• Economic and Environmental Geology
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• v.40 no.5
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• pp.675-689
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• 2007

Kilauea volcano's summit area was formed by continuous ind/or sporadic eruption activities for several hundreds years. In this study, we mainly focused on the trace elements characteristics through systematic sample rocks erupted from 1790 to September of 1982. Under the microscope it can be observed some main minerals such as olivine, clinopyroxene. and plagioclase with minor opaque minerals including Cr-spinel and ilmenite. Zr, V, Y, Ti elements show incompatible activities with MgO while Ni, Cr, Co elements show highly compatible properties. Elements like as Ba, Rb, Th, Sr, Nd are highly incompatible to show positive trends with $K_2O$. In the REE diagram LREE is more enriched than HREE suggesting typical Oceanic Island Basalt(OIB) type. It can be suggested that Sr have an effect on the fractionation of plagioclase from the kink in the $K_2O$ variation diagram. Y/Ho ratio diagram shows there was no fluids effect in the historical Kilauea volcano but Zr/Hf ratio diagram shows a significant difference between Kilauea lavas and PuuOo lavas. There are distinctive changes of trace element contents showing in particular abrupt changes of temporal variations between 1924 and 1954. Moreover, PuuOo lavas which had been erupted since 1983 follow these decreasing trends of trace element variation. Therefore, it is strongly suggested that these abrupt changes of trace elements trends result from the huge collapse geological event which formed Halemaumau crater in 1924 causing contamination effects of crustal contents into magma chamber and from the changes of parental magma composition injected into Kilauea volcano's summit magma reservoir.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.20 no.1
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• pp.49-59
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• 1984

Optimizing investigation of characteristics of underwater welding by a gravity type arc welding process was experimentally carried out by using six types of domestic coated welding electrodes for welding of domestic marine structural steel plates (KR Grade A-1, SWS41A, SWS41B,) in order to develop the underwater welding techniques in practical use. Main results obtained are summarized as follows: 1. The absorption speed of the coating of domestic coated lime titania type welding-electrode became constant at about 60 minutes in water and it was about 0.18%/min during initial 8 minutes of absorption time. 2. Thus, the immediate welding electrode could be used in underwater welding for such a short time in comparison with the joint strength of in-atmosphere-and on-water-welding by dry-, wet-or immediate-welding-electrode. 3. By bead appearance and X-ray inspection, ilmenite, limetitania and high titanium oxide types of electrodes were found better for underwater-welding of 10 mm KR Grade A-1 steel plates, while proper welding angle, current and electrode diameter were 6$0^{\circ}C$, above 160A and 4mm respectively under 28cm/min of welding speed. 4. The weld metal tensile strength or proof stress of underwater-welded-joints has a quadratic relationship with the heat input, and the optimal heat input zone is about 13 to 15KJ/cm for 10mm SWS41A steel plates, resulting from consideration upon both joint efficiency of above-100% and recovery of impact strength and strain. Meanwhile, the optimal heat input zone resulting from tension-tension fatigue limit above the base metal's of SWS41A plates is 16 to 19KJ/cm. Reliability of all the empirical equations reveals 95% confidence level. 6. The microstructure of the underwater welds of SES41A welded in such a zone has no weld defects such as hydrogen brittleness with supreme high hardness, since the HAZ-bond boundary area adjacent to both surface and base metal has only Hv400 max with the microstructure of fine martensite, bainite, pearlite and small amount of ferrite.

