• The Journal of the Petrological Society of Korea
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• v.18 no.4
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• pp.315-336
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• 2009

We have studied the orientational characteristics of microcrack frequency, it's length and density in Tertiary crystalline tuff from the northeastern part of the Gyeongsang Basin. 134 sets of microcracks on horizontal surfaces of 3 rock samples from Heunghae-eup were distinguished by enlarged photomicrographs of the thin sections. The variability in patterns among microcrack length-frequency histograms for three rock samples from different altitudes were derived. The pattern of histograms changes progressively from negative exponential form to log-normal form in proportion to altitude. The distribution pattern for rock sample no.1 from lower altitude shows the broad length distribution characterized by higher mean and median, and higher standard deviation. Meanwhile, this distribution pattern corresponds with characteristics of joint length distribution in sedimentary rocks of the lower part of the Gyeongsang Supergroup. The occurrence frequency of shorter microcracks increases toward both NW and NE directions from the $N0{\sim}10^{\circ}W$, with the dominant direction of $N80{\sim}90^{\circ}W$ and $N80{\sim}90^{\circ}E$, respectively. This distribution pattern represents the relative differences in formation timing among microcrack sets and the result of the new initiation of shorter microcracks. Meanwhile, the longest microcracks within $N60{\sim}70^{\circ}W$($L_{max}$:1.18 mm) and $N0{\sim}10^{\circ}W$($L_{max}$:0.80 mm) directions are seen, but this kind of microcracks are very limited in number. Whole domain of the directional angle($\theta$)-frequency(N), length(L) and density($\rho$) chart can be divided into five sections in terms of phases of the distribution of related curves. From the distribution chart, density curve shows five distinct peaks in the WNW-ESE($N70{\sim}80^{\circ}W$), NS~NNE-SSW($N0{\sim}10^{\circ}W$, $N10{\sim}20^{\circ}E$), ENE-WSW($N50{\sim}60^{\circ}E$), and nearly EW($N80{\sim}90^{\circ}E$) directions, respectively. Especially, main directions of faults correspond with the directional angle showing high density. Consequently, these distribution patterns of density curve reflect the representative maximum principal stress orientations suggested in previous studies.

• Journal of the Korean Society of Earth Science Education
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• v.16 no.3
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• pp.319-327
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• 2023

This study involved 22 students in one class of 4th year science intensive course at B College of Education. We investigated the changes in the acquisition of knowledge in the field of geology and the perception of geological exploration among pre-service teachers. For this study, a period of four weeks was designated for a semester to a geological field trip. For the geological exploration, the Geoparks of City B (Geumjeongsan Mountain, Amnam Park, Igidae, Dusong Peninsula, Jangsan, Taejongdae, and Hwangnyeongsan Mountain) were designated. The concept of geology and rocks has been extracted from the concepts that can be found in the Geopark. The composition of the group was composed of one group of four members autonomously. The other two of the pre-service teachers joined a group of friends with whom they had an affinity. After the geological field trip, the materials were organized by group and PPT presentations were made during the lecture time where all the members could listen. The extent to which the pre-service teachers acquired the concepts of geology and rocks after conducting the geological field trip was interpreted as the result of pre- and post-statistical processing. In addition, we interpreted what kind of perception the pre-service teachers had after the geological field trip as a result of the statistical processing before and after. Based on the results of the study, the following conclusions were drawn: First, it was effective for the pre-service teachers to acquire the concepts of strata and rocks after the geological field trip. The reason for this is that the experience of the pre-service teachers in conducting geological field trips has changed their perception of geological field trips. In addition, it is interpreted that these results were obtained because the pre-service teachers had a high level of interest in geology and rocks. Second, the pre-service teachers were able to gain confidence after the geological field trip. This reason is interpreted as the fact that they were able to gain confidence in geological exploration by exploring and experiencing the sites of the Geopark for each group.

