• The Journal of the Petrological Society of Korea
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• v.23 no.4
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• pp.293-309
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• 2014

The Qinling-Dabie-Sulu-Hongseong-Odesan collision belt was formed by the collision between the North China and South China Cratons during late Permian to Triassic. During the collision, Triassic post-collision igneous rocks regionally intruded in the Qinling and the Hongseong-Odesan collision belts which represent the western and eastern ends of the collision belt, respectively. However, no and minor Triassic post-collision igneous activities occur in the Dabie and Sulu belts respectively. The peak metamorphic pressure conditions along the Qinling-Dabie-Sulu-Hongseong-Odesan belt indicate that the slab break-off occurred at the depth of ultra-high pressure (UHP) metamorphic condition in the Dabie and Sulu belts and at the depths of high pressure (HP) or high pressure granulite (HPG) metamorphic condition in the Qinling and Hongseong-Odesan belts. In the Dabie and Sulu belts the heat supply from the asthenospheric mantle through the gab formed by slab break-off could not cause an extensive melting in the lower continental crust and lithospheric mantle directly below it due to the very deep depth of slab break-off. On the other hand, in the Qinling and Hongseong-Odesan belts, shallower slab break-off caused the emplacement of regional post collision igneous rocks. The post-collision igneous rocks occur in the area to the north of the Mianlu Suture zone in the western Qinling belt and crop out continuously eastwards into the areas to the north of the Shangdan Suture zone in the eastern Qinling belt through the areas within the South Qinling block. This distribution pattern of post collision igneous rocks suggests that the Triassic collision belt in the Mianleu Suture zone may be extended into the Shangdan Suture zone after passing through the South Qinling block instead into the boundary between the South Qinling block and the South China Craton.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.6 no.3
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• pp.217-224
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• 2008

In deep geological disposal system, the integrity of a disposal canister having spent fuels is very important factor to assure the safety of the repository system. This disposal canister is one element of the engineered barriers to isolate and to delay the radioactivity release from human beings and the environment for a long time so that the toxicity does not affect the environment. The main requirement in designing the deep geological disposal system is to keep the buffer temperature below 100$^{\circ}C$ by the decay heat from the spent fuels in the canister in order to maintain the integrity of the buffer material. Also, the disposal canister can endure the hydraulic pressure in the depth of 500 m and the swelling pressure of the bentonite as a buffer. In this study, new concept of the disposal canister for the CANDU spent fuels which were considered to be disposed without any treatment was developed and the thermal stability and the structural integrity of the canister were analysed. The result of the thermal analysis showed that the temperature of the buffer was 88.9$^{\circ}C$ when 37 years have passed after emplacement of the canister and the spacings of the disposal tunnel and the deposition holes were 40 m and 3 m, respectively. In the case of structural analysis, the result showed that the safety factors of the normal and the extreme environment were 2.9 and 1.33, respectively. So, these results reveal that the canister meets the thermal and the structural requirements in the deep geological disposal system.

• The Journal of the Petrological Society of Korea
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• v.4 no.1
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• pp.31-48
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• 1995

The Jurassic Kwanaksan stock, so far known to be composed of biotite granite only, has the mineral assemblage of quartz+K-feldspar+plagioclase+biotite${\pm}$gernet. The lithology of the stock is classified as alkali feldspar granite by their mode and plagioclase compositions (An<5). Subsolvus feldspars, rather early crystallization of biotite, and shallow emplacement depth estimated from Q-Ab-Or diagram suggest hydrous nature of the magma, which contrasts with anhydrous A-type like geochemistry described below. Major and trace element compositions of the Kwanaksan stock are distinct from those of the adjacent Seoul batholith, suggesting a genetic difference between the two, The Kwanaksan stock shows geochemical characteristics similar to A-type granite in contrast to most other Mesozoic granites in Korea, in that it has high $SiO_2$(73~78wt%), $Na_2O+K_2O$, Ga(27~47 ppm). Nb(22~40 ppm), Y(48~95 ppm), Fe/Mg and Ga/Al, and low CaO(<0.51 wt%). Ba (8~75 ppm) and Sr(2~23 ppm). However, it has lower Zr and LREE and higher Rb(384~796 ppm) than typical A-type granite. LREE-depleted rare earth element pattern with strong negative Eu anomaly of previous studies is reinterpreted as representing source magma characteristics. The residual material during partial melting is not compatible with pyroxenes, amphibole or garnet, while significant amount of plagioclase is required. Similarity of geochemistry of the Kwanaksan stock to A-type granite suggests the origin of the stock has a chose relationship with that of A-type granite. These observations lead us to propose that the Kwanaksan stock was formed by partial melting of felsic source rock.