• The Journal of the Petrological Society of Korea
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• v.19 no.1
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• pp.31-49
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• 2010

Nearly NS-trending Fe-Ti ore bodies intermittently occur in the Hadong anorthosites, south Korea, irrespective of the rock types of the anorthosites. In order to determine their occurrence mode and deformation history, we collected the features of occurrence and geological structures in the field, petrographic features using thin sections of the principal constituent rocks, and geochemical data of ilmenites in the ore body using electron probe microanalysis. Fe-Ti ore bodies examined in this study are divided into two types: dike- and lamina-types. It is steadily supported that the dike-type has intruded into the anorthositic rocks after their emplacement and solidification. And the laminar-type is probably a result of the mylonitization and transposition of the dike-type ore bodies parallel to the shear planes, due to later strong dextral ductile shearing. In the meantime, the Fe-Ti ore bodies have experienced the stronger dextral shearing in the more northern part of the study area, i.e. Cheongryong-ri, Wolhoeng-ri, Jonghwa-ri, and Jayangri and Baekun-ri in ascending order of its strength, together with the less content of $TiO_2$. All ilmenites of the ore bodies have very similar chemical composition, as pure ilmenite of 52~55 wt.% in $TiO_2$ content, irrespective of the occurrence mode and degree of later ductile shearing of the ore bodies. And they didn't experience to exsolve into magnetite. The structural data indicate that the Hadong anorthosites have deformed by NNE-trending folding, intrusion of the Fe-Ti ore bodies, NNW~NNE-trending dextral ductile shearing, NW~NNW-trending sinistral semi-brittle shearing, and intrusion of NNE~NE-trending mafic dykes in descending order of chronology after the formation of foliation of the anorthositic rocks. The foliation is interpreted as a result of the accumulation of crystals that settle out from the magma by the action of gravity.

• The Journal of the Petrological Society of Korea
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• v.10 no.1
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• pp.27-35
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• 2001

The charnockite of Jirisan area occurs within the Precambrian high grade metamorphic terrane associated with anorthosite body as many foreign examples. Sm-Nd ages were determined from whole rock-garnet pairs, which turned out $1827\pm$32($2\sigma$) Ma for the massive charnockite and $1820\pm$22(2$\sigma$) Ma for the foliated charnockite with $$\varepsilon$_{Nd}(T)$ of $-5.5\pm$0.2 and $-6.0\pm$0.5 respectively. $^{87}Sr/^{86}Sr$ initial ratios calculated with the these ages are 0.71319 and 0.71532 respectively. The fact that massive and foliated charnockites show identical age, identical Nd isotopic initial ratio, and similar Sr isotopic initial ratios suggest that they were generated at the same time from the same material even through their present textures are different. Initial ratios of Nd and Sr of the charnockites are quite distinct from the mantle values indicating the influence of continental crust. Sm-Nd age determined from the titanium bearing anorthositic rocks intruding the anorthosite body, using mineral separates of garnet, plagioclase, and mafic fraction, is $1792\pm$90(2$\sigma$) Ma with $$\varepsilon$_{Nd}(T)=-3.9$\pm$0.2$. The ^${87}Sr/^{86}Sr$ initial ratios calculated with this age are 0.70616~0.70619. The charnockites and the anorthositic rocks occurring in contact each other also reveal the same age within the error, which suggest a genetic relationship between them. However, chemical compositions of the charnockites and Hadong-Sancheong anorthosites cannot be explained by igneous differentiation. Their differences in Nd and Sr initial isotopic ratios indicate different source materials. Therefore, temporal association between them suggests the possibility of the anorthosite acting as a thermal source for the generation of the charnockite as other studies.

• Journal of the Mineralogical Society of Korea
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• v.32 no.3
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• pp.223-234
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• 2019

