• The Journal of the Petrological Society of Korea
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• v.17 no.1
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• pp.16-35
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• 2008

We study metamorphism of metasedimetary rocks and origin and evolution of leucogranite form Samcheok area, northeastern Yeongnam massif, South Korea. Metamorphic rocks in this area are composed of metasedimentary migmatite, biotite granitic gneiss and leucogranite. Metasedimentary rocks, which refer to major element feature of siliclastic sediment, are divided into two metamorphic zones based on mineral assemblages, garnet and sillimanite zones. According to petrogenetic grid of mineral assemblages, metamorhpic P-T conditions are $740{\sim}800^{\circ}C$ at $4.8{\sim}5.8\;kbar$ in the garnet zone and $640-760^{\circ}C$ at 2.5-4.5kbar in sillimanite zone. The leucogranite (Imwon leucogranite) is peraluminous granite which has high alumina index (A/CNK=1.31-1.93) and positive discriminant factor value (DF > 0). Thus, leucogranite is S-type granite generated from metasedimentary rocks. Major and trace element diagram ($R_1-R_2$ diagram and Rb vs. Y+Nb etc.) show collisional environment such as syn-collisional or volcanic arc granite. Because Rb/sr ratio (1.8-22.9) of leucogranites is higher than Sr/Ba ratio (0.21-0.79), leucogranite would be derived from muscovite dehydrate melting in metasedimentary rocks. Leucogranites have lower concentration of LREE and Eu and similar that of HREE relative to metasedimentary rocks. To examine difference of REEs between leucogranites and metasedimentary rocks, we perform modeling using volume percentage of a leucogranite and a metasedimenatry rock from study area and REE data of minerals from rhyolite (Nash and Crecraft, 1985) and melanosome of migmatite (Bea et al., 1994). Resultants of modeling indicate that LREE and HREE are controlled by monazites and garnet, respectively, although zircon is estimated HREE dominant in some leucogranite without garnet. Because there are many inclusions of accessary phases such as monazite and zircon in biotites from metasedimentary rocks. leucogranitic magma was mainly derived from muscovite-breakdown in metasedimenary rocks. Leucogranites can be subdivided into two types in compliance with Eu anomaly of chondrite nomalized REE pattern; the one of negative Eu anomaly is type I and the other is type II. Leucogranites have lower Eu concetnrations than that of metasedimenary rocks and similar that of both type. REE modeling suggest that this difference of Eu value is due to that of components of feldspars in both leucogranite and metasedimentary rock. The tendency of major ($K_2O$ and $Na_2O$) and face elements (Eu, Rb, Sr and Ba) of leucogranites also indicate that source magma of these two types was developed by anatexis experienced strong fractionation of alkali-feldspar. Conclusionally, leucogranites in this area are products of melts which was generated by muscovite-breakdown of metasedimenary rock in environment of continetal collision during high temperature/pressure metamorphism and then was fractionated and crystallized after extraction from source rock.

• Journal of Ginseng Research
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• v.30 no.3
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• pp.137-152
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• 2006

This study is for chemical relationships between ginsengs(2, 3 and 4 yr) and soils from three representative soil types of Keumsan, shale(SL), phyllite(PH) and granite(GR). In the weathered soils, the GR is mainly high. Positive relationships are dominant, and negative correlations are shown in the Y-Nb and Nb-Ta pairs. In the field soils, the GR is high while the SL is low. Regardless of the localities, available correlation relationships are dominant in the GR, and dominant in the 3 year area. In the host rocks, high element contents are shown in the GR. Positive relationships, regardless of the localities, are shown in the Zr-Hf, Ta, Nb-Ta and Hf-Ta pairs. In the ginsengs, chemical contents are distinctive with the different ages. Positive relationships are shown in the Y-Nb pair of the SL, Rb-Y pair of the PH, and Rb-Sr pair of the GR. Relative ratios(GR/SL and GR/PH) of the ginsengs suggest that ginsengs from the GR are higher than those of SL and PH while in the comparisons between PH and SL, 2 year ginsengs are high in the SL and 4 year ginsengs are high in the PH. Relative ratios between weathered and field soils (weathered/field) suggest high element contents in the weathered soils from the SL and PH and in the relative ratios(weathered soil/host rock), high element contents in weathered soils. Relative ratios between field soils and ginsengs(field soil/ginseng), regardless of the ages, show several ten and hundred times, suggestive of high contents in the soils. Comparisons with the overall average contents of each area show differences of several ten to hundred times in the SL and PH, and of several to ten times in the GR. These relationships suggest that contents of the ginsengs from the GR are more similar to the soils relative to those of SL and PH.

