• Economic and Environmental Geology
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• v.20 no.1
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• pp.35-60
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• 1987

The geochemical characteristics including minerals, major and trace elements chemistries of the Proterozoic, Jurassic and Cretaceous granites in Korea are systematically summarized and intended to decipher the origin and crystallization process in connection with the tectonic evolution. The granites in Korea are classified into three different ages of the granites with their own distinctive geochemical patterns: 1) Proterozoic granitoids; 2) Jurassic granites(cratonic and mobile belt); 3) Cretaceous-Tertiary granites. The Proterozoic granite gneisses (I-type and ilmenite-series) formed by metamorphism of the geochemically evolved granite protolith. The Proterozoic granites (S-type and ilmenite-series) produced by remobilization of sialic crust. The Jurassic granites (S-type and ilmenite-series) were mainly formed by partial melting of crustal materials, possibly metasedimentary rocks. The Cretaceous granites (I-type and magnetite-series) formed by fractional crystallization of parental magmas from the igneous protolith in the lower crust or upper mantle. The low temperature ($315{\sim}430^{\circ}C$) and small temperature variations (${\pm}20{\sim}30^{\circ}C$) in the cessation of exsolution of perthites for the Proterozoic and Jurassic granites might have been caused by slow cooling of the granites under regional metamorphic regime. The high ($520^{\circ}C$) and large temperature variations (${\pm}110^{\circ}C$) of perthites for the Cretaceous granites postulate that the rapid cooling of the granitic magma. In terms of the oxygen fugacity during the feldspar crystallization in the granite magmas, the Jurassic mobile belt granites were crystallized in the lowest oxygen fugacity condition among the Korean granites, whereas the Cretaceous granites in the Gyeongsang basin at the high oxygen fugacity condition. The Jurassic mobile belt granites are located at the Ogcheon Fold Belt, resulting by closing-collision situation such as compressional tectonic setting, and emplaced into a Kata-Mesozonal ductile crust. The Jurassic cratonic granites might be more evolved either during intrusion through thick crust or owing to lower degree of partial melting in comparison with the mobile belt granites. The Cretaceous granites are possibly comparable with a continental margin of Andinotype. Subduction of the Kula-Pacific ridge provided sufficient heat and water to trigger remelting at various subcrustal and lower crustal igneous protoliths.

• Journal of the Korean earth science society
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• v.22 no.4
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• pp.278-291
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• 2001

Mesothermal gold vein minerals of the Seolhwa mine were deposited in a single stage of massive quartz veins which filled the mainly NE-trending fault shear zones exclusively in the granitoid of the Gyeonggi Massif. The Seolhwa mesothermal gold mineralization is spatially associated with the Jurassic granitoid of 161 Ma. The vein quartz contains three main types of fluid inclusions at 25$^{\circ}$C: 1) low-salinity (< 5 wt.% NaCl), liquid CO$_{2}$-bearing, type IV inclusion; 2) gas-rich (> 70 vol.%), aqueous type II inclusions; 3) aqueous type I inclusions (0${\sim}$15 wt.% NaCl) containing small amounts of CO$_{2}$. The H$_{2}$O-CO$_{2}-CH$_{4}$-N$_{2}$-NaCl inclusions represent immiscible fluids trapped earlier along the solvurs curve at temperatures from 430$^{\circ}$ to 250$^{\circ}$C and pressures of 1 kbars. Detailed fluid inclusion chronologies may suggest a progressive decrease in pressure during the auriferous mineralization. The aqueous inclusion fluids represent either later fluids evelved through extensive fluid unmixing (CO$_{2}-CH$_{4}$ effervescence) from a homogeneous H$_{2}$O-CO$_{2}-CH$_{4}$-N$_{2}$-NaCl fluid due to decreases in temperature and pressure, or the influence of deep circulated meteoric waters possibly related to uplift and unloading of the mineralizing suites. The initial fluids were homogeneous containing H$_{2}$O-CO$_{2}-CH$_{4}$-N$_{2}$-NaCl components and the following properties: the initital temperature of >250$^{\circ}$ to 430$^{\circ}$C, X$_{CO}\;_{2}$ of 0.16 to 0.62, 5 to 14 mole% CH$_{4}$, 0.06 to 0.3 mole% N$_{2}$ and salinities of 0.4 to 4.9 wt.% NaCl. The T-X data for the Seolhwa gold mine may suggest that the Seolhwa auriferous hydrothermal system has been probably originated from adjacent granitic melt which facilitated the CH$_{4}$ formation and resulted in a reduced fluid state evidenced by the predominance of pyrrhotite. The dominance of negative ${\delta}\;^{34}$S values of sulfides (-0.6 to 1.4$%_o$o) are consistent with their deep igneous source.

