• 한국지구과학회:학술대회논문집
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• 2010.04a
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• pp.52-52
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• 2010

동해 한국대지 남부(south Korea Plateau)에서 2010년 2월에 한국해양연구원의 온누리호를 이용하여 해저지형 및 자생광물 탐사가 실시되었다. 다중빔 음향측심기를 이용한 해저지형 조사는 2-3 km 탐사측선 간격으로 약 400 L-km 정도가 실시되었다. 조사구역 A($37^{\circ}$ 16'-18'N, $130^{\circ}$ 02'-16'E)는 890-1,900 m의 수심범위와 남쪽으로 갈수록 수심이 깊어져 울릉분지(Ulleung Basin)와 연결된다. 크고 작은 소규모의 구릉이 사면을 따라 다수 분포하고 있다. 조사구역 B($37^{\circ}$ 26'-40'N, $130^{\circ}$ 23'-34'E)의 정상부는 900-1,000 m로 비교적 평평하게 나타났고, 남동방향으로는 2,200 m까지 급격하게 수심이 증가하는 사면으로 이루어져 있다. 한국대지내 노출 암반지역은 남동쪽 사면의 일부 지역에 분포하고 있다. 자생광물 탐사는 일차적으로 천부지층 탄성파탐사를 수행하여 시료채취 가능 여부를 현장에서 확인한 후에, A 및 B구역내 11개 지점에서 드렛지를 이용하여 암석시료를 채취하였다. 채취된 암석은 주로 현무암이며, 많은 양의 화산기원 부석(pumice) 및 화산재(box core 자료)도 확인되었다. 또한, 인광석으로 추정되는 암석과, 망간단괴(manganese nodules)와 망간각(manganese crust)의 일부 시료도 채취하는데 성과가 있었다.

• Journal of the Mineralogical Society of Korea
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• v.8 no.1
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• pp.23-28
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• 1995

그레자이트가 한국에서는 최초로 남동 황해 대륙붕의 준표층 니질퇴적물에서 발견되었다. 이 지역의 수심은 70~80m이며, 표층 퇴적물은 수십cm 두께의 사질과 니질퇴적물이 교호하는 것으로 보아 조류의 영향을 받은 홀로세의 해침에 의하여 형성된 것으로 보인다. 그레자이트 입자는 0.1~2mm의 크기에 구상의 형태로 산출되며 니질퇴적물 내에 산점상으로 산포되어 있거나 0.5cm 정도의 엽리를 형성하고 있다. 이 광물은 강한 자성을 가지고 있으며 육안으로는 검은색을 띄나, 반사현미경하에서는 황백색을 띠며 등방성을 보인다. 그레자이트의 화학조성은 Fe=54.36, S=42.37, As=0.14, Si=2.25 wt.%로서 S=4일 때의 화학식은 Fe2.95S4이다. X-선 회절분석에 의한 단위포의 크기는=9.8635$\AA$, V=959.6$\AA$3이며 밀도는 4.094 gm/cc이다. 이 광물은 산출상태, 조직적 특징 및 수반광물의 종류로 보아 생물의 활동에 의한 환원조건의 니질퇴적물 내에서 자생한 것으로 추정된다.

• 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.

• 한국해양학회지
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• v.29 no.1
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• pp.17-27
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• 1994

The sediment collected from KODOS91-1 were studied using X-ray diffraction(SRD) analysis to clarify the composition and vertical distribution of clay minerals. Micropaleontological data(Radiolarians) was applied to identify the changes in post-depositional environment and chemical mechanism leading to the formation of authigenic minerals. The result show that the highest concentration of smectite is occurred in the lower part(Unit II, III) of sediment column and the lowest concentration in the upper part(Unit I) whereas terrestrial minerals, such as illite, kaolinite and quartz, indicate the opposite trends. Radiolarians in the upper part are composed entirely of Quaternary/Tertiary mixtures, whereas in lower sediment units generally revealed the middle Miocene to the Eocene. This may imply that the Quaternary and Tertiary sedimentary processes were continuously affected by reworking of older sediments and subsequent resegmentation. The changes of the sediment color, peak pattern of minerals and presence of reworked microfossils at the unit boundaries have been interpreted as evidence of authigenic formation. Mineralogical characteristics of the sediments in study area strongly indicates changes in paleoenvironments through geologic time, including changes in post-depositional conditions by physical processes and chemical mechanisms.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.680-687
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• 1999

To understand the role of shelf sediment in phosphorus biogeochemical cycle, we carried out sequential sediment extraction (SEDEX) of P and porewater analysis on 14 core samples collected in the South Sea of Korea, SEDEX classified P-pools into 5 phases and results are grouped into two categories: reactive P (loosely sorbed-P and Fe bound-P) and refractory P (detrital inorganic-p, authigenic mineral-P and organic-P). Total P concentrations are decreased with sediment depth in all samples as a result of dissolution to porewater. Reactive P comprises about $20\~50\%$ of total P, and iron bound-P is the major form consisting $70\~80\%$ of reactive P-pool. Iron bound-P decreases sharply with depth. Depth profiles of dissolved P concentration in porewater show mirror image of iron bound-P, revealing the role of FeOOH as a regulator of reactive P supply to overlying water column. Authigenic mineral-P consists less than $5\%$ of total P, thus removal of reactive P by converting into refractory P seems inefficient in shelf sediment. This implies that continental shelf sediment sequesters P temporarily rather than permanently. Results show local variation. Nakdong estuary receiving large amount of terrigenous input shows the highest concentration of total P and reactive P. Here iron oxyhydroxides at the surface sediment control the water column flux of P from sediment. Although total P content at the surface is comparable (500$\~$600 ${\mu}g{\cdot}g^{-1}$) between the South Sea and East China Sea, the former contains more iron bound-P and less derital inorganic-P than the latter. Reasons for the difference seem due in part to particle texture, and to biological productivity which depends roughly on the distance from land.

