• Economic and Environmental Geology
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• v.35 no.2
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• pp.171-177
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• 2002

Two piston-core sediments, obtained from the southwestern margin of the Ulleung Basin in East Sea, are analyzed to investigate the stratigraphy and sedimentary environment of the Late Quaternary. The cores consist mainly of cuddy sediments with silty sands, lapilli tephra and ash layers. The chronostratigraphic correlation with known eruption ages reveals that the core sediments contain the stratigraphic document over the past 46.1 kyr and the sedimentation rates during the last glacial period were relatively higher (12.1-14.9 cm/kyr) than those in pelagic ocean. Several sedimentary facies, mainly affected by turbidity currents, are commonly present in the core interval accumulated during the oxygen-isotope stage 2. Many of horizontal voids, which are thought to have formed by gas expansion, are observed in fore 00GHP-07. The total organic carbon (TOC) contents of the core sediments are noticeably high (average 1 .8%). Particularly, these TOC valuers increased during Termination I, suggesting that dering this time interval the sedimentary environment of the study area was changed to more anoxic.

• Journal of the Korean earth science society
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• v.43 no.5
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• pp.569-578
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• 2022

Oceanic Anoxic Event 2 (OAE2) represents a period of mid-Cretaceous when black shale was deposited worldwide. This short period of perturbations in the global biogeochemical cycles spans the Cenomanian-Turonian boundary, marking the peak of the Cretaceous greenhouse, which is characterized by elevated atmospheric pCO₂, sealevel highstand, and expansion of oxygen minimum zone. Since the pioneering work in the 1970s, numerous studies have investigated the cause and consequences of the event based on geochemical and isotope proxies, and it is now widely accepted that the enhanced primary production and volcanism during the Cenomanian-Turonian boundary interval were the key environmental factors that triggered OAE2. This study briefly reviews previous OAE2 studies of the carbon, sulfur, and trace metal cycles for mechanistic understanding of the biogeochemical processes during the event.

• Economic and Environmental Geology
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• v.24 no.2
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• pp.131-150
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• 1991

The Weolseong diatreme was temporally and spatially related to the intrusion of the Gadaeri granite, and was -mineralized by meteoric aqueous fluids. In the Nokdong As-Zn deposit, pyrite, aresenopyrite and sphalerite are the most abundant sulfide minerals. They are associated with minor amount of magnetite, pyrrhotite, chalcopyrite and cassiterite, and trace amounts of Pb-Sb-Bi-Ag sulphosalts. The AsZn ore probably occurred at about $350^{\circ}C$ according to fluid inclusion and compositional data estimated from the arsenic content of arsenopyrite and iron content of sphalerite intergrown with pyrrhotite + chalcopyrite + cubanite. Heating studies of fluid inclusions in quartz indicate a temperature range between 180 and $360^{\circ}C$, and freezing data indicate a salinity range from 0.8 to 4.1 eq.wt % NaCl. The coexisting assemblage pyrite + pyrrhotite + arsenopyrite suggests that $H_2S$ was the dominate reduced sulfur species, and defines fluid parameter thus: $10^{-34.5}$ < ${\alpha}_{S_2}$ < $10^{-33}$, $10^{-11}$ < $f_{S_2}$ < $10^{-8}$, -2.4 < ${\alpha}_{S_2}$ < -1.6 atm and pH= 5.2 (sericte stable) at $300^{\circ}C$. The sulfur isotope values ranged from 1.8 to 5.5% and indicate that the sulfur in the sulfides is of magmatic in origin. The carbon isotope values range from -7.8 to -11.6%, and the oxygen isotope values from the carbonates in mineralized wall rock range from 2 to 11.4%. The oxygen isotope compositions of water coexisting with calcite require an input of meteoric water. The geochemical data indicate that the ore-forming fluid probably was generated by a variety of mechanisms, including deep circulation of meteoric water driven by magmatic heat, with possible input of magniatic water and ore component.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.4
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• pp.171-179
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• 1999

