• Economic and Environmental Geology
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• v.11 no.2
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• pp.47-57
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• 1978

The study focused on the petrology and petrochemistry of the so called "Ganghwa syenitic rocks" which intruded into metasediment of basement in southeastern part of Ganghwa Island. The geologic sequence of the mapped area was shown in table 1, 10 model analyses and 7 chemical analyses on the rock samples taken from the Ganghwa syenitic rocks and Manisan granite have been used to discuss the nomenclature of the rocks and petrological relationship between rock types. The petrograpical and petrochemical features based on, the analyses are as follows: 1) Ganghwa syenitic rocks consist of Ganghwa alkali syenite and Ganghwa diorite porphyry which based on the classification of the subcommision on systematics of igneous of IGUS. Ganghwa diorite porphyry which occured as dike forms are intruded into Ganghwa alkali syenite. The rock forming minerals of Ganghwa alkali syenite are composed of perthite, plagioclase, quartz, hornblend and chlorite in major, and zircon, apatite, sericite and magnetite in minor. Ganghwa diorite porphyries consist of plagioclase, biotite, hornblend, orthoclase and chlorite, with, porphyritic texture. 2) In silica-oxides variation (Fig. 2) and AMF diagram (Fig_ 3), the Ganghwa alkali syenite is similar to the trend of Daly's average basalt-andesite-dacite-rhyolite than Skaergaard which shows the trend of the fractional crystallization of magma, and equivalent to the alkali rock series by Peacock. 3) The general trend of data points shift to plagioclase, and are superimposed on the alkali rich terminal part of the granodiorite province of SW Finland in normative Q-Kf-Pl(Fig. 4) and Or-Ab-An diagram respectively. The above-mentioned evidences suggested that the Ganghwa syenitic rocks are the differential products resulted by assimilation of intermediated magma and metasedment rock under relatively rapid cooling condition.

• Journal of the Speleological Society of Korea
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• v.14 no.15
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• pp.42-90
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• 1987

Lee, Moon Won reported by 63 kinds lescribing the petrography and bulk chemical Composition in Petrology of Cheju volcanic island. The total Chemical Composition data was analyzed by the program of FORTRAN77. First, the Conversition equations and the scatter diagram were examined to the analysis, by the least square method. Next, a statistical data requested a mean Value, maximum value, minimum value, the range, the standard deviation, the variance, the Standord Error and the Coefficient of variation. In the standard deviation, a small Composition is MnO and P$_2$O$\sub$5/, a large Composition is SiO$_2$, Mgo and FeO. The Standard error and the variance were the tandency looked like the Standard deviation well. However, the Coefficient Variation differs from the Standard deviation. Where, a large Coefficient of variation are H$_2$O$\^$-/ and H$_2$O$\^$+/, a small Coefficient of variation are Al$_2$O$_3$ and SiO$_2$. The Correlation of Coefficient Can be Calculated numerically from the relation between SiO$_2$, Al$_2$O$_3$ and TiO$_2$ to other Compositions.

• Korean Journal of Mineralogy and Petrology
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• v.34 no.4
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• pp.293-311
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• 2021

The volcanic rocks that make up Yeongdo island, an administrative district located on the southern coast of Busan, are composed of andesitic and rhyolitic rocks. Andesitic rock is mainly composed of volcanic breccia has a phenorysts of plagioclase and contains rock fragments. The rhyolitic rock is composed of volcanic angular rock at the base of Mt. Bongnae, and welded tuff forms the main mass of Mt. Bongnae. The fiamme structure can be easily observed with the naked eye, and the higher the altitude, the weaker the welded structure develops and the less the amount of rock fragments and crystals constituting the welded tuff. It is indicated that the magma that formed this study area is related to the tectonic environment of the continental margin related to subduction, and that it erupted after undergoing fractional cystallization at the same time with some contaminant in the continental crust. As a result of analyzing the main elements by altitude, it is believed to be the result of mixing at least 4 times or more of magma batches.

• Communications for Statistical Applications and Methods
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• v.19 no.4
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• pp.559-569
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• 2012

Compositional data consist of compositions that are non-negative vectors of proportions with the unit-sum constraint. In disciplines such as petrology and archaeometry, it is fundamental to statistically analyze this type of data. Aitchison (1983) introduced a log-contrast principal component analysis that involves logratio transformed data, as a dimension-reduction technique to understand and interpret the structure of compositional data. However, the analysis is not usable when zero values are present in the data. In this paper, we introduce 4 possible methods to reduce the dimension of compositional data with zero values. Two real data sets are analyzed using the methods and the obtained results are compared.