• Journal of the Mineralogical Society of Korea
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• v.18 no.2
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• pp.135-144
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• 2005

In the high-Ca limestone zone of the Pungchon Formation of the Lower Chosun Supergroup, cryptocrystalline alterations with reddish brown color occur as fissure-fillings or coatings, which was originated from the upper formation, i. e., the Hwajeol Formation. The precipitates result in degradation and contamination of the high-Ca limestone ore in grade and quality, showing characteristic occurrence and mineral composition typical of suggesting a supergene origin. Chalcedonic quartz, kaolinite, illite, goethite and hematite are constituting a characteristic authigenic mineral assemblage and, in places, smectite is less commonly included in the weathering product. In addition to these authigenic phases, some detrital minerals such as mica and orthoclase constituting relatively coarser grains are also rarely present in the supergene alterations. A rather complex clay facies consisting of kaolinite, illite and smectite in the alterations seems to correspond to the typical clay composition of the reported residual pedogenic soils by limestone weathering. The cryptocrystalline weathering product is partly altered to stilbite, a characteristic hydrothermal zeolite, in places, by the hydrothermal contact of late stage. The time of formation and infiltration of the supergene alterations seems to correspond to the stage just after the epithermal alteration of the Pungchon Limestone, i. e., an early Jurassic age. The supergene alteration, which may imply the stage of uplifting, weathering and erosion of the Chosun Supergroup, appears to have undergone at an oxygen-rich environment in descending water of meteoric origin by means of a chemical leaching and diffusion.

• 한국해양학회지
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• v.22 no.3
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• pp.168-178
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• 1987

A study on the mineralogy and internal features have been carried out on a sample of ferromanganese crust from a Central Pacific seamout. The distribution of manganese mineral vernadite($\delta$-MnO$\sub$2/)in the different layers indicates typical hydrogenous origin under a continuous change of growth conditions during crustal firmation. Various internal structures are discerned within the crust which may be attributed to different growth conditions. The growth structure changes and the distinct break in the formation of the crust at about 2 depth are assumed to be the results of Miocene to mid-Pleistocene global palaeoceanographic events.

• The Korean Journal of Quaternary Research
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• v.25 no.2
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• pp.17-24
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• 2011

We investigated the variation of $CaCO_3$ contents in cores PC1 and PC2 recovered from the continental slope area of the Ulleung Basin in the East Sea. $CaCO_3$ contents of cores PC1 and PC2 varied between 0.6 and 17.2% and between 0.3 and 43.0%, respectively. $CaCO_3$ contents in the upper part of core PC1 corresponding to MIS 1 are less than 5%, whereas those in the lower part of MIS 2 are more than 10%. Such variation of $CaCO_3$ contents in core PC1 confirms the previous results of $CaCO_3$ studies in the East Sea. In core PC2, $CaCO_3$ contents of the upper part are similar to those of core PC1. However, $CaCO_3$ contents in the lower part of core PC2 are more than 40%. According to XRD operation and SEM examination, the high $CaCO_3$ contents in the lower part of core PC2 are more attributable to the authigenic carbonate minerals rather than the biogenic carbonate composition. Such abundant authigenic carbonate minerals are closely related to the dissociation of methan hydrates which were observed in the Ulleung Basin.

• Economic and Environmental Geology
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• v.29 no.4
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• pp.421-428
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• 1996

The occurrence, optical property, chemical composition, crystal structure and formation environments of the phillipsite within deep-sea manganese nodules were systematically investigated in this study. Phillipsite in manganese nodules occurs in nucleus of nodules along with consolidated bottom sediments, weathered volcanic debris, and interstitial grains in the each layer of manganese encrusts. Phillipsite is predominantly pseudomorphs of volcanic shards, and occurs as white to pale yellow in color lath-shaped and equant crystals. These show aggregations of prismatic, blocky, and bladed of 2 to $20{\mu}m$ long, and 2 to $5{\mu}m$ thick. The simplified average chemical formula of phillipsite is $({Ca_{0.1}Mg_{0.3}Na_{1.1}K_{1.5}})_3{(Fe_{0.3}Al_{4.2}Si_{11.8})O_{32}{\cdot}10H_2O}$ with a very siliceous and alkalic. The $Si/(Al+Fe^{+3})$ ratio is 2.37 to 2.78 and alkalis greatly exceed the divalent exchangeable cations, and Na/K ratio is 0.59 to 0.81. The phillipsite is monoclinic ($P2_l/m$) with the unit-cell parameters, $a=10.005{\AA}$, $b=14.129{\AA}$, $c=8.686{\AA}$, ${\beta}=124.35^{\circ}$, and $V=1013.6{\AA}^3$. Phillipsites in manganese nodules formed apparently authigenically at a temperature less than $10^{\circ}C$, and they crystallized at a pressure of less than 0.7 kb, and pH of about 8 in deep-sea environments.

• 한국해양학회지
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• v.22 no.3
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• pp.119-129
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• 1987

Sediments in the cores from the KONOD-1 area consist mainly of authigenic smectite and clinoptilolite, and terrigenous minerals of illite, chlorite, kaolinite, quartz, and plagioclase. The authigenic minerals become dominant over the terrigenous minerals with increasing depth. Clinoptilolite occurs at the deeper core depth because its formation is slower than that of smectite. The vertical distribution of minerals indicates that the eolian influence, probably in the late Oligocene, diluted the abundance if smectite in near-surface sediments. This vertical distribution pattern may also have been affected by progressive dissolution of authigenic minerals in the near surface sediments.