The $CO_2$-rich waters in the Chojeong area are characterized by low pH (5.0~5.8), high $CO_2$pressure (about 1 atm) and high amounts of total dissolved iou (up to 989 mg/L) and chemically belong to Ca-HC $O_3$type. The oxygen. deuterium and tritium isotope data indicate that the mixing process occurred between $CO_2$-rich water and surface water and/or shallow groundwaters and also suggest that the $CO_2$-rich water has been derived from meteoric waters. According to $\delta$$^{13}$ C values (-8.6~-5.3$\textperthousand$). the $CO_2$ in the water is attributed from deep seated $CO_2$gas. The high dissolved carbon (-14.4~-6.8$\textperthousand$. $\delta$$^{13}$ C) in groundwater of the granitic terrain might be affected by $CO_2$-rich water, whereas the dissolved carbon (-17.9~-15.2$\textperthousand$. $\delta$$^{13}$ C) in groundwater of the metamorphic terrain is likely controlled by soil $CO_2$ and from the reaction with calcite in phyllite. Sulfur isotope data (＋3.5~＋11.3$\textperthousand$,$\delta$$^{34}$ $S_{SO4}$) also support the mixing process between $CO_2$-rich water and shallow groundwater. Strontium isotopic ratio ($^{87}$ Sr/$^{86}$ Sr) indicates that the $CO_2$-rich water (0.7138~0.7156) is not related to vein calcite (0.7184) of Buak mine or calcite (0.7281~0.7346) in phyllite. By nitrogen isotope ($\delta$$^{15}$ $N_{NO3}$) the sources of nitrogen (up to 55.0 mg/L, N $O_3$) in the $CO_2$-rich water are identified as fertilizer and animal manure. It also indicates the possibility of denitrification during the circulation of nitrogen in the Chojeong area. The possible evolution model of the $CO_2$-rich water based on the hydrochemical and environmental isotopic data was proposed in this study. The $CO_2$-rich waters from the Chojeong area were primarily derived from the reaction with granite by supply of deep seated $CO_2$. and then the $CO_2$-rich water was mixed and diluted with the local groundwater.ter.

• Korean Journal of Food Science and Technology
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• v.44 no.4
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• pp.401-410
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• 2012

This study examines the authenticity discrimination of the circulated honey by using stable isotope ratio methods. In the case of domestic honey, the range of ${\delta}^{13}C$ for the samples labeled as pure honey was about -27- -21‰ at the $C_3$ origin, and the range of that for artificial honey was over -19‰ at the $C_4$ origin. The range of ${\delta}^{13}C$ for all imported honey was over -27- -23‰ originating from the $C_3$ plant. According to the nectar-source, ${\delta}^2H$ and ${\delta}^{18}O$ for domestic honey were significantly different for 6 and 5 groups, respectively. However, we could not explain the detailed relationship as well as the geographical feature of ${\delta}^2H$ and ${\delta}^{18}O$. The difference for ${\delta}^2H$ and ${\delta}^{18}O$ in the wide range of latitude, such as between Australia and Canada, was more or less shown. However, it was difficult to find out the trends of ${\delta}^2H$ and ${\delta}^{18}O$ for imported honey versus the geographical information in the similar latitudinal country.

• Economic and Environmental Geology
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• v.21 no.1
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• pp.45-56
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• 1988

