• The Journal of the Petrological Society of Korea
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• v.9 no.3
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• pp.169-186
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• 2000

The Miocene volcanic rocks in the Dangsari area, eastern part of Ulsan city, are mainly composed of andesite lava flows and pyroclastic rocks. The andesite lavas are identified as two-pyroxone andesite, comprising phenocrysts of augite ($Wo_{43.2}$ $En_{41.0}$ $Fs_{15.8}$ ) and hyperthene ($Wo_{2.7}$ $65.8_{En}$ $_{Fs}$ 31.5). The andesitic pyroclastic rocks are largely composed of pyroclastic breccias with alternating tuff-breccia and lapilli tuff, which showing planar layering, and minor amount of andesitic tuff with thin deposits of interlayered tuffaceous shale. According to the petrochemical data, andesitic rocks belong to medium-K calc-alkaline andesite. The position of bulk composition on the AFM diagram and the presence of normative quartz and hypersthene indicate that the volcanic rocks are calc-alkaline. The trace element composition and REE patterns of andesite, which are characterized by a high LILE/HFSE ratio and enrichment in LREE, suggest that they are typical of continental margin arc calc-alkalic volcanic rocks produced in the subduction environment. On the discrimination diagram, the Dangsari volcanic rocks fall into the fields of subduction related continental margin arc volcanic province. The primary magic melts may be derived from about 15% partial melting of mantle wedge in the upper mantle under destructive plate margin. And the melt evolved to calc-alkaline andesite magma by fractional crystallization and the magma was a little contaminated with crustal materials.

• The Journal of the Petrological Society of Korea
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• v.5 no.1
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• pp.35-51
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• 1996

The granitic rocks in the vicinity of the Mt. Sorak, the northeastern part of the NE-SW elongated Mesozoic granitic batholith in the Kyeonggi massif, consist of granodiorite, biotite granite, two-mica granite and alkali feldspar granite. Variations In major and most trace elemental abundances show a typical differentiation trend in a granitic magma. Granitic rocks all display a calc-alkaline trend in the AFM diagram. Also, In the ACF diagram discriminating between I- and S-type granitic rocks, granodiorite and most biotite granite in the southeastern area represent I-type and magnetite-series characteristics, while most biotire granite and two-mica granite in the northwestern area exhibit S-type and ilmenite-series ones.According to recent studies of the granitle rocks In the Inje-Hongcheon district. all ihe granitic rocks distributed in the northeastern part of the Kyeonggi massif have been classified as late Triassic to early Jurassic Daebo granite. With reference of the formerly published ages, an age oi $125.6{\pm}4.4$ Ma calculated by the slope in the plot of $^{87}Rb/^{86}Sr-^{87}Sr/^{86}Sr$ for the biotite granite samples from the southeastern area is inferred as an emplacement age for the granitic rocks in the vicinity of the Mt. Sorak. On the basis of elemental variations and Sr isotope compositions, an possible evolutional process for the granitic magmas in this area is suggested. The primary magma of I-type and magnetite-series generated about 125 Ma by partial melting of igneous originated crustal materials, might be emplaced and evolved through fractional crystallization, convection and assimilation of the surrounding Precambrian metasediments to become S-type and ilmenlte-serles in the outer area, and then solidified to granodiorite, biotite granite and two-mica granite.At the latest stage, the evolved hydrothermal solution altered the formerly solidified biotite granite to alkali feldspar granite and probably later local igneous activities affected the alkali feldspar granite again.

• Journal of the Mineralogical Society of Korea
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• v.26 no.4
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• pp.263-272
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• 2013

The Taebaegsan region and its vicinities mainly consist of Precambrian granitic gneisses and Cambrian meta-sedimentary rocks. And lots of leucocratic(alkali) granites smaller than the stocks are found here and there. Therefore the presence of leuco-granites is not properly described yet in the former studies. For the effective distinction of several granitic rocks, outcrop characteristics, mineral identification, and petro-chemical properties were studied. Some part of granitc gneisses could be classified into typical metamorphic rocks such as migmatites and banded gneisses. And some shows rather dark appearance with gray quartz and feldspars, and others two mica granites, leucocratic ones etc. But all of leucocratic granites of the region usually show bright milky white to beige color. Since they mainly consist of quartz, feldspars, muscovite, and small amounts of sericites, amphiboles, tourmaline and lepidolite. And all of alkali granites belong to the calc-alkalic, peraluminous and S-type in character. During magmatic differentiation of leucocratic granites, CaO and total Fe contents are clearly decreased than those of the older granitic rocks. On the other hand, magmatic evolution also had induced the greisenization and albitization which enriched the relative amounts of alkali elements such as $K_2O$ and $Na_2O$.