• Journal of Environmental Analysis, Health and Toxicology
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• v.21 no.4
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• pp.237-242
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• 2018

Strontium (Sr) commonly exists in rock, groundwater, soil, plants, and animals. The Sr isotope ratio offers important information as a tracer on nature because the Sr isotopic composition is not fractionated by any biological process in these ecosystems. Hence, Sr isotope ratio has been used in several studies on tracing the Sr source for contaminated sites and human migration. In this study, we developed a separation method for Sr content, and then improved Sr isotope analysis using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). A powdered rock standard (NIST 2710a) was used to determine the removal of interference elements (Rb and Ca) and the recovery rate of Sr content. The results ranged from 98% to 106%. Additionally, three standard samples (NBS 987, IAPSO and NIST 1486) were analyzed to evaluate the precision and accuracy of the results. The measured $^{87}Sr/^{86}Sr$ ratio for all the samples were consistent with the reported values, within an error. These results indicate that our established Sr separation and Sr isotope measurement methods are reliable and can hence be useful in the fields of environmental and forensic sciences.

• Journal of the speleological society of Korea
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• v.42 no.2
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• pp.33-40
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• 1995

The Cheonbo gold mine is located approximately 8km northeast of Cheonan in southern part of Korean peninsula. The Cheonbo gold deposits are composed of parallel-filling quartz veins that are associated wi th the Cheonan granite which intruded the surrounding Precombrian metamorphic country rocks. Rb/Sr date of the granitic intrusion is 170${\pm}$0. 3m.y., suggesting a middle Jurassic age for gold mineralization.

• Journal of the Speleological Society of Korea
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• v.34 no.35
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• pp.105-112
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• 1993

The Cheonbo gold mine is located approximately 8km northeast of Cheonan in southern part of Korean peninsula. The Cheonbo gold deposits are composed of parallel-filling quartz veins that are associated with the Cheonan granite which intruded the surrounding Precombrian metamorphic country rocks. Rb/sr date of the granitic intrusion is 170$\pm$0.3m.y., suggesting a middle Jurassic age for gold materialization.

• Economic and Environmental Geology
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• v.30 no.6
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• pp.603-612
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• 1997

Cretaceous sedimentary-volcanoclastic formations of the Kyeongsang Supergroup were intruded by granitic rocks in the late Cretaceous and early Tertiary. In the Euiseong and Shinryeong area, these intrusives have various compositions including gabbro, diorite，biotite granite and feldspar porphyry. Associated volcanic rocks consist of two chemically distinct types: the bimodal suite of basalt and rhyolite in the Keumseongsan caldera, and the felsic suite of andesite and rhyolite in the Sunamsan-Hwasan calderas. Most rocks are subalkaline, and follow a typical differentiation path of the calc-alkaline magma. The granitic rocks can be distinguished chemically from the volcanics by high Zr/Y ratios. Differences in Zr/Y and K/Y ratios between the two volcanic suites can be accounted for by mantle source and fractionation. Chondrite-normalized trace element abundances of granitic rocks are depleted in Th and K, whereas those of the Keumseongsan rhyolites are depleted in Sr and Ti. Rb, La and Ce is enriched in rhyolites of the Sunamsan-Hwasan calderas. $Rb-SiO_2$ and Rb-Y+Nb discrimination diagrams suggest that the intrusives and volcanics have a volcanic arc setting. K-Ar ages indicate four plutonic episodes : diorite (89 Ma), granite (66~62 Ma), granite and porphyry (55~52 Ma) and gabbro (52~45 Ma), and two volcanisms : bimodal basaltic and rhyolitic volcanism (71~66 Ma) in the Keumseongsan caldera, and felsic andesitic and rhyolitic volcanism (61~54 Ma) in the Sunamsan-Hwasan calderas. Geochemical and age data thus suggest that the igneous rocks are related to several geologic episodes during the late Cretaceous to early Tertiary.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.4
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• pp.325-337
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• 2020