Many hydrothermal skarn-type iron ore deposits inchiding Mulgeum, Yangseong, Maeri and Kimhae mines are distributed in the south-eastern Gyeongnam Province, Korea. The deposits are magnetite veins which occurred in propylitized andesitic rock near the contact with late Cretaceous Masanite. Symmetrical zoned skarns are commonly developed around the magnetite veins. The order of the skarn zones from the vein is garnet-quartz skarn, epidote skarn, and epidote-orthoclase skarn. The garnets include isotropic or anisotropic andradite($Ad_{100{\sim}70}$), and the epidotes are composed of pistacite($Ps_{21-31}$). Fe contents of the epidotes generally increase toward the magnetite veins. Epidotes and garnets often show compositional variations from grain to grain, that is, their Fe and Al contents vary inversely. This suggests that the variations depend mainly upon $fo_2$ during the skarnization. Oxygen and carbon isotope analyses of minerals from andesitic rock, micrographic granite, major skarn zones and post-mineralization zones were conducted to provide the information on the formation temperature, the origin and the evolution of the hydrothermal solution forming the iron ore deposits. Becoming more distant from the ore vein, temperatures of skarn zones represent the decreasing tendency, but most ${\delta}O^{18}$ and ${\delta}O^{18}_{H_2O}$ values of skarn minerals represent no variation trend, and also the values are relatively low. Judging from all the isotopic data from the ore deposits, the major source of hydrothemal solution altering the skarn zones and precipitating the ore bodies was magmatic water derived from the more deeply seated micrographic granite. This high temperature hydrothermal solution rising through the fissures of propylitized andesitic rock was mixed with some meteoric water, and the extensive isotopic exchange occurred with the propylitized andesitic rock. During this process, the temperature and ${\delta}O^{18}_{H_2O}$ value of hydrothermal solution were lowered gradually. At the stage of iron ore precipitation, because after all the alteration was already finished, the oxygen isotopic exchange with the wall rock was nearly not taken. The relatively high ${\delta}O^{18}$ and ${\delta}O^{18}_{H_2O}$, and relatively low ${\delta}C^{13}$ values of calcites of post mineralization stage, are the results of leaching of the high ${\delta}O^{18}$ chert xenolith in the andesitic rock and low ${\delta}C^{13}$ andesitic rock.

• 한국해양학회지
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• v.30 no.4
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• pp.302-319
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• 1995

The geochemical properties, sedimentation rates, foraminiferal distributions, and oxygen and carbon isotope records of sediment from Cores S-2 and S-19 were studied to investigate late Holocene paleoceanographic and paleoclimatic changes of the admiralty and Maxwell Bay, King George Island, Antarctica. Total organic carbon contents increased from the lower part to the upper part of Cores S-2 and S-19, whereas calcium carbonate contents decreased from the lower part to the upper part of Cores S-2 and s-19,whereas calcium carbonate contents decreased from the lower part to the upper part of Cores S-2 and S-19. Twenty-seven foraminiferal species were identified, and Globocassidurina biora was mostly a bundant in sediment samples. The sedimentation rates ranged from 24 cm/kyr to 237 cm/kyr based on /SUP 14/C-age dating of G. biora. The sedimentation rates increased rapidly in the upper part of the Cores. б/SUP 18/O values ranged from 0.3% to 6.2% and б/SUP 13/C values ranged from -3.0% to 0.0% with several fluctuations of the values. The lowest part of Core S-2, at 128 cmbsf in depth, had a /SUP 14/C-age of 3,100${\pm}$60 yr B.P. and the lowest part of Core S-19, at 230 cmbsf in depth, of 7,400${\pm}$ yr B.P. The results of geochemical and sedimentological analyses of the core sediments suggested five stages of paleoceanographic and paleoclimatic changes as follows: war,-cold stage of 7,500∼6,500 yr B.P., cold stage of 6,500∼3,600 yr B.P., cold-warm stage of 3,600∼2,770 yr B.P., warm stage of 2,770∼2,380 yr B.P. and cold-warm stage of 2,380∼2,100 yr B.P.

• Economic and Environmental Geology
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• v.32 no.5
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• pp.445-454
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• 1999