• Journal of the Korean earth science society
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• v.24 no.8
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• pp.691-703
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• 2003

Geological terminology used in Korea which has been politically separated for the last 50 years, were compared. For this study, geological terminology used in 'Geology of Korea' published in North Korea (1996), 'Geology of Korea' published in South Korea (1999) and other geological publications were compared. Among the 1272 geological terminology used in North Korea, 49 are for geochronology, 201 for mineralogy, 199 for petrology, 257 for structural geology, 93 for paleontology, and 473 for general geology. Out of these geological terminology, 657 (51.7%) have the same pronunciation and meaning as those used in South Korea 370 (29.1%) are analogous words, and 245 (19.2%)cannot be understood because of differences in the means of expression. Differences in geological terminology used in the two Koreas are thought to be mainly caused by language used only in North Korea, different foreign language interpretation, different initial law application, new connecting word construction, and influence from different cultures.

• The Journal of the Petrological Society of Korea
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• v.17 no.2
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• pp.51-56
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• 2008

The geologic age of the Okcheon metamorphic belt, used to be a longstanding puzzle, has been settled down to Neoproterozoic to Paleozoic with discovery of fossils and isotopic age dating of metavolcanic rocks. As isotopic ages become accumulated, there appeared a controversy over the age of peak metamorphism in the Okcheon metamorphic belt, i.e., a single late Permian-early Triassic metamorphism (CHIME allanite age and U-Pb age of metamorphic zircon), or earlier independent presence of early Permian metamorphism (U-Pb age of allanite within garnet porphyroblast). If we compare the isotopic ages that can represent metamorphism, the data for the latter have much larger error than those of the former with some overlap considering the error limits. It means that, the former, supported by two independent ages, is considered a better representation for the age of metamorphism of the Okcheon metamorphic belt. Therefore, I propose the idea of early Permian metamorphism should better be reserved until conclusive evidence appears. The late Permian-early Triassic metamorphic age suggest that the effect of continental collision influenced much of the middle part of Korean Peninsula, namely, the Imjingang belt, the Gyeonggi massif and the Okcheon belt.

• The Journal of the Petrological Society of Korea
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• v.8 no.1
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• pp.34-45
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• 1999

Mafic granulite xenoliths are found in precambrian porphyroblastic gneiss of the Mt. Jiri area, SW Sobaegsan massif, Korea. The xenoliths are rounded to ellipsoidal in shape, 50-100 cm in length and coarse-grained with granoblastic and foliated texture. The xenoliths consist of orthopyroxene, garnet, biotite, plagioclase, quartz, ilmenite and secondary orthoamphibole. Orthopyroxene is mostly resorbed and rimmed by coronitic orthoamphiboles. Garnets occur as porphyblasts and are zoned with higher pyrope content in cores than in rims. Geothermo-barometry results yield conditions of about $800-850^{\circ}C$, 6 kb and $500^{\circ}C$, 4 kb for early and retrograde stages of equilibration, respectively. According to available geochronological data, it is suggested that the granulite facies metamorphism occurred prior to 2.1-1.9Ga and that the area was superimposed by the high-grade (over $600-700^{\circ}C$) metamorphism between 1.9-1.7Ga, followed by cooling during uplift.

• The Journal of the Petrological Society of Korea
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• v.18 no.2
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• pp.171-179
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• 2009

LA-ICP-MS U-Pb zircon age was determined from the granite gneiss from Jeungsan-Pyeongwon area located to the west of Pyeongan Basin, North Korea, yielding concordant age of $1,873{\pm}19(2{\sigma})$Ma interpreted as Paleoproterozoic granitic magmatism. Considering relatively precise data reported recently using SHRIMP and LA-ICP-MS, ages around 1,870 Ma have been most frequently reported from Precambrian basement rocks of Korean peninsula, including Yeongnam, Gyeonggi, and Nangnim massifs altogether. Geologic events of this period are interpreted as not only granitic magmatism but also hightemperature regional metamorphism depending on their localities. The magmatic and regional metamorphic events of similar periods have also been reported from neighboring cratons of both North China and South China. Therefore, we need more data and efforts to decipher correlation between Precambrian basements between Korea and China.

