• Economic and Environmental Geology
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• v.31 no.3
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• pp.171-183
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• 1998

Early Tertiary volcanics, volcanoclastics and granodiorite occur in the Barton Peninsula, King George Island, Antarctica. In the granodioritic stock and volcanic rocks, propylitic alteration characterized by actinolite, epidote, chlorite and calcite is widespread, and disseminations and veinlets of sulfide minerals such as pyrite, chalcopyrite and bornite are ubiquitious. The study on the hydrothermal alteration near granodioritic stock can be summarized as follows; (1) granodiorite intrusion is a small, high level stock associated with calc-alkaline volcanism, and have high copper content, (2) high temperature type of propylitic alteration and common occurrence of copper sulfides in and around granodiorite intrusion, (3) low ${\delta}^{34}S$ values of pyrites by oxidational conditions of sulfide deposition, (4) low ${\delta}^{34}S$ values of quartz and feldspar in the granodiorite, and isotopic non-equilibrium by hydrothermal alteration. It suggest that hyrothermal alteration and mineralization near granodioritc stock should be genetically related to granodiorite intrusion in the Barton Peninsula.

• Korean Journal of Environmental Agriculture
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• v.11 no.1
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• pp.26-40
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• 1992

Cheju Island formed by Quarternary volcanism provides highly permeable hydrogeological environment. To meet the increasing demand of water in the island, many groundwater wells have been developed. The environmental isotopes(oxygen-18, deuterium, tritium) and chemical analysis of water samples from the eastern part of the island were carried out to ascertain whether groundwater in the eastern part of the island was contaminated by sea water. The result of tritium analysis indicated fast infiltration of meteoric water into underground and rapid mixing process between rain water and groundwater. The results of oxygen-18 and deuterium analysis demonstrated that most of the wells in the eastern part of the island were influenced by sea water intrusion. Chemical analysis of water samples revealed that most groundwater in study area were classified into Na-Cl type and showed high chloride/bicarbonate ratios. Sea water intrusion in the northeastern part of the island has proceeded at least 3 km within the coastaline, and in the south eastern part about 700m.

• 한국해양학회지
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• v.24 no.2
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• pp.69-78
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• 1989

Cultivated pearls, composed of aragonite crystals, show two distinctive layers: nacreous and conchiolin organic layers. Each aragonite crystal is surrounded by organic matrix, which probably consists of amino acids. Nucleus, surrounded by pearl layer, also consists of nacreous crystals, suggesting that there is a close mineralogical and ultrasturctural relationship between pearl and nucleus. Carbon isotopic values of cultivated pearls are within the range of marine carbonate carbon. Oxygen isotopic composition indicates that the temperature for the growth of pearl and pearl oyster ranges from 16.4 to $21.4^{\circ}C$ and from 15.5 to $24.8^{\circ}C$, corresponding to the summer temperature range of the cultivating area. Elemental composition of pearl, pearl oyster, and nucleus shows that there is a difference in chemical composition depending upon the original mineralogy and the chemical composition of water in which shells grow. Especially, a strong relationship exists between pearl and the inner layer of pearl oyster because both are composed of nacreous aragonite and formed in a shallow marine environment.

• Economic and Environmental Geology
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• v.51 no.6
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• pp.567-577
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• 2018

One of problems related with water curtain cultivation (WCC) in Korea includes severe declination of groundwater levels during the peak season, and it is likely that the problem can be resolved efficiently when the connection characteristics between groundwater and stream are well understood. This study examined temperature, and oxygen/hydrogen stable isotopic compositions of the flowing groundwater to understand the connection between stream and ground water, and the influence of stream water on the nearby aquifer. This study was performed in Wangjeon-ri (Kwangseok-myon, Nonsan City), the well-known strawberry town using WCC technique. The sampling was done during February 2010 through June 2011 for both groundwaters and nearby streams. Temperature distribution pattern indicates that stream widely affected groundwater in the right part of WCC ara. In the left part, the influence of stream seems to occur narrowly near the stream. The similar phenomenon is reflected in the oxygen and hydrogen isotopic data.

