• The Journal of the Petrological Society of Korea
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• v.8 no.3
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• pp.183-202
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• 1999

The Sobeaksan Gneiss Complex in the Punggi area is composed of mainly mignatitic gneiss, porphyroblastic gneiss, garnet granitic gneiss and biotitie granitic gneiss. Metamorphic grade increase gradually from the amphibolite facies of northwestern part to the granulite facies of southwestern part in the study area. Representative mineral assemblage in the amphibolite facies is biotite-muscovite-K-feldspar-plagioclase$\pm$garnet$\pm$epidote, needle shape or fibrous sillimanite occur in transitional zone from the amphibolite facies to the granulite facies. In the granulite facies, the garnet-Opx granulite shows garnet-orthopyroxene-biotite-plagioclase, the metabasite shows clinopyroxene-plagioclase$\pm$hornblende$\pm$orthopyroxene$\pm$garnet and the migmatitic gneiss shows garnet-biotite-sillimanite-cordierite$\pm$spinel as representative mineral assemblage. Retrograde metamorphism after the granulite facies metamorphism made corindum and andalusite in the migmatitic gneiss and the thin layer garnet between clinopyroxene and plagioclase in the metabasites. The peak P-T conditions of the migmatitic gneiss and the garnet-Opx granulite are $916^{\circ}C$/6.6 kb and $826^{\circ}C$/6.3 kb, respectively. The P-T condition of biotite and plagioclase inclusion, which indicates the progressive condition of the granulie facies, within garnet is $866^{\circ}C$/7.5 kb and that of rim composition of garnet and biotite is $726^{\circ}C$/4.6 kb, which infer the clockwise P-T path of the granulite facies metamorphism. The temperatures caculated by the rim composition of garnet and biotite in the migmatitic gneiss and garnet granitic gneiss have a wide range of $556-741^{\circ}C$, which indicate that the retrograde metamorphism after the granulite facies metamorphism has effected differently. It is difficult to determine the P-T condition of the biotite granitic gneiss because less occurrence and higher spessartine content of garnet. The P-T condition of the thin layered garnet between clinopytoxene and plagioclase in the metabasite is $635-707^{\circ}C$/4.1-5.3 kb. This texture indicates the isobaric cooling(IBC) condition of the retrogressive metamorphism. As a result, the metamorphic evolution of the Punggi area has undergone the isobaric cooling after the granulite facies metamorphism which has undergone the clockwise P-T path.

• Journal of The Geomorphological Association of Korea
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• v.25 no.4
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• pp.21-35
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• 2018

The distribution and size of sandy beaches along eastern Korea has a close relationship with the presence of granite rocks. In general, elongated and wide beaches with abundant sands are likely to develop along the coasts where granitic basic rocks comprise the dominant geology or where a large amount of sands are supplied by streams from inland granitic rocks. Small sandy beaches, in contrast, appear in non-granitic rocks (i.e., under sedimentary and/or metamorphic geology). Hence, large beaches are observed continuously along the shore of Gangwon-do, of which coasts consist predominantly of granitic geology. Such continuity declines from Samcheok city to Pohang city. The rock of Gyeonbuk-do is commonly known as sedimentary, deposited between the late Triassic and the early Tertiary Periods. Because few sands are supplied from the upstream areas, sandy beaches unlikely develop along the coasts of the province, only showing a sporadic, discontinuous distribution under Bulguksa granite, granitic gneiss, and some volcanic rocks. Erosion was rarely observed in the beaches where granitic rocks are distributed, whereas merely five beaches seemed to have undergone some level of erosion in non-granitic regions. This is presumably because a larger amount of sands than that which had been eroded away was replenished in areas under granitic geology, while under non-granitic geology having a deficit in sands, no large sandy beaches had formed at first.

• The Journal of the Petrological Society of Korea
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• v.16 no.1 s.47
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• pp.27-37
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• 2007

Here we discuss a geochemical characterisitc of rare earth element (REE) pattern of a Precambrain leucogranitic gneiss at Imweon, Gangwon Province, Korea. The outcrop includes biotite gneiss xenolith. The leucocratic granite gneiss contacting with biotite gneiss is pegmatitic. However, there is no evidence of contact metamorphism between biotite gneiss and leucocratic-pegmatitic granite gneiss. The leucocratic granite gneiss shows a specific phenomenon of M-type (convex curved) tetrad effect in chondrite-normalized REE patterns with large negative Eu anomaly. The degree of REE tetrad effect in the leucocratic-pegmatitic granitec gneiss is weak and shows partly W-type (concave curved) tetrad effect. The Eu anomaly of leucocratic granite gneiss has close relationship with the degree of tetrad effect as well as Ca/Sr ratio. Our results suggest that the REE tetrad effect from the leucocratic granite gneiss should be formed during differentiation process of granitic magma. We also confirmed that the weathering might affect Eu or Ce anomaly rather than the formation of REE tetrad effect in granitic rock.