• Journal of the Korean Society of Earth Science Education
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• v.10 no.2
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• pp.226-234
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• 2017

The purpose of this study is to investigate the effect of the application of storytelling on pre-service teachers of elementary school who take courses in 'earth's strata and rock' on science teaching concept and science teaching efficacy. The experiment was aimed at one class (32 students) enrolled in the 'earth's strata and rock' course at intensive course through 15 weeks from March to June. The experiment was taking lectures of "earth's strata and rock" for one semester, and the pre-service teachers of elementary school finished class demonstration with storytelling technique by group. The results and analysis of the study were analyzed by the corresponding sample test in before and after the group test. The conclusion of the study is as follows. First, the application of storytelling method on pre-service teachers of elementary school was effective in science concept. teaching efficacy. Second, the application of storytelling method on pre-service teachers of elementary school was effective in science teaching efficacy. Third, the application of storytelling method on pre-service teachers of elementary school responded positively.

• The Journal of the Petrological Society of Korea
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• v.18 no.4
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• pp.349-370
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• 2009

The Mt. Dungjuribong Volcanic Complex located in Gurye-gun, southwest of Ryeongnam massif, composed of Cretaceous andesitic rocks and rhyolite. $SiO_2$ contents of the volcanic rocks range from 52.0 to 78.5 wt.%. The major and trace elements composition, REE patterns and tectonomagmatic discrimination diagrams of volcanic rocks suggest that they are typical of continental margin arc calc-alkaline rocks produced in the subduction environment. The phenocrysts of the volcanic rocks show that they had gone in disequilibrium state, such as reversal zoning and resorbed core of plagioclase, reaction rim around pyroxene and resorbed margins of quartz, which showing the evidence of magma mixing during the evolution of magma.

• The Journal of the Petrological Society of Korea
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• v.2 no.2
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• pp.156-166
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• 1993

The volcanic stratigraphy and geochemistry of the Cretaceous volcanic rocks in the southern part of the Pusan showed that the volcanic rocks of the study area consist of alternating pyroclastic rocks and andesitic lavas, apparently constituting a thick volcanic sequence of a stratovolcano. The andesitic rocks contain augite, plagioclase, and hornblende as phenocrysts. Matrix minerals are augite, magnetite, hornblende, apatite. Mafic minerals, such as chlorite, epidote, sericite, and iron oxides occur as alteration products. Dacitic volcanic breccia and rhyolitic welded ash-flow tuff locally overlie the andesitic rocks. The rocks reported in the previous studies as andesitic breccia and andesite plot in the field of basalt, basaltic andesite, andesite, dacite and rhyolite, based on their chemical compositions. The volcanic rocks of the study area belong to the calc-alkaline series, and the andesitic rocks which are predominant in the area plot to the field of orogenic andesite.

• The Journal of the Petrological Society of Korea
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• v.20 no.4
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• pp.219-230
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• 2011

Jurassic granite from Hapcheon was analysed with respect to the characteristics of the rock cleavage. The phases of distribution of microcracks were well evidenced from the enlarged photomicrographs(${\times}6.7$) of the thin section. The planes of principal set of microcracks are parallel to the rift plane and those of secondary set are parallel to the grain plane. These rift and grain microcracks are mutually near-perpendicular on the hardway planes. Consequently the rock cleavage of Jurassic granite from the studied quarry can be related to the preferred orientation of microcracks. Microcrack parameters such as number, length and density show an order of rift > grain > hardway. These results indicate a relative magnitude of the rock cleavage. Meanwhile, brazilian tensile strengths were measured with respect to the six directions. The results revealed a strong correlation between mechanical property with microcrack parameters.