• Journal of the Mineralogical Society of Korea
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• 제24권3호
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• pp.165-178
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• 2011

The potential of petroleum generation was investigated by clay mineralogical changes of illite-smectite on the sedimentary basins: Tertiary Pohang basin and Cretaceouls Gyeongsang basin on land, and offshore basins east and west of Korea. Only disordered illite-smectite mixed layer minerals occur in the Pohang sediment, where petroleum generation cannot be expected due to low temperatures below $100^{\circ}C$. By contrast, the Gyeongsang basin is characterized by the occurrence of illite and high temperatures above $200^{\circ}C$ which are obtained by illite crystallinity. The high temperatures indicate that the Gyeongsang sediment ha, already passed through the oil generation stage. The change of disordered illite-smectite to R-l ordered illite-smectite is shown in the sediment of the East Sea continental shelf area at a depth of 2,500 m. Therefore, the oil generation can be expected in the sediments below the depth of 2,500 m. The sequential change of disordered illite-smectie to R=3 ordered illite-smectite through R=l ordered illite-smectite occurs in the sediments of West Sea continental shelf area with burial depth which shows the favorable condition for oil and gas generation. The temperatures of sediments measured by illite-smectite indicate that hydrocarbon potential is very low in the onland basins but high in the continental shelf areas.

• Ocean and Polar Research
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• 제26권2호
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• pp.245-253
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• 2004

The Intertropical Convergence Zone (ITCZ), where the southeast and northeast trade winds converge, is the effective climatological barrier that separates the southern and northern hemispheres in dust budget. Asian and N. American dusts dominate in fhe Pacific north of the ITCZ, while Central and S. American dust prevails south of the ITCZ. In order to understand the nature of latitudinal and depth-related variations of mineral composition in terms of relative position to the ITCZ, deep-sea core sediments were collected from $9^{\circ}N$ to $17^{\circ}N$ at a $2^{\circ}N$ interval along the $131.5^{\circ}W$ meridian and analyzed for mineral composition. The amount of illite in surface sediments decreases gradually from 65% at $17^{\circ}N\;to\;31^{\circ}N$ to 31% at 9f. In contrast, smectite increases from 11% to 56% southward. The observed mineralogical variation toward the ITCZ is attributed to the increased supply of volcaniclastic material transported via the southeast trade winds from the Central and South America source regions. Smectite-illite transition, a phenomenon that the amount of smectite increases over illite, occurs at around $10^{\circ}N$, the northern margin of the ITCZ. This result indicates that the change in latitudinal position of the ITCZ in geologic past could be recorded as a form of smectite-illite transition in deep-sea cores. The studied cores show down-core variation of mineral composition from illite-rich at the surface to smectite-rich clay suit at depths, similar to the latitudinal variation. The smectite-illite transitions observed in these cores are likely the records of changes in latitudinal position of the ITCZ. The depth and age of smectite-illite transition is getting shallower and younger toward equator, implying that the ITCZ was located farther north during late Tertiary and has shifted southward to the present position of $5^{\circ}N-10^{\circ}N$.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• 제5권2호
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• pp.145-154
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• 2007

In hydrothermal reaction tests, smectite-to-illite conversion was identified using a domestic bentonite which is favorably considered as a buffer material, and its dependency on various hydrothermal conditions was investigated. The analysis results of the XRD and Si concentration indicated that the smectite-to-illite conversion was a major process of bentonite alteration under the hydrothermal conditions. The temperature, potassium concentration in solution, and pH were observed to significantly affect the smectite-to illite conversion. A model of conversion reaction rate was suggested to evaluate the long-term stability of smectite composing a major constituent of bentonitic buffer. It was expected from the evaluation results that the smectite would keep its integrity for very long disposal time under a normal condition, whitens it might be converted to illite by 50 percent after over $5{\times}10^4$ year of disposal time under a conservative condition and consequently lose its swelling capacity as a buffer material of a repository.

• Korean Journal of Soil Science and Fertilizer
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• 제39권5호
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• pp.245-252
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• 2006

This experiment was conducted to investigate the distribution and compositions of clay mineral and to replenish the soil classification system in Korea. Soil layer samples were collected from 26 residuum and colluvium soil series out of 390 soil series in Korea, and then analyzed for soil physical and chemical characteristics, mineral and chemical compositions of clay in B horizon soils. Major clay minerals of residuum and colluvium were illite and chlorite in soils originated from the sedimentary rock such as limestone, shale, sandstone and conglomerate; quartz and kaolin in soils originated from rhyolite, neogene deposits, porphyry and tuff; and kaolin and quartz in the soils originated from granite, granite gneiss and anorthosite. Clay minerals in Korean soils were divided into 4 groups: mixed mineral group(MIX) mainly contained with illite, kaolin and vemiculite; kaolin group(KA) with kaolin and illite; chlorite group(CH) with chlorite and illite; and smectite group(SM) with kaolin, illite and smectite. The most predominant clay mineral group was kaolin group(KA) with kaolin and illite; an mixed mineral group(MIX) with illite, kaolin and vemiculite. Cation exchange capacity (CEC) of clay was low in the soils mainly composed with MIX and KA groups and silica-alumina molar ratio of clay was high in the soils composed with SM group

• Nuclear Engineering and Technology
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• 제55권4호
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• pp.1495-1506
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• 2023

For the safe disposal of high-level radioactive waste using Engineered Barrier Systems (EBS), bentonite buffer is used by its high swelling capability and low hydraulic conductivity. When the bentonite buffer is contacted to heated pore water containing ions by radioactive decay, chemical alterations of minerals such as illitization reaction occur. Illitization of bentonite indicates the alteration of expandable smectite into non-expandable illite, which threatens the stability and integrity of EBS. This study intends to provide a thorough review on the information underlying in the illitization of bentonite, by covering basic clay mineralogy, smectite expansion, mechanisms and observation of illitization, and illitization in EBS. Since understanding of smectite illitization is crucial for securing the safety and integrity of nuclear waste disposal systems using bentonite buffer, this thorough review study is expected to provide essential and concise information for the preventive EBS design.