• The Journal of the Petrological Society of Korea
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• v.3 no.1
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• pp.49-75
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• 1994

The Hognjesa granitic rocks can be subdivided into biotite granitic gneiss and microcline- perthite granitic gneiss according to their mineralogy and textures, which change gradationally each other. They consist mainly of biotite, muscovite, chlorite, microcline, plagioclase, perthite and quartz accompanied with sillimanite, garnet, and tourmaline in places. The replacement and/or alteration phenomena and relationships of coexisting minerals suggest that the granitic gneisses might be formed by regional metamorphism of upper amphibolite facies and granitization by partial melting accompanied to the regional metamorphism, and again at later effected by regional metamorphism of epidote-amphibolite or greenschist facies. The biotite, muscovite and chlorite formed during these metamorphism, show nearly similar chemical compositions, respectively, regardless to the rock phases and stages of formation. They show relatively stable chemical equilibrium between coexisting pairs. The granitization which formed granitic gneisses may be seemed to occur regionally by partial melting accompanied to the first regional metamorphism.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.101-104
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• 2005

To understand the geologic and hydrogeochemical controls on the occurrence of high fluoride concentrations in bedrock groundwaters in South Korea, we examined a total of 367 hydrochemistry data obtained from deep groundwater wells (avg, depth = 600 m) that were drilled for exploitation of hot springs. The fluoride concentrations were generally very high (avg. 5.65 mg/L) and exceeded the Drinking Water Standard (1.5 mg/L) in 72% of the samples, A significant geologic control of fluoride concentrations was observed: the highest concentrations occur in the areas of granitoids and granitic gneiss, while the lowest concentrations in the areas of volcanic and sedimentary rocks. In relation to the hydrochemical facies, alkaline $Na-HCO_3$ type waters had remarkably higher F concentrations than circum-neutral to slightly alkaline $Ca-HCO_3$ type waters. The Prolonged water-rock interaction occurring during the deep circulation of groundwater in the areas of granitoids and granitic gneiss is considered most important for the generation of high F concentrations. Under such condition, fluoride-rich groundwaters are likely formed through hydrogeochemical processes consisting of the removal of Ca from groundwater via calcite precipitation and/or cation exchange and the successive dissolution of plagioclase and F-bearing hydroxyl minerals (esp. biotite). Thus, groundwaters with high pH and very high Na/Ca ratio within granitoids and granitic gneiss are likely most vulnerable to the water supply problem in relation to the enriched fluorine.

• The Journal of the Petrological Society of Korea
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• v.26 no.4
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• pp.385-398
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• 2017

Jiri Mountain lies in the southwestern portion of the Yeongnam massif, which is one of the Precambrian basement massifs of the Korean Peninsular, consisting essentially of high-grade metamorphic rocks. The geology of the area mainly consists of Paleoproterozoic metasedimentary migmatitic gneisses, granitic gneisses which are classified into granitic gneiss, (K-feldspar porphyroblastic) granitic gneiss and quartzo-feldspathic gneiss, charnockite and anorthosite based on their occurrence and petrographic characteristics. The ages obtained from these rocks mainly span a narrow range between ca. 1,876 and 1,856 Ma although inherited cores of zircons from massive granite gneiss yielded much older age spectrum (>2,029 Ma). The age of major metamorphism is ca. 1850-1840 Ma and the metamorphic condition obtained from mineral assemblages and geothermobarometers is about 4-6 kb and up to $700-750^{\circ}C$. These results indicate that in the area intense granitic magmatism and metamorphism occurred in the deep crust during Paleoproterozoic orogeny. Some younger age of charnockite (1,856-1,865 Ma) and anorthosite (1,861-1,862 Ma) might indicate the beginning of intraplate rifting leading to felsic and mafic magmatism just after the orogeny. In conclusion, the rocks in the Jiri Mountain area which formed at a mid to deep crustal zone provide us windows into the deep crust.

• Economic and Environmental Geology
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• v.31 no.2
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• pp.111-125
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• 1998

Dispersion, migration and enrichment of environmental toxic elements from the Samkwang Au-Ag mine area were investigated based upon major, minor and rare earth element geochemistry. The Samkwang mine area composed mainly of Precambrian granitic gneiss. The mine had been mined for gold and silver, but closed in 1996. According to the X-ray powder diffraction, mineral composition of stream sediments and soils were partly variable mineralogy, which are composed of quartz, orthoclase, plagioclase, amphibole, muscovite, biotite and chlorite, respectively. Major element variations of the host granitic gneiss, stream sediments and soils of mining and non-mining drainage, indicate that those compositions are decrese $Al_2O_3$, $Fe_2O_3$, MgO, $TiO_2$, $P_2O_5$ and LOI with increasing $SiO_2$ respectively. Average compositional ranges (ppm) of minor and/or environmental toxic elements within those samples are revealed as As=<2-4500, Cd=<1-24, Cu=6-117, Sb=1-29, Pb=17-1377 and Zn=32-938, which are extremely high concentrations of sediments from the mining drainage (As=2006, Cd=l1, Cu=71, Pb=587 and Zn=481 ppm, respectively) than concentrations of the other samples and host granitic gneiss. Major elements (average enrichment index=6.53) in all samples are mostly enriched, excepting $SiO_2$, $Na_2O$ and $K_2O$, normalized by composition of host granitic gneiss. Rare earth element (average enrichment index=2.34) are enriched with the sediments from the mining drainage. Minor and/or environmental toxic elements within all samples on the basis of host rock were strongly enriched of all elements (especially As, Br, Cu, Pb and Zn), excepting Ba, Cr, Rb and Sr. Average enrichment index of trace elements in all samples is 15.55 (sediments of mining drainage=37.33). Potentially toxic elements (As, Cd, Cr, Cu, Ni, Pb, and Zn) of the samples revealed that average enrichment index is 46.10 (sediments of mining drainage=80.20, sediments of nonmining drainage=5.35, sediments of confluent drainage=20.22, subsurface soils of mining drainage=7.97 and subsurface soils of non-mining drainage=4.15). Sediments and soils of highly concentrated toxic elements are contained some pyrite, arsenopyrite, sphalerite, galena and goethite.