• Ocean and Polar Research
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• v.30 no.3
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• pp.249-258
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• 2008

Oxygen isotopic composition(${\delta}^{18}O$) of walleye pollock, Theragra chalcogramma, otoliths were measured to investigate interannual and regional correlation with habitat temperature. Specimens were collected from fishermen in Korea and Japan between $1997{\sim}1999$, while seawater temperatures were obtained from Korean and Japanese Oceanographic Data Centers. Seawater temperature was generally lower off the eastern Korean Peninsula than off eastern Hokkaido(Japan). Sagittal otoliths were removed for measurement of ${\delta}^{18}O$ using a micro-drilling technique. In most cases, ${\delta}^{18}O$ and habitat temperature exhibited negative relationship in Korean and Japanese waters. Higher ${\delta}^{18}O$ was observed in Korean pollock compared to Japanese pollock. The marginal parts of otoliths exhibited higher ${\delta}^{18}O$ than cores from both regions. This is an indication that somatic growth of walleye pollock occurs in deeper and cooler waters. Interannual variation in ${\delta}^{18}O$ was also observed. Mean ${\delta}^{18}O$ values acquired from 1997 otoliths were lower(2.15%) than those of 1998(2.67%) and 1999 (2.65%) in Korean pollock. These measurements coincided with changes in observed temperature in Korean waters, in which mean seawater temperature was warmer in 1997 than in 1998 and 1999. In Japanese waters, mean seawater temperature was lowest in 1997, which coincided with highest ${\delta}^{18}O$ values in the same year.

• The Journal of the Petrological Society of Korea
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• v.20 no.4
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• pp.191-206
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• 2011

The emplacement ages, whole-rock geochemistry and Sr-Nd isotopic compositions of granitoid rocks from Cheongju area, South Korea, were investigated for delineating their petrogenetic link to the Jurassic Daebo granitoid rocks. Zircon crystals were collected from the diorite, biotite granite and acidic dyke samples in a single outcrop. Cross-cutting relationships show that the emplacement of diorite was postdated by the intrusion of biotite granite. Both rocks have been subsequently intruded by acidic dyke. The U-Pb isotopic compositions of zircon from the diorite, biotite granite, and acidic dyke were measured using a SHRIMP-II ion microprobe, yielding the crystallization ages of $174{\pm}2Ma$, $170{\pm}2Ma$, and $170{\pm}5Ma$, respectively, with 95% confidence limits ($t{\sigma}$). The emplacement ages are consistent with those determined from the above relative ages. The major and trace element patterns of the rocks are consistent with those of the Jurassic Daebo granitoid rocks, possibly suggesting a subduction-related I-type granite. The geochemical signature is, however, betrayed by the Sr and Nd isotopic compositions of these rocks. The isotopic signatures suggest that the rocks were produced either by the partial melting of lower-crust or by the mantle-derived magma contaminated by the basement rocks during its ascent and/or emplacement. In addition, the inherited ages of zircons of the rocks (ca. 2.1, 1.8, 0.8 and 0.4 Ga) suggest a possible assimilation with crustal rocks from the Gyeonggi massif and Ogcheon metamorphic belt.

• Economic and Environmental Geology
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• v.41 no.1
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• pp.15-32
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• 2008

The hydrochemical and isotopic (stable isotopes and noble gas isotopes) analyses for hot spring waters, cold groundwaters and surface water samples from the Seokmodo hot spring area of the Ganghwa province were carried out to characterize the hydrogeochemical characteristics of thermal waters and to interpret the source of thermal water and noble gases and the geochemical evolution of hot spring waters in the Seokmodo geothermal system. The hot spring waters and groundwaters show a weakly acidic condition with the pH values ranging from 6.42 to 6.77 and 6.01 to 7.71 respectively. The outflow temperature of the Seokmodo hot spring waters ranges from $43.3^{\circ}C\;to\;68.6^{\circ}C$. Relatively high values of the electrical conductivities which fall between 60,200 and $84,300{\mu}S/cm$ indicate that the hot spring waters were mixed with seawater in the subsurface geothermal system. The chemical compositions of the Seokmodo hot spring waters are characterized by Na-Ca-Cl water type. On the other hand, cold groundwaters and surface waters can be grouped into three types such as the Na(Ca)-$HCO_3$, Na(Ca)-$SO_4$ and Ca-$HCO_3$ types. The ${\delta}^{18}O\;and\;{\delta}D$ values of hot spring waters vary from -4.41 to -4.47%o and -32.0 to -33.5%o, respectively. Cold groundwaters range from -7.07 to -8.55%o in ${\delta}^{18}O$ and from -50.24 to -59.6%o in ${\delta}D$. The oxygen and hydrogen isotopic data indicate that the hot spring waters were originated from the local meteoric water source. The enrichments of heavy isotopes ($^{18}O\;and\;^2H$) in the Seokmodo hot spring waters imply that the thermal water was derived from the diffusion Bone between fresh and salt waters. The ${\delta}^{34}S$ values ranging from 23.1 to 23.5%o of dissolved sulfate are very close to the value of sea water sulfate of ${\delta}^{34}$S=20.2%o in this area, indicating the origin of sulfate in hot springs from sea water. The $^3H/^4He$ ratio of hot spring waters varies from $1.243{\times}10^{-6}\;to\;1.299{\times}10^{-6}cm^3STP/g$, which suggests that He gas in hot spring waters was partly originated from a mantle source. Argon isotopic ratio $(^{40}Ar/^{36}Ar=298{\times}10^{-6}cm^3STP/g)$ in hot spring waters corresponds to the atmospheric value.