• Economic and Environmental Geology
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• 제42권5호
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• pp.395-401
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• 2009

The smectite-illite (SI) reaction is a ubiquitous process in siliciclastic sedimentary environments. For the last 4 decades the importance of smectite to illite (S-I) reaction was described in research papers and reports, as the degree of the (S-I) reaction, termed "smectite illitization", is linked to the exploration of hydrocarbons, and geochemical/petrophysical indicators. The S-I transformation has been thought that the reaction, explained either by layer-by-layer mechanism in the solid state or dissolution/reprecipitation process, was entirely abiotic and to require burial, heat, and time to proceed, however few studies have taken into account the bacterial activity. Recent laboratory studies showed evidence suggesting that the structural ferric iron (Fe(III)) in clay minerals can be reduced by microbial activity and the role of microorganisms is to link organic matter oxidation to metal reduction, resulting in the S-I transformation. In abiotic systems, elevated temperatures are typically used in laboratory experiments to accelerate the smectite to illite reaction in order to compensate for a long geological time in nature. However, in biotic systems, bacteria may catalyze the reaction and elevated temperature or prolonged time may not be necessary. Despite the important role of microbe in S-I reaction, factors that control the reaction mechanism are not clearly addressed yet. This paper, therefore, overviews the current status of microbially mediated smectite-to-illite reaction studies and characterization techniques.

• Proceedings of the Korean Geotechical Society Conference
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.567-574
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• 2000

The purpose of this study is to examine mineralogical properties of the soft clay that is distributed widely in Samsan area, Ulsan. XRD analysis were examined to find the quantities of the clay minerals. And XRF, SEM and EDX analysis were also examined to investigate the chemical compositions and the structures of the clay. The properties of the samples from 2 sites in Samsan area were that the minerals of the clay were illite, kaolinite, chlorite, smectite and etc.. The plenty of illite has 38 to 53% of content in whole study area. And kaolinite had 18 to 30%, chlorite had 15 to 25%, and smectite had 4 to 12% of content, respectively. The results of SEM observation showed that appearances of Ulsan clay were sheet, plannar or needle form. Ulsan clay included the salt crystal of cubic and the foraminifera, which were related with the content of organ.

• Economic and Environmental Geology
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• 제28권4호
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• pp.327-335
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• 1995

Illite/smectite (I/S) in the Beaufort-Mackenzie Basin, Arctic Canada has been scrutinized on the basis of mineralogical analysis of 215 core and drill-cutting samples from 22 exploratory wells onshore and offshore. I/S in the Beaufort-Mackenzie Basin includes the following four types: random, a mixture of random and ordered, R1-ordered, and R>1-ordered I/S. A mixture of random and ordered I/S occurs in the transitional interval between random and R>1-ordered I/S, and may represent a metastable state in the ordering reaction. A widespread occurrence of the mixture in natural environments suggests that the ordering reaction may be a slow process that results in co-existence of reactants and products. K-saturation experiments show that layer charges of expandable layers in I/S are variable. High-charge expandable layers transform into illite-like layers upon simple K-saturation. K-saturation alters the composition and/or the degree of ordering in I/S, suggesting that illitization in nature can be transformational.

• Economic and Environmental Geology
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• 제34권3호
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• pp.243-254
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• 2001

Variation in relative contents of clay minerals was used to genetically interpret depositional environment of the Upper Jurassic Solnhofen limestone. Mineralogical examination of whole rocks and clay fractions indicates that the faule and flinz beds are composed mainly of calcite and quartz with minor amount of clay minerals such as illite, kaolinite, and smectite. Smectite shows a trend of illitization: illite layers increase with increasing of burial depth. With increasing burial depth, relative abundance of kaolinite with quartz and illite increases. This implies that the Solnhofen basin was formed during the transgression based on reduce of terrigenous influx.

• Economic and Environmental Geology
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• 제28권4호
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• pp.315-326
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• 1995

The layer charge characteristics of smectites from the Tertiary basins in the Pohang area have been studied in detail using the alkyl-ammonium method. On the basis of layer charges, the smectite in the Pobang area can be classed as normal and high-charge (hc) smectite. The layer charge of the normal smectite averages 0.3, and ranges from 0.25 to 0.38/half unit cell. The hc-smectite collapses on K-saturation to become illite-like material and shows $10{\AA}$-series reflections on X-ray diffraction. The layer charge of the he-smectite ranges from 0.5 to 1. The layer cbarges of the Pohang smectite are in general heterogeneous. The layer charges distribute between 0.21 and 0.45, and the most frequent layer charge is 0.30~0.32. The layer charge and the layer charge distribution do not appear to be related to stratification or basins of occurrence. Thus, the layer charge may not have developed as a result of burial. Rather, it may have developed due to heat and hydrothermal solutions associated with volcanic activities. Volcanic sills and dykes are ubiquitous in the region.