• Economic and Environmental Geology
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• v.5 no.1
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• pp.1-20
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• 1972

A large anorthositic mass outcropped as mushroom-like body extending up to 46km which occurs in the Hadong kaoline district of southern Korea. The anorthositic mass is in contact with the metamorphic, plutonic and sedimentary rocks. The metamorphic rocks are of granitic gneiss and banded gneiss, etc; the plutonic rocks are of gabbroic and dioritic rocks, schistose granite, syenite, diorite and granite. The sedimentary rocks include siltstone and pebbly sandstone of Lower Gyeongsang System, Cretaceous in age. The anorthositic mass shows a gradational contact with the metamorphic and sedimentary rocks, and is cut by the plutonic rocks except gabbroic and dioritic rocks. The anorthositic mass is leucocratic in the central portion of the mass, and, in turn, grades to rock phases in which ma/ic minerals are irregularly scattered, then to the well-lineated rock and finally to the banded gneiss. Lineation of the anorthositic mass is accordant with that of the surrounding banded gneiss, and the lineation continues toward the gneiss. In some places, the rock phases in which mafics are scattered is gradational with adjacent sedimentary rocks. The anorthositic mass in contact with gabbroic and dioritic rocks shows spotted features. Various replacement features seen under the microscope and paragenetic sequence of the mineral components in the anorthositic rocks cannot be considered as the origin of magmatic crystallization. From the field and microscopic observations, it is concluded that the anorthositic mass was formed from replacement of the metamorphic rocks and plutonic rocks by the anorthositic magma.

• Korean Journal of Environmental Biology
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• v.25 no.3
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• pp.228-238
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• 2007

Calcium plays an important role for the organisms' physiology, reproduction, and growth. Calcium amount and transfer efficiency along trophic levels were compared at two different geological areas, Limestone area (LS) and Granitic Gneiss area (GG) in 1992 and 1993. Biomass and calcium amount of plants, herbivores and carnivores were seasonally measured. The removal sweeping net method was used to collect the quantitative insect samples. Calcium content (mgCa $g^{-1}$ DM) and pH of soil were 4.85 and 7.3 at LS and 0.21 and 7.3 at GG. The calcium transfer efficiencies (%) at LS and CG were 0.2 and 4.2 from soil to plants, 0.002 and 0.02 from plants to herbivores, and 73 and 47 from herbivores to carnivores, respectively. As a whole, the high calcium content of the LS soil reduced the utilization of calcium by plants. The higher trophical levels were, the higher ecological efficiency of the biological levels was. The calcium transfer amount was higher at LS, but its efficiency was rather higher at GG.

• Economic and Environmental Geology
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• v.35 no.4
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• pp.355-368
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• 2002

The multi-storied Daewonsa stone pagoda (Treasure No. 1112) in the Sancheong, Korea was studied on the basis of deterioration and geological safety diagnosis. The stone pagoda is composed mainly of granitic gneiss, partly fine-grained granitic gneiss, leucocratic gneiss, biotite granite and ceramics. Each rock of the pagoda is highly exfoliated and fractured along the edges. Some fractures in the main body and roof stones are treated by cement mortar. This pagoda is strongly covered with yellowish to reddish brown tarnish due to the amorphous precipitates of iron hydroxides. Dark grey crust by manganese hydroxides occur Partly, and some Part coated with white grey gypsum and calcite aggregates from the reaction of cement mortar and rain. As the main body, roof and upper part of the pagoda, the rocks are developed into the radial and linear cracks. Surface of this pagoda shows partly yellowish brown, blue and green patchs because of contamination by algae, lichen, moss and bracken. Besides, wall-rocks of the Daewonsa temple and rock aggregates in the Daewonsa valley are changed reddish brown color with the same as those of the pagoda color. It suggests that the rocks around the Daewonsa temple are highly in iron and manganese concentrations compared with the normal granitic gneiss which color change is natural phenomena owing to the oxidation reaction by rain or surface water with rocks. Therefore, for the attenuation of secondary contamination, whitening and reddishness, the possible conservation treatments are needed. Consisting rocks of the pagoda would be epoxy to reinforce the fracture systems for the structural stability on the basements.