The geology of the Samdeok Mo deposit consists of Paleozoic Hwajeonri formation, Kowoonri formation, Suchangri formation, Iwonri formation, Hwanggangri formation, Cretaceous, leucocratic porphyritic granite and granitic porphyry. This deposit consists of three quartz veins that filled NS oriented fractured zones in Suchangri formation. Quartz veins vary from 0.05 m to 0.3 m in thickness and extend to about 400 m in strike length. Quartz veins occur as massive, breccia, and cavity textures. Wallrock alteration has silicification, sericitization, argillitization and chloritization. The mineralogy of the quartz veins consists of quartz, fluorite, white mica, biotite, apatite, monazite, rutile, ilmenite, molybdenite, chalcopyrite, Fe-Mg-Mn oxide and Fe oxide. White mica from Samdeok Mo deposit occurs as fine or coarse grains in quartz vein and hostrock and has four mineral assemblages (I type: quartz, molybdenite, Fe oxide and Fe-Mg-Mn oxide, II type: quartz, Fe oxide and Fe-Mg-Mn oxide, III type: quartz and biotite, and IV type: quartz). The structural formular of white mica from quartz vein is $(K_{0.89-0.60}Na_{0.05-0.00}Ca_{0.01-0.00}Sr_{0.02-0.00})_{0.94-0.62}(Al_{1.54-1.12}Mg_{0.36-0.18}Fe_{0.26-0.09}Mn_{0.04-0.00}Ti_{0.02-0.00}Cr_{0.02-0.00}Zn_{0.01-0.00})_{1.91-1.72}(Si_{3.40-3.11}Al_{0.92-0.60})_{4.00}O_{10}(OH_{1.68-1.42}F_{0.58-0.32})_{2.00}$, but white mica of I type has higher FeO content, and lower $SiO_2$ and MgO contents than white micas of other types. Also, compositional variations in white mica from the Samdeok Mo deposit are caused by phengitic or Tschermark substitution ($(Al^{3+})^{VI}+(Al^{3+})^{IV}{\leftrightarrow}(Fe^{2+}{\text{ or }}Mg^{2+})^{VI}+(Si^{4+})^{IV}$) and direct $(Fe^{3+})^{VI}{\leftrightarrow}(Al^{3+})^{VI}$ substitution.

• Journal of the Mineralogical Society of Korea
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• v.32 no.2
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• pp.127-143
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• 2019

The geology of the Chulmasan area consists of Precambrain Sogeunri formation, granitic gneiss, foliated biotite granite, foliated mica granite, basic dyke and acidic dyke. REE mineralization in the area occurs at granitic gneiss and foliated mica granite. Minerals with minor amounts of REE and Th from granitic gneiss and foliated mica granite are zircon ($Y_2O_3$ 0.00~1.18 wt.%, $Gd_2O_3$ 0.00~0.59 wt.%, $Er_2O_3$ 0.00~0.22 wt.%, $Yb_2O_3$ 0.00~0.34 wt.%, $Lu_2O_3$ 0.00~0.48 wt.%, $ThO_2$ 0.00~0.33 wt.%), thorianite ($Nd_2O_3$ 0.00~0.24 wt.%, $Lu_2O_3$ 0.00~0.26 wt.%), berthierine ($La_2O_3$ 0.04~0.26 wt.%, $Nd_2O_3$ 0.00~0.20 wt.%, $Tb_2O_3$ 0.04~0.12 wt.%, $Dy_2O_3$ 0.17~0.26 wt.%, $Er_2O_3$ 0.33~0.44 wt.%, $Lu_2O_3$ 0.00~0.19 wt.%, $ThO_2$ 0.61~0.93 wt.%), chlorite ($La_2O_3$ 0.44~0.68 wt.%, $Ce_2O_3$ 0.12~0.13 wt.%, $Nd_2O_3$ 0.31~0.44 wt.%, $Eu_2O_3$ 0.03~0.08 wt.%, $Dy_2O_3$ 0.09~0.21 wt.%, $Ho_2O_3$ 0.04~0.14 wt.%, $Er_2O_3$ 0.18~0.32 wt.%, $Lu_2O_3$ 0.07~0.21 wt.%, $ThO_2$ 0.00~0.97 wt.%), biotite ($Nd_2O_3$ 0.02~0.08 wt.%, $Gd_2O_3$ 0.07~0.08 wt.%, $Tb_2O_3$ 0.02~0.07 wt.%, $Dy_2O_3$ 0.35~0.43 wt.%, $Ho_2O_3$ 0.15~0.26 wt.%, $Er_2O_3$ 0.24~0.28 wt.%, $Yb_2O_3$ 0.06~0.18 wt.%, $ThO_2$ 0.00~0.12 wt.%), orthoclase ($Dy_2O_3$ 0.05~0.12 wt.%, $Ho_2O_3$ 0.05~0.06 wt.%, $Er_2O_3$ 0.28 wt.%, $Yb_2O_3$ 0.06~0.12 wt.%) and plagioclase ($Ho_2O_3$ 0.01~0.03 wt.%, $Er_2O_3$ 0.10~0.27 wt.%, $ThO_2$ 0.11~0.13 wt.%). REE minerals (bastnaesite and fergusonite) were sealed fractures in mainly fledspar, mica, zircon, apatite and ilmenite. Therefore, bastnaesite and fergusonite from the Chulmasan area were formed from redissolution/reconcentration of REE-and Th-bearing minerals from granitic gneiss and foliated mica granite at late stage by several igneous activies and metamorphism.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.4
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• pp.273-288
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• 2023