• Economic and Environmental Geology
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• v.56 no.3
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• pp.343-363
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• 2023

Sulawesi island, as a global producer of nickel resources, is leading the rapid growth of nickel industry of Indonesia. Nickel laterite deposits in Sulawesi was formed by lateritization of the world-scale East Sulawesi Ophiolite (ESO) under the active tectonic setting and tropical rainforest climate. In this paper, exploration cases for nickel laterite deposits in five regions of Sulawesi are reported. Regional characteristics on nickel laterite deposits in Sulawesi are understood based on various exploration activities such as outcrop, trench and pit survey, petrological observation, geochemical analysis, and interpretation of drilling data, etc.. In the northeastern part of 'Southeast-Arm', which is a strategic location for nickel industry of Indonesia, ESO is extensively exposed to the surface. In the Morombo and Morowali regions, typical high-grade saprolite-type orebodies with a thickness of 10 to 20 m occur. The cases showed that topographic relief tends to regulate Ni-grade distribution and orebody thickness, and that high grade intervals tend to occur in places where joints and garnierite veins are dense. In the Tinanggea and South Palangga regions in the southern part of the Southeast-Arm, overburden composed of Neogene to Quaternary deposits is a major factor affecting the preservation and profitability of nickel laterite deposits. Despite the overburden, high-grade saprolite-type orebodies composed of Ni-bearing serpentine with garnierite veins occur in a thickness of around 10 m to secure economic feasibility. In contrast, in the Ampana region in the northern part of 'East-Arm', low-grade nickel laterite deposits with immature laterite profile was identified, which is thought to be the result of active denudation due to tectonic uplift. Exploration cases in this paper will help to understand characteristics and controlling factors on nickel laterite deposits in Sulawesi, Indonesia.

• Pediatric Infection and Vaccine
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• v.11 no.1
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• pp.81-89
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• 2004

Purpose : Retropharyngeal and parapharyngeal abscesses are often distinguishable from other head and neck abscesses on clinical grounds, but these infections can combine and the presentations are similar to one another. Because of the advances of antibiotic therapy, the frequency of the diseases decreased considerably, but recently the incidence of neck abscesses has increased. We sought to describe the clinical presentation of patients with deep neck abscess, and implications on management. Methods : For 10 year periods, 94 cases of charts were reviewed retrospectively, who were diagnosed as neck abscesses aged below 16 years old(between January 1993 to August 2003) in 4 hospitals. Deep neck abscesses were diagnosed by surgical pus drainage, neck CT (homogenous, hypodense area with ring enhancement) and neck sono findings. Results : The annual incidence of deep neck abscess has been increased since 2000. The median age of the patients was 4 years(range, 26 days~15 years); 63% of the patients were younger than 5 years. Abscesses in the submandibular space(34%) were most common, followed by peritonsillar space(29.7%), retropharyngeal space(11.7%), combined(10.8%), parotid space(7.4%) and parapharyngeal space(6.4%). Fever(73.4%), sore throat(37.2%), decreased oral intake(34%) and neck pain(27.7%) were the most common symptoms. In 6 children(6.4%), there was refusal to move neck, in 6(6.4%) headache, and in 4(4.3%) torticollis. Respiratory distress was observed in only 1 patient(2.1%) and stridor in 1 other(2.1%). The most common physical examinations were neck swelling/mass(67%), pharyngitis(46.8%), tonsillitis(36.2 %), and cervical lymphadenopathy(28.7%). Neck stiffness was observed in 4 patients(4.3%). Total 35 organisms were isolated in 33 patients. The most common organisms cultured by patients' blood or pus were S. aureus(34%) and S. pyogenes(28.6%). Most organisms were gram positive, and had sensitivities in vancomycin(96.4%), cefotaxime(88.9%), cephalothin (86.4%), trimethoprime-sulfamethoxazole(83.3%), and clindamycin(77.8%). 77 patients(81.9%) underwent surgery plus antibiotics; 17 patients(18.1%) were treated with antibiotics only. There is no significant differences between two groups. In duration of admission, fever after admission, and antibiotic treatment. Conclusion : The incidence of deep neck abscess has increased recently and the major symptoms have been changed. The incidence of respiratory distress or stridor is decreasing, while the incidence of abnormal head and neck symptoms and signs like headache, neck stiffness, refusal to move neck, or torticollis are increasing. Gram positive organisms are predominant, S. aureus is the most common followed by S. pyogenes. 1st generation cephalosporin has high sensitivity on gram positive organisms. Treatment with surgery plus antibiotics dose not significantly decrease total duration of antibiotic treatment or admission compared to treatment with antibiotics alone.