• The Journal of the Petrological Society of Korea
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• v.23 no.4
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• pp.325-336
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• 2014

Even though Mesozoic Mudeungsan tuff, located within Neungju Basin, has been named several rock names, it should be named as Mudeungsan tuff due to several evidences, such as fiamme, welded texture and rock fragments in the Mudeungsan tuff. Volcanic eruption boundary between the Cheonwangbong and Anyangsan areas is not clear, but petrochemical and mineral chemical evidences with different ages indicate clear petrological boundary between Cheonwangbong and Anyangsan. The Mudeungsan tuffs from Cheonwangbong and Anyangsan is welded crystal tuff with dacitic composition and were generated from cogenetic calc-alkaline magma in the volcanic arc environment. Geochemical events indicate that magma beneath Cheonwangbong was seems to have been evolved from the magma beneath Anyangsan due to fractional crystallization dominated by plagioclase.

• Economic and Environmental Geology
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• v.43 no.5
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• pp.477-490
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• 2010

The Gagok stratabound skarn deposit is the result of the intrusion of the Cretaceous granitic pluton into the Paleozoic calcareous rocks. The subvolcanic intrusion ranges in composition from quartz monzonite to granite porphyry with I-type, calc-alkaline and weakly peraluminous characteristics. Both endoskarn and exoskarn are developed at the Gagok Zn-(Pb) deposit, with more exoskarn than endoskarn. Geochemical and mineralogical characteristics in the Seongok and Wolgok orebodies can be treated in terms of self-organization. Sphalerites in the Gagok ore can also incorporate minor amounts of Mn, Cd, Cu and In. Trace element concentrations in different orebodies vary because fractionation of a given element into sphalerite is influenced by formation temperature and the amount of sphalerite in the ore. A group of high In/Zn and Cd/Zn ratios in ores, and low Mn/Fe ratios in sphalerites are correlated with proximal processes of a magmatic source. The pattern of minor/trace element variations in ores and sphalcrites can be used for petrogenetic interprctation, e.g., orebody zonation related to crystallization temperature and fluid d sources.

• Economic and Environmental Geology
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• v.45 no.4
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• pp.465-476
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• 2012

The Anatolia peninsula consists of several continental fragments that include the Pontide Block in north and the Anatolide-Touride Block in south as well as the Arabian Platform in southeast. These continental blocks were joined together into a single landmass in the late Tertiary. During most of the Phanerozoic these continental blocks were separated by paleo-oceans, such as Paleo-Tethys and Neo-Tethys. The Pontide Block in north show Laurasian affinities, and was only slightly affected by the Alpide orogeny; they preserve evidence for the Variscan and Cimmeride orogenies. The Pontic Block is composed of the Strandja, Istanbul and Sakarya zones that were amalgamated into a single terrane by the mid Cretaceous times. The Anatolide-Tauride Block in south shows Gondwana affinities but was separated from Gondwana in the Triassic and formed an extensive carbonate platform during the Mesozoic. The Anatolide-Tauride Block was intensely deformed and partly metamorphosed during the Alpide orogeny; this leads to the subdivision of the Anatolide-Tauride Block into several zones on the basis of the type and age of metamorphism and deformation. The Arabian Platform in southeast forms the northernmost extension of the Arabian Plate that shows a stratigraphy similar to the Anatolide-Tauride Block with a clastic-carbonate dominated Palaeozoic and a carbonate dominated Mesozoic succession. A new tectonic era started in Anatolia Peninsula in the Oligocene-Miocene after the final amalgamation of these continental blocks and plate. This neotectonic phase is characterized by extension, and strike-slip faulting, continental sedimentation, and widespread calcalkaline magmatism, which played a very important role in producing beautiful landscapes of the Anatolia Peninsula today.