The Gubong Au-Ag deposit, which has been one of the largest deposits (Unsan, Daeyudong, Kwangyang) in Korea, consists of eight lens-shaped quartz veins (a mix of orogenic-type and intrusion-related types) that filled fractures along fault zones within Precambrian metasedimentary rock. Korea Mining Promotion Corporation found a quartz vein (referred to as the No. 6 vein with a grade of 27.9 g/t Au and a width of 0.9 m) at a depth of -728 ML by drilling (No. 90-12) conducted in 1989. Korea Mining Promotion Corporation conducted drilling (No. 04-1) in 2004 to investigate the redevelopment's possibility of the No. 6 vein. The author studied the occurrence and chemical composition of chlorite and white mica using wallrock, wallrock alteration and quartz vein samples collected from the No. 04-1 drilling core in 2004. The alteration of studied samples occurs chloritization, sericitization, silicification and pyritization. Chlorite and white mica from mineralized zone at a depth of -275 ML occur with quartz, K-feldspar, calcite, rutile and pyrite in wallrock alteration zone and quartz vein. Chlorite and white mica from ore vein (No. 6 vein) at a depth of -779 ML occur with quartz, calcite, apatite, zircon, rutile, ilmenite, pyrrhotite and pyrite in wallrock alteration zone and quartz vein. Chlorite from a depth of -779 ML has a higher content of Al and Mg elements and a lower content of Si and Fe elements than chlorite from a depth of -275 ML. Also, Chlorites from a depth of -275 ML and -779 ML have higher content of Si element than theoretical chlorite. Compositional variation in chlorite from a depth of -275 ML was mainly caused by phengitic or Tschermark substitution [Al^{3+,VI + Al3+,IV} <-> (Fe²⁺ or Mg²⁺)^VI + (Si⁴⁺)^IV], but compositional variation from a depth of -779 ML was mainly caused by octahedral Fe²⁺ <-> Mg²⁺ (Mn²⁺) substitution. The interlayer cation site occupancy (K+Na+Ca+Ba+Sr = 0.76~0.82 apfu, 0.72~0.91 apfu) of white mica from a depth of -275 ML and -779 ML have lower contents than theoretical dioctahedral micas, but octahedral site occupancy (Fe+Mg+Mn+Ti+Cr+V+Ni = 2.09~2.13 apfu, 2.06~2.14 apfu) have higher contents than theoretical dioctahedral micas. Compositional variation in white mica from a depth of -275 ML was caused by phengitic or Tschermark substitution [(Al³⁺)^VI + (Al³⁺)^IV <-> (Fe²⁺ or Mg²⁺)^VI + (Si⁴⁺)^IV], illitic substitution and direct (Fe³⁺)^VI <-> (Al³⁺)^VI substitution. But, compositional variation in white mica from a depth of -779 ML was caused by phengitic or Tschermark substitution [(Al³⁺)^VI + (Al³⁺)^IV <-> (Fe²⁺ or Mg²⁺)^VI + (Si⁴⁺)^IV] and direct (Fe³⁺)^VI <-> (Al³⁺)^VI substitution.