• Economic and Environmental Geology
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• v.23 no.3
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• pp.343-352
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• 1990

The Cretaceous granites are widely distributed in the studied area, Mungyeong-Sangju, which belongs to the southwestern part of the Ogcheon Folded Belt. The granites are characterized by medium-coarse grained, spotted miaroles, partly flow textures of biotite, aplitic dykes and pegmatitic pockets with druse. From the major compositions, the granites indicate peraluminous, calc-alkaline, salic and late stage products of differentiation. In the view of normative compositions of Qz-Ab-Or and perthitic alkali feldspar, they were formed under 1-4kb and $426^{\circ}-456^{\circ}C$ in acqueous conditions. The K/ Ar biotite age shows $72{\pm}1$ Ma for this grante, corresponding to the igneous activity of the Bulgugsa Disturbance periods in the area. The above results represent that these granite bodies are differentiated from a single magma.

• The Journal of the Petrological Society of Korea
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• v.8 no.1
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• pp.1-13
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• 1999

The Latite Ridge Latite in the East Tintic volcanic field, Utah in USA occurs as a welded ash-flow tuff, has 63.7-66 wt% $SiO_2$ on an anhydrous basis, and shows calc-alkaline affinities. The rocks fall in the trachyte field of IUGS classification. It is characterized by unusally high $K_2O$ content (5.9-7.6 wt%), relatively high equilibration temperature (950-973$^{\circ}C$), and biotites with high $TiO_2$ content (7.4-8.2wt%). Various differentiation processes were tested using the XLFRAC program to infer the origin of the Latite Ridge Latite. The results suggests that crystal fractionation from shoshonite is one possible process to generate the Latite Ridge Latite. Shoshonite of the East Tintic volcanic field was possibly formed by crystal fractionation from a subduction-related K-, Mg-rich mafic magma.

• Explosives and Blasting
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• v.22 no.2
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• pp.45-54
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• 2004

Samples examined in this study were acquired from Machun building stone, Dukwoo building stone in Kyungnam province The aim of this study is to examine physical features of Machun rock from specific gravity, porosity. absorption, point load test. triaxial compressive test, Brazilian test, petrology test, and chemical analysis test.

• Economic and Environmental Geology
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• v.24 no.1
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• pp.71-79
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• 1991

Anisotropy of magnetic susceptibility (AMS), directional variation of susceptibility in a sample, indicates the relative magnitude and orientation of preferentially aligned magnetic grains in a rock sample and represents important aspects of rock fabrics. This observation leads to various studies which applied the AMS technique to numerous geological problems, especially sedimentology, petrology, structural geology, and tectonics. Since AMS is, relative to conventional methods of petrofabric measurement, quickly measured, easily interpretated, and providing quantitative data, AMS technique has evolved into a powerful tool for detection of rock fabrics and continues to draw the interest of non-specialists as well as magnetists. This paper represents the theory, techniques, and parameters of the relatively new AMS method for estimating petrofabrics and their various applications.

• Economic and Environmental Geology
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• v.21 no.2
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• pp.117-129
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• 1988

The purpose of this study is to determine the stratigraphy of the volcanic rocks in the Chilpo-Weolpo area, the north of Pohang basin, based on field survey and lithological properties of the rocks. The volcanic pile(Chilpo tuff) overlies the Cretaceous sedimentary formation and is unconformably overlain by the Miocene Yeonil Group. The Chilpo tuff comprises a thick sequence(>200m) of pyroclastic flow deposits. Five members are distinguished, each representing separate flow units, comprising none(or weakly) to densely welded rhyolite tuff. The Chilpo tuff consists of, in ascending order, greenish weakly welded tuff, volcanic conglomerate, alternation of tuff breccias and fine tuffs, greenish none to densely welded tuff and red-brownish densely to weakly welded vitric tuff. This study revealed that the volcanic rocks in this area were formed by 4 volcanic stages. On the basis of K-Ar age($44.7{\pm}1.1\;Ma$) and lithologic data, geological age of the Chilpo tuff may be Eocene.

• The Journal of the Petrological Society of Korea
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• v.14 no.4 s.42
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• pp.212-225
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• 2005

This study has been designed to elucidate the morphology of Jisagae columnar joints and the petrography and petrochemistry of Daepodong basalt in Jeju Island, distributed along the 3.5 km-long coast from Seongcheonpo to Weolpyeongdong. Colonnade of the Jisagae columnar joint typically occurs within the upper part of a flow and consists of relatively well-formed basalt columns. Most columns are straight with parallel sides and diameters from 100 cm to 205 cm, $130\~139\;cm$ in maximum. Length of the columns extends up to 20 m. Most columns tend to have 6 or 5 sides but sometimes they have as few as $3\~4$ or as many as 7 or 8 sides. The Daepodong basalt consists of plagioclase, olivine, orthopyroxene, clinopyroxene, ilmenite and magnetite. Plagioclase is labradorite, clinopyroxene is augite, orthopyroxene is bronzite and olivine is chrysolite and hyalosiderite. The Daepodong basalt shows porphyritic texture with matrix of mainly intersetal texture. The Daepodong basalt is plotted into alkali rock series on the TAS diagram. The tectonic setting of the Daepodong basalt represents within plate environment.