• The Journal of the Petrological Society of Korea
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• v.2 no.2
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• pp.74-94
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• 1993

Metabasites and metapelites in the Mungyong area were intruded by Cretaceous granites with radius of 4-8 km. As the distance from granite body increases, the mineral assemblage of metabasite changes from amphibole + plagioclase through amphibole + plagioclase + epidote to amphibole + plagioclase + epidote + chlorite. The compositional variations of amphibole and plagioclase according to the change of metamorphic grade and bulk rock compositions are very complex. Towards the Mungyong Cretaceous granite body, the mineral assemblage of metapelite changes from chlorite+ muscovite(ch1orite zone) through biotite + chlorite + muscovite(biotite zone) to andalusite+biotite + muscovite${\pm}$chlorite or cordierite+ biotite+ muscovite${\pm}$chlorite(cordierite zone). The estimated metamorphic conditions of cordierite zone are 480~$580^{\circ}C$ 1.5-3.3 kb. The theoretical study on the thermal metamorphism caused by the Cretaceous granite with radius longer than 4 km in the Mungyong area suggests the followings: The degree of metamorphism is mainly determined not by the size of granite body but by the temperature of granite intrusion; The country rocks within 2 km from Cretaceous granite have undergone metamorphism with temperature higher than $500^{\circ}C$, which is consistent with the petrological study in the Mungyong area. Mungyong Cretaceous granite caused a low P/T thermal metamorphism to the country rocks; the amphibolite facies metamorphism to the country rocks within 1-2 km from the granite body and the epidote-amphibolite and greenschist facies metamorphism to the country rocks within 2-5 km.

• Journal of the Korean earth science society
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• v.22 no.1
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• pp.10-19
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• 2001

There are three scoria cones and their eruptive materials in Sarabong-Byeoldobong-Hwabukbong area Cheju Island. And they made complicated volcanic stratigraphy. In Byeoldobong tuff, basalt and granite xenoliths are present. It is presumed that the granite is a kind of basement of Cheju island. And Biseokgeori hawaiite has many kaersutite phenocrysts. Therefore, this area is very important for the study about history of volcanic activity of Cheju island. The lowest beds are Shinheung basalt and Byeoldobong tuff. Byeoldobong tuff has xenoliths of granite and phenocrystalline basalt. After the formation of these rocks, the Hwabukbong volcanism commenced. First of all this volcanism formed Biseokgeori hawaiite that has lots of kaersutite, a member of amphibole group, characteristically. Over this rock, Hwabukbong scoria cone was formed. The next Sarabong volcanism effused Keonipdong hawaiite that has lots of plagioclase and olivine phenocrysts and then Sarabong scoria cone was made up. Basalt xenolith in Byeoldobong tuff is different from Shinheungri basalt with regard to petrography, therefore this offers suggestion about existence of another basalt between basement and Shinheungri basalt. Granite xenolith derived from the basement of this area has features of the Jurassic granite in the Korea Peninsula, for example a lot of myrmekitic texture, microcline, and absolute age (172.4 Ma) by K-Ar method.

• Economic and Environmental Geology
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• v.37 no.2
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• pp.153-171
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• 2004

This study was carried out to define the geochemical and mineralogical relationship between stream sediments and regional geology on upstream of Hahn river area. Geochemical characteristic including for major elements, trace elements and rare earth elements of the South and North Hahn river bed sediments are similar to those of acid igneous rocks which are distributed around both Hahn river basin. The chemical variation of major elements against SiO$_2$ and trace elements contents between South and North Hahn river bed sediments doesn't show the difference. REE patterns of both area show a distinct negative Eu anomaly, but total contents of rare earth elements are higher in North Hahn river sediments than South Hahn river sediments. The heavy minerals in the river bed sediments in this study area are identified as tremolite-actinolite, hematiteㆍmagnetite, common hornblende, ilmenite, garnet, epidote, rutile and sphene. In conclusion, it is elucidated that South and North Hahn river bed sediments are being originated from igneous rocks or metamorphic rocks which contains medium-high grade metamorphic minerals and components of originated from sedimentary rocks those of politic or calcareous rocks are eroded away as solution or suspended load.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.3
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• pp.202-212
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• 1992

This study reports on the genesis and mineralogical characteristics of the clay minerals in the soils derived from the five major parent rocks of granite, granite-gneiss, limestone, shale, and basalt in Korea. The investigation on the mineralogical aspects of primary and secondary minerals of the rocks and coarse fractions in the soils have been already reported. In this report, the identification of clay minerals in the soil clay fractions was done through the analyses of chemical, X-ray diffraction, and thermal methods. The studies showed clearly that much of the clay minerals was evolved by the weathering of primary minerals and some were further developed by the transformation of secondary minerals. Cation exchange capacity(CEC) of the clay fractions increased with higher amotunts of vermiculite, chlorite, and illite, however, decreased with higher hydroxy octahedral sheet within the interlayer spaces of vermiculite even if dominant clay with vermiculite. Feldspars in the granite and granite-gneiss might be completely transformed to kaolin mineral, Illite, chlolrite, and vermiculite formed by the alteration of micas, amphibole, augite, and primary chlorile seem to be subsequently transformed to the mixed layer minerals such as illite/vermiculite, illite/chlorite, and chlorite/vermiculite. These weathering products may be ultimately transformed into kaolin minerals. The smectite minerals in the clay fractions of the soils developed on the limestone are considerably present and they seem to be formed directly by the precipitation from high Mg solution and/or by the transformation of vermiculite from micas and chlorite in the parent materials. Abundant presence of illite in the soil clays developed on the shale is considered to have inherited from the fine particles and more resistant hydrous muscovite. The weathering sequences of the hydrous muscovite were as follows according to the degree of soil development ; hydrous muscovite ${\rightarrow}$ illite/vermiculite mixed layer(Inceptisols, Daegu series) and hydrous muscovite ${\rightarrow}$ illite/vermiculite mixed layer ${\rightarrow}$ vermiculite ${\rightarrow}$ kaolin mineral(Alfisols, Buyeo series). The plagioclase in the basalt might be mostly weathered to kaolin minerais. The augite in the basalt is likely to be transformed through progressive stage of weathering, augite ${\rightarrow}$ chlorite ${\rightarrow}$ chlorote/vermiculite mixed layer ${\rightarrow}$ vermiculite ${\rightarrow}$ kaolin. Another weathering sequence of augite could be expected, augite ${\rightarrow}$ chlorite ${\rightarrow}$ illite by the presence of illite and illite/vermiculite mixed layer in the clay fractions. Vermiculite and gibbsite were quantified from thermogravimetry(TG) and kaolin minerals, from both TG and differerential thermal analysis (DTA). Vermiculite in Jangseong series from the limestone was the dominant clay mineral of 21.7 percent and had a range in the order of 9.2 percent in Buyeo series to 5.4 percent in Daegu series from the shale. The rest soils ranged from 8.8 to 28.3 percent. Kaolin minerals were the dominant clay mineral of 32.7 percent in Asan series from the granite-gneiss and Gueom series of 32.0 percent from the basalt. The soils from the limestone ranged from 9.4 to 14.9 percent. The rest soils ranged from 8.9 to 28.6 percent. Gibbsite were 3.9 and 2.3 percent for Weoljeong and Chahang series from the granite, respectively. In Asan and Cheongsan series from the giranite-gneiss were 1.4 and 4.5 percent, respectively, and 3.6 percent in Jangpa series from the basalt.