The Sanjeon Au-Ag deposit consists of three subparallel hydrothermal quartz-calcite veins which filled fault-related fractures (generally $N20^{\circ}$ to 35"W-trending and $70^{\circ}$ to $80^{\circ}$ SW-dipping) within quartz porphyry. The vein mineralization shows an apparent variation of mineral assemblages with paragenetic time: (1) early, white quartz + pyrite + arsenopyrite + brown sphalerite, (2) middle, white (vein) to clear quartz (vug) + base-metal sulfides + electrum + argentite, (3) late, calcite + pyrite + native silver. Mineralogic and fluid inclusion data indicate that gold-silver minerals were deposited at temperatures from 2l $0^{\circ}$ to $250^{\circ}$ with salinities of 4 to 5 wt. % equiv. NaCl and log fS2 values from -14.0 to -12.2 atm. The linear relationship between homogenization temperature and salinity data indicates that gold-silver deposition was a result of meteoric water mixing. Ore mineralization occurred at pressure conditions of about 70 bars, which corresponds to the mineralization depths of about 260 m to 700 m. There is a remarkable decrease of the calculated 1)180 values of water from 1.3 to -9.7%0 in hydrothermal fluid with increasing paragenetic time. This indicates a progressive increase of meteoric water influx in the hydrothermal system at the Sanjeon deposit. Oxygen-hydrogen, sulfur, and carbon isotope values of hydrothermal fluids indicate that the ore mineralization was formed largely from meteoric waters with the contribution of sulfur and carbon from a deep igneous source.

• Korean Journal of Ecology and Environment
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• v.52 no.3
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• pp.192-201
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• 2019

While a fairly large amount of organic matter is produced daily via phytoplankton photosynthesis in Lake Paldang, South Korea, knowledge of the role of algal-derived organic matter (OM) as a refractory OM source is not adequate. To understand the contribution of algal-derived OM to the refractory pool, biodegradation experiment and $KMnO_4$ oxidation experiment were conducted for 60 days using $^{13}C$ and $^{15}N$ labeled natural phytoplankton assemblage. The assemblage was collected from Lake Paldang on May 20, 2010. The photosynthetically produced total organic carbon ($TO^{13}C$), particulate organic carbon ($PO^{13}C$), and particulate nitrogen ($P^{15}N$) remained at 26%, 20%, and 17% of the initial concentrations, respectively, in the form of non-biodegradable organic matter. In addition, 12% and 38% of $PO^{13}C$ remained after $KMnO_4$ treatment on Day 0 and 60, respectively. These results indicate that photosynthetic products could be an important source of refractory organic matter after microbial degradation. Moreover, the microbially transformed algal-derived OM could contribute to the oxidation rate of the chemical oxygen demand.

• Economic and Environmental Geology
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• v.47 no.4
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• pp.317-333
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• 2014

The Pocheon iron (-copper) deposit, located at the northwestern part of the Precambrian Gyeonggi massif in South Korea, genetically remains controversial. Previous researchers advocated a metamorphosed (-exhalative) sedimentary origin for iron enrichment. In this study, we present strong evidences for skarnification and Fe mineralization, spatially associated with the Myeongseongsan granite. The Pocheon deposit is composed of diverse carbonate rocks such as dolostone and limestone which are partially overprinted by various hydrothermal skarns such as sodic-calcic, calcic and magnesian skarn. Iron (-copper) mineralization occurs mainly in the sodic-calcic skarn zone, locally superimposed by copper mineralization during retrograde stage of skarn. Age data determined on phlogopites from retrograde skarn stage by Ar-Ar and K-Ar methods range from $110.3{\pm}1.0Ma$ to $108.3{\pm}2.8Ma$, showing that skarn iron mineralization in the Pocheon is closely related to the shallow-depth Myeongseongsan granite (ca. 112 Ma). Carbon-oxygen isotopic depletions of carbonates in marbles, diverse skarns, and veins can be explained by decarbonation and interaction with an infiltrating hydrothermal fluids in open system ($XCO_2=0.1$). The results of sulfur isotope analyses indicate that both of sulfide (chalcopyrite-pyrite composite) and anhydrites in skarn have very high sulfur isotope values, suggesting the $^{34}S$ enrichment of the Pocheon sulfide and sulfate sulfur was derived from sulfate in the carbonate protolith. Shear zones with fractures in the Pocheon area channeled the saline, high $fO_2$ hydrothermal fluids, resulting in locally developed intense skarn alteration at temperature range of about $500^{\circ}$ to $400^{\circ}C$.