Auraji exhibited similar composition, and therefore, there was no significant difference in the firing temperature of these earthenwares. The firing temperature of the earthenwares ranged from 750 to 850℃.

• Economic and Environmental Geology
• /
• v.55 no.2
• /
• pp.197-207
• /
• 2022

This study investigated spectroscopic exploration of Myeonsan formation, the titanium(Ti) ore hostrock, in Joseon supergroup based on machine learning technique. The mineral composition, Ti concentration, spectral characteristics of Myeonsan and non-Myeonsan formation of Joseon supergroup were analyzed. The Myeonsan formation contains relatively larger quantity of opaque minerals along with quartz and clay minerals. The PXRF analysis revealed that the Ti concentration of Myeosan formation is at least 10 times larger than the other formations with bi-modal distribution. The bi-modal concentration is caused by high Ti concentrated sandy layer and relatively lower Ti concentrated muddy layer. The spectral characteristics of Myeonsan formation is manifested by Fe oxides at near infrared and clay minerals at shortwave infrared bands. The Ti exploration is expected to be more effective on detection of hostrock rather than Ti ore because ilmenite does not have characteristic spectral features. The random-forest machine learning classification detected the Myeonsan fomation at 85% accuracy with overall accuracy of 97%, where spectral features of iron oxides and clay minerals played an important role. It indicates that spectral analysis can detect the Ti host rock effectively, and can contribute for UAV based remote sensing for Ti exploration.

• Journal of the Korean Magnetics Society
• /
• v.12 no.1
• /
• pp.7-13
• /
• 2002

The studies of non-figure plain coarse pottery from Jeju island is very important because it can explain the characters of plain coarse potteries of the bronze age and the early iron age. In this study, We analyzed the non-figure plain coarse popery from Jeju island in two ways. One is analysis of the chemical composition using X-ray fluorescence spectrometer and X-ray diffraction, the other is analysts of clay mineral contained iron, oxidized iron's genus, valence state and magnetic properties using Mossbauer spectroscopy. We confidence that non-figure plain coarse pottery is chiefly made of silicate minerals, like SiO$_2$. The content of noncrystalline ferrihydrite is supposed to be below 5-10 wt%, non-figure plain coarse pottery is considered to partly consist of Jeju island clay, which is made of neutral volcanic rock and the valence state of iron is Fe$\^$2+/ and Fe$\^$3+/. We presume the reason that the magnetic hyperfine field is lower than that of pure goethite is the change of crystal structure which transforms the combination states of Fe ions while the clay is being fired.

• Journal of Soil and Groundwater Environment
• /
• v.15 no.5
• /
• pp.23-31
• /
• 2010

For an efficient remediation of Pb-contaminated soil (S-1) in a clay shooting range, a soil washing test was performed with mineral acid, organic acid, chelating agent, and chloride. The Pb extraction efficiency of extractant (0.1 M) used in the washing test showed the order of HCl > $Na_2$-EDTA > NTA > DTPA > citric acid > malic acid > succinic acid > acetic acid > $CaCl_2$ > $MgCl_2$, for S-1 soil. As compared to initial Pb concentration, extraction efficiency by the concentration of extractant was 93.35%, 80.80%, 73.92%, and 24.57% in S-1 soil for HCl (0.5 M, pH 1.10), $Na_2$-EDTA (0.01 M, pH 3.99), citric acid (0.5 M, pH 1.27), and $MgCl_2$ (0.1 M, pH 8.82), respectively. S-1 soil had 56.83% of residue form and 43.17% of non-residue form (18.04% of exchangeable form), respectively. Although the concentrations of these fractions sharply decreased after HCl washing, since the exchangeable forms with relatively large mobility are still distributed as high as 18.78% (to Pb total content in residual soils) in S-1 soil, it is necessary to devise a proper management plan for residual soils after soil washing application.

• Economic and Environmental Geology
• /
• v.39 no.6 s.181
• /
• pp.771-786
• /
• 2006

Imha lake has a high turbid water which keeps up during a few months, as comparing to other dams. Origins of the high turbid water derive from suspended materials which compose of micro particles of clay and rock-forming minerals. They are the weathered products from surface rocks that relate with particular geology in drainage field of the Imha dim. Accordingly we have fundamentally surveyed the kinds, properties, distribution and structures of general geology, found a few particular geology that source clay materials, and traced the passage that their weathered products enter the dam. We have suggested the basic origins of increase in turbid degree from detecting kinds and behavior of the suspended materials cause high turbid water in the Imha lake.

• Journal of Industrial Technology
• /
• v.26 no.B
• /
• pp.93-99
• /
• 2006

Centrifuge model experiments were performed to investigate the confining effects of the sheet piles, installed to the sides of soft clay ground treated with sand compaction piles, on the bearing capacity and concentration ratio of composite ground. For the given g-level in the centrifuge model tests, replacement ratio of SCP and the width of surcharge loads on the surface of ground with SCP, the confining effects of installing the sheet piles on the edges of SCP ground on the bearing capacity, change of stress concentration ratio and failure mechanism were investigated. Kaolin, one of typical clay mineral, and Jumunjin standard sand were used as a soft clay ground and sand compaction pile irrespectively. As results of experiments, lateral confining effect by inserting the model sheet piles fixed to the loading plate was observed. For the strip surcharge loading condition, the yielding stress intensity in the form of the strip surcharge loads tends to increase with increasing the embedded depth of sheet piles. The stress concentration ratio was found not to be influenced consistently with the embedded depth of sheet piles whereas the effect of stress intensity on stress concentration ratio shows the general trend that values of stress concentration ratio are relatively high at the initial stage of loading and tend to decrease and converge to the certain values. For the failure mechanism in the case of reinforced with sheet piles, displacement behavior related to the punching failure, settlement right beneath the loading plate occurred since the soil was confined with sheet piles, was observed.

• Journal of Conservation Science
• /
• v.25 no.2
• /
• pp.131-145
• /
• 2009

Goryeong Yangjeondong Petroglyph on the joint face of the bedrock (6m in width, 3m in height) composed of the green sandstone has circles and shield pattern sculptures. The rock is mainly composed of quartz, feldspar, chlorite, illite and calcite with the clay minerals. These clay minerals occur as pore lining, replacement of component and pore fillings. Investigated the weathering aspects including the connection between soluble salt and rock weathering and the stability of the bedrock with petroglyphs. The Major deterioration aspect are grain peel-off, surface exfoliation, cracks and damage. And the bedrock where the joints and cracks advance is interpreted with the fact that has the possibility of the falling rock. For conservation, adhesive need to cover crack and damage and consolidation is necessary in the surface which becomes weak.