• Journal of the Korean earth science society
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• v.33 no.6
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• pp.481-496
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• 2012

REE, major and trace elements, and Sr-Nd isotopic ratios of surface sediments around Jeju Island were analyzed for identifying the origin of the sediments. The Chemical Index of Alteration (CIA) between 44.2 to 68.9 (av. 59.4) shows a similarity with the Huanghe sediment. The most sediments found within the study areas show a very similar chondrite-normalized REE pattern that has enriched LREE ($La_{(N)}/Sm_{(N)}$ >3) and small negative Eu anomaly, typically of average shales. The UCC-nornalized REE patterns of the southwestern offshore sediment samples show a very similar pattem with the Changjiang sediment with enriched in most REE and more convex REE pattern than those of the Huanghe and Keum rivers sediments, which indicates that the Changjiang River's suspended sediments have been transported into the western part of Jeju Island. The $^{87}Sr/^{86}Sr$ isotopic ratios vs ${\varepsilon}_{Nd}(0)$ values were thus used as a tracer to discriminate the provenance of sediments in the study area. Based on the discriminated diagram, it clearly showed that most sediments in the western and northwestern part were closely plotted with sediments of the Huanghe River. However, the sediments in the southwestern part near the Changjianf estuary were closely plotted with submerged delta sediments of the Changjiang River. In contrast, the sediment samples of the northeastern part showed discriminative figures from those of the Chinese rivers. It suggests that sediments around Jeju Island must be originated from diverse sources.

• Korean Journal of Ichthyology
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• v.34 no.2
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• pp.102-112
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• 2022

This study investigated dietary habits and intra- and inter-specific food resource partitioning of co-occurring walleye pollock (Gadus chalcogrammus) and Pacific cod (G. macrocephalus) from the waters off the north-eastern coast of South Korea using stomach contents and stable isotopes (δ¹³C and δ¹⁵N) analyses. Both species are mesopelagic carnivores that consumed mainly benthopelagic crustaceans, but teleosts were also abundant in the diet of Pacific cod. Non-metric multidimensional scaling (nMDS) ordination and permutational multivariate analysis of variance (PERMANOVA) of dietary data revealed significant intra- and inter-specific dietary differences, i.e., food resource partitioning. Nitrogen stable isotope values (δ¹⁵N) were similar between walleye pollock and Pacific cod, but carbon stable isotope values (δ¹³C) were significant different, suggesting different trophic positioning. Canonical analysis of principal coordinate (CAP) ordination plot further demonstrated that differences in the type and range of prey ingested by the two species contributed such an inter-specific difference in the diet compositions. Ontogenetic changes in diet compositions were evident. As walleye pollock, they preyed more upon carid shrimps and cephalopods, but no such trend was observed in the diets of Pacific cod. While stable isotope values indicated that large-sized specimens of both species were significantly enriched in ¹⁵N relative to smaller conspecifics thus supporting these data. Consequently, in this study, both methodologies, i.e., stomach contents and stable isotope analyses, provided evidence of inter- and/or intra-specific dietary segregations and trophic niche partitioning between co-occurring walleye pollock and Pacific cod off eastern Korean waters.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2015.08a
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• pp.81-88
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• 2015