The Jurassic granitic rocks in the area of Gwangdeoksan located along the boundary between Hwacheon and Cherwon in northern Gyeonggi Massif consist of two-mica granite, garnet-bearing two-mica granite, mica-granite, and porphyritic biotite granite. These granitic rocks are calc-alkaline series and plotted in peraluminious domain in A/CNK vs. A/NK diagram. Petrographical and geochemical data indicate that the porphyritic biotite granite which intruded at the last period originated from distinct parental magma from two-mica granite, garnet-bearing two-mica granite, and mica-granite. On the basis of Rb/Sr vs. Rb/Ba diagram and Al2O3/TiO2 vs. CaO/Na2O, it is inferred the porphyritic biotite granite originated from protolith with less pelitic composition than 3 other granitic rocks. The enriched values of lithophile elements of Cs, Rb, and Ba and negative trough of Nb, P, Ti on spider diagram suggest that the peraluminous Jurassic granitic rocks in Gwangdeoksan area formed in subduction tectonic environment. Whole-rock zircon saturation thermometer indicates that the granitic rocks in the study area were melted at 692-795℃.

• Economic and Environmental Geology
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• v.23 no.2
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• pp.143-159
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• 1990

There is clear difference in content of the major and trace elements between Masan granites of Cu province and Yucheon-Eonyang granites of Pb-Zn province in the Yucheon Basin: the former has low content in K(2.08%), Na(2.42%) and Rb (127ppm), and high content in Ca(3.75%), Mg(1.42%) and Sr(304ppm) whereas the latter has high content in K(3.56-3.60%), Na(3.05-3.06%) and Rb(144-161ppm), and low content in Ca(0.62-0.96), Mg(0.21-0.26%) and Sr(136-157ppm). Ore metals in granites also show slight difference between two areas: Masan granites have slightly higher Cu content(18ppm) than Yucheon-Eonyang granites(13, 14ppm), whereas Yucheon granite(29ppm) has slightly higher Pb content than Masan granites(25ppm). Thus, it may be possible to apply geochemical difference of the granites to distinguish whether a Cretaceous granite mass is related to copper or lead-zinc mineralization, and whether it belongs Cu-province or Pb-Zn province in the Yucheon Basin.

• Economic and Environmental Geology
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• v.40 no.2 s.183
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• pp.223-236
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• 2007

The eastern extension of the Cordilleran-type orogenic belt continues from southeastern China to the Chukot Peninsula through the Korean Peninsula. The Gyeongsang basin, located in the southeastern part of the Korean Peninsula and the Inner Zone of southwest Japan are characterized by extensive distribution of Cretaceous to Tertiary I-type calc-alkaline series of intrusive rocks. These intrusive rocks are possibly the result of intensive magmatism which occurred in response to the subduction of the Izanagi Plate beneath the northeastern part of the Eurasian Plate. The Jindong granitoids within the Gyeongsang basin are reported to be adakites, whose signatures are high $SiO_2,\;Al_2O_3$, Sr, Sr/Y La/Yb and, low Y and Yb contents. The major and trace element contents of the Jindong granitoids fall well within the adakitic field, whereas other Cretaceous granites in the same basin are plotted in the island arc ADR area in discrimination diagrams. Chondrite normalized REE patterns show generally enriced LREEs (La/Yb)C = 3.6-13.8) and slight negative to flat Eu anomalies. The mean Rb-Sr whole rock isotopic age of the Jindong granitoids is $114.6{\pm}9.1$ Ma with an initial Sr isotope ratio of 0.70457. These values suggest that the magma has mantle signature and intruded into the area during Early Cretaceous. The Jindong granitoids have similar paleogeographical locations, paleotectonic environments and intrusion ages to those of the Shiraishino granodiorites of Kyushu Island and the Tamba granitoids of San'yo belt located on southwestern Japanese arc.

• The Journal of the Petrological Society of Korea
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• v.1 no.2
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• pp.132-137
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• 1992

Review of metamorphic terms and rock names from various published articles in Korea reveals that they have often been misused and they may lead to a faulty results in the interpretations of the geologic mass. Their usage can be classified into several groups. A few simple rules are proposed for use in naming metamorphic rocks. The new rock names make by the proposed rules are listed as table with old names.