• The Journal of the Petrological Society of Korea
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• v.3 no.1
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• pp.1-19
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• 1994

We present petrography, mode and chemistry data for Fe-Ti oxide minerals from the Mesozoic granitoids in South Korea. Magnetites from the Daebo Uurassic) granites are nearly pure $Fe_3O_4$, while those from the Bulgugsa (Cretaceous) granites contain considerable amounts of Mn and Ti. This is probably related to rapid cooling of the Bulgugsa granites compared with slow cooling of Daebo granites, which is supported by geologic relations and hornblende geobarometry results of Cho and Kwon (1994) on the emplacement depth for these granites. The composition of ilmenite does not shew appreciable difference between the Daebo and Bulgugsa granites. However, $Fe_2O_3$ contents are higher for the ilmenites coexisting with magnetite than for those without magnetite. In the temperature vs. oxygen fugacity diagram, the Bulgugsa granites plot near Ni-NiO and QFM buffer curves, although only two samples show greater than the granite solidus temperature. The mode data suggest that both magnetite- and ilmenite-series exist in Daebo and Bulgusa granites from the Kyonggi massif, Ogcheon belt and Youngnam massif, while only magnetite-series exists in Bulgugsa granites from the Kyongsang basin. Many ilmenite-series granites occur in the Ogcheon belt, which might be related to assimilation of carboniferous sediments in the belt. The proportion (44 : 56) between ilmenite- and magnetite-series for the Daebo granites is significantly different from that of Ishihara et al. (1981) who showed, using magnetic susceptibility data, predominance of ilmenite-series (more than 70%) for the Daebo granites, which can be mainly attributed to preference in sampling and to wrong assignment of age for some plutons. We also found magnetite in weakly-magnetized Kanghwa granite which was formerly classified as ilmenite-series by Ishihara et al. (1981). The proportion of ilmenite-series increases in the order of hornblende biotite granite, biotite granite and two mica granite. We conclude from these observations that the ilmeniteseries granites might have originated from contamination of carboniferous crustal material and/or such source material.

• Economic and Environmental Geology
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• v.35 no.3
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• pp.211-220
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• 2002

The Xiaoxinancha Cu-Au deposit in the Jilin province, located in NNE 800 km of Beijing, is hosted by diorite. The ore mineralization of Xiaoxinancha Cu-Au deposit show a stockwork occurrence that is concentrated on the potassic and phyllic alteration zones. The Xiaoxinancha Cu-Au deposit in the south is being mined with its reserves grading 0.8% Cu, 3.64 g/t Au and 16.8 g/t Ag and in the north, grading 0.63% Cu, 3.80 g/t Au and 6.8 glt Ag. The alteration assemblage occurs as a supergene blanket over deposit. Hydrothermal alteration at the Xiaoxinancha Cu-Au deposit is centered about the stock and was extensively related to the emplacement of the stock. Early hydrothermal alteration was dominantly potassic and followed by propylitic alteration. Chalcocite, often associated with hematite, account for the ore-grade copper, while chalcopyrite, bornite, quartz, epidote, chlorite and calcite constitute the typical gangue assemblage. Other minor opaque phases include pyrite, marcasite, native gold, electrum, hessite, hedleyite, volynskite, galenobismutite, covellite and goethite. Fluid inclusion data indicate that the formation of this porphyry copper deposit is thought to be a result of cooling followed by mixing with dilute and cooler meteoric water with time. In stage II vein, early boiling occurred at 497$^{\circ}$C was succeeded by the occurrence of halite-bearing type III fluid inclusion with homogenization temperature as much as 100$^{\circ}$C lower. The salinities of type 1II fluid inclusion in stage II vein are 54.3 to 66.9 wt.% NaCI + KCI equiv. at 383$^{\circ}$ to 495$^{\circ}$C, indicating the formation depth less than 1 km. Type I cupriferous fluids in stage III vein have the homogenization temperatures and salinity of 168$^{\circ}$ to 365$^{\circ}$C and 1.1 to 9.0 wt.% NaCI equiv. These fluid inclusions in stage III veins were trapped in quartz veins containing highly fractured breccia, indicating the predominance of boiling evidence. This corresponds to hydrostatic pressure of 50 to 80 bars. The $\delta$$^{34}S$ value of sulfide minerals increase slightly with paragenetic time and yield calculated $\delta$$^{34}S_{H2S}$ values of 0.8 to 3.7$\textperthousand$. There is no mineralogical evidence that fugacity of oxygen decreased, and it is thought that the oxygen fugacity of the mineralizing fluids have been buffered through reaction with magnetite. We interpreted the range of the calculated $\delta$$^{34}S_{H2S}$ values for sulfides to represent the incorporation of sulfur from two sources into the Xiaoxinancha Cu-Au hydrothermal fluids: (1) an isotopically light source with a $\delta$$^{34}S$ value of I to 2$\textperthousand$, probably a Mesozoic granitoid related to the ore mineralization. We can infer from the fact that diorite as the host rock in the Xiaoxinancha Cu-Au deposit area intruded plagiogranite; (2) an isotopically heavier source with a $\delta$$^{34}S$ value of > 4.0$\textperthousand$, probably the local porphyry.