• Economic and Environmental Geology
• /
• v.35 no.6
• /
• pp.553-565
• /
• 2002

Seasonal variations in vertical distributions of metals were investigated in the contaminated paddy soils around Siheung Cu-Pb-Zn and Deokeum Au-Ag mines. Geochemical behavior of metals was also evaluated with respect to redox changes during the cultivation of rice. Two microcosms simulating the rice-growing paddy field were set up in the laboratory. The raw paddy soils from two sites showed differences in mineralogy, metal concentrations and gecochemical parameters, and it is suggested that high proportions of exchangeable fractions in metals may give high dissolution rates at Deokeum. In both microcosms of Siheung and Deokeum, redox differences between surface and subsurface of paddy soils were maintained during the flooded period of 18 weeks. Siheung soil had neutral to alkaline pH conditions, while strongly acidic conditions and high Eh values were found at the surface soil of Deokeum. The concentrations of dissolved Fe and Mn were higher in the subsurface pore waters than in interface and upper waters from both microcosms, indicating reductive dissolution under reducing conditions. On the contrary, dissolved Pb and Zn had high concentrations at the surface under oxidizing conditions. From the Siheung microcosm, release of dissolved metals into upper waters was decreased. presumably by the trap effect of Fe- and Mn-rich layers at the interface. However, in the Deokeum microcosm, significant amounts of Pb and Zn were released into upper water despite the relatively lower contents in raw paddy soil, and seasonal variations in the chemical fractionation of metals were observed between flooded and drained conditions. Under acidic conditions, rice may uptake high amounts of metals from the surface of paddy soils during the flooded periods, and increases of exchangeable phases may also increase the bioavailability of heavy metals in the drained conditions.

• Economic and Environmental Geology
• /
• v.45 no.2
• /
• pp.89-104
• /
• 2012

The solubility of aluminum for two Andisol profiles formed on pyroclastic materials and basaltic rocks from Jeju Island, Korea was investigated. It is found that high organic carbon content and $Al_{pyrophosphate}/Al_{oxalate}$ ratios in the A horizons, suggesting the substantial amounts of reactive Al are associated with organic matter, whereas the low organic carbon content and the $Al_{pyrophosphate}/Al_{oxalate}$ ratios in the Bo horizons indicate that a major part of the reactive Al should be bound inorganically. The differential FT-IR spectra following acid-oxalate dissolution and heating up to 150 and $350^{\circ}C$, and transmission electron microscope (TEM) observation confirm that imogolite is in the Bo horizon. Our results of equilibration experiments demonstrate that the Al solubility in the Bo horizon for Andisols can be clarified by the congruent dissolution model for imogolite-type material (ITM), rather than by the simultaneous equilibrium with both ITM and Al hydroxy-interlayered aluminosilicate. With results from dialysis and aging procedures, it is noted that the formation of a proto imogolite sol showing its transformation to imogolite, which supports the congruent dissolution of ITM primarily controlling the Al solubility of Andisols in Jeju Island, Korea.

• Economic and Environmental Geology
• /
• v.45 no.2
• /
• pp.79-88
• /
• 2012

The increased brightness and focused X-ray beams now available from laboratory X-ray sources facilitates a variety of powder diffraction experiments not practical using conventional in-house sources. Furthermore, the increased availability of 2-dimensional area detectors, along with implementation of improved software and customized sample environmental cells, makes possible new classes of in-situ and time-resolved diffraction experiments. These include phase transitions under variable pressure- and temperature conditions and ion-exchange reactions. Examples of in-situ and time-resolved studies which are presented here include: (1) time-resolved data to evaluate the kinetics and mechanism of ion exchange in mineral natrolite; (2) in-situ dehydration and thermal expansion behaviors of ion-exchanged natrolite; and (3) observations of the phases forming under controlled hydrostatic pressure conditions in ion-exchanged natrolite. Both the quantity and quality of the in-situ diffraction data are such to allow evaluation of the reaction pathway and Rietveld analysis on selected dataset. These laboratory-based in-situ studies will increase the predictability of the follow-up experiments at more specialized beamlines at the synchrotron.

• Economic and Environmental Geology
• /
• v.43 no.5
• /
• pp.429-441
• /
• 2010

The Sunrise Dam gold deposit is located approximately 850 km ENE of Perth, in the eastern part of the Yilgam Craton, Western Australia. The mine has produced approximately 153 t of Au at an average grade of 4.2 g/t, which stands for the most significant gold discoveries during the last decade in Western Australia. The deposit occurs in the Laverton Tectonic Zone corresponding to the corridor of structural complexity in the Laverton greenstone belt, and characterized by tight folding and thrusting. The mine stratigraphy consists of a complexly deformed and altered volcaniclastic and volcanic rocks. These have been overlain by a turbidite sequence containing generally well-sorted siltstones, sandstones and magnetite-rich shales, which are consistently fining upwards. These sequences have been intruded by quartz diorite, ultramafic dikes, and rhyodacite porphyry (Archean), and lamprophyre dikes (Palaeoproterozoic). These rocks constitute the asymmetric NNE-trending Spartan anticline with north-plunging thrust duplication of the BIF unit. The deposit is located on the western limb of this structure. Transported, fluvial-lacustrine and aeolean sediments lie unconformably over the deposit showing significant variation in relief. Gold mineralization occurs intermittently along a NE-trending corridor of ca. 4.5 km length. The 20 currently defined orebodies are centered on a series of parallel, gently-dipping ($\sim30^{\circ}$) and NESW trending shear zones with a thrust-duplex architecture and high-strain characteristics. The paragenetic sequence of the Sunrise Dam deposit can be divided into five hydrothermal stages ($D_1$, $D_2$, $D_3$, $D_4a$, $D_4b$), which are supported by distinctive features of the mineralogical assemblages. Among them, the D4a stage is the dominant episode of Au deposition, followed by the $D_4b$ stage, which is characterized by more diverse ore mineralogy including base metal sulfides, sulfosalts, and telluride minerals. The $D_4a$ stage contains higher proportions of microscopic free gold (48%) than D4b stage (12%), and pyrite is the principal host for native gold (electrum) followed by tetrahedrite-group minerals in both stages.

• Economic and Environmental Geology
• /
• v.46 no.3
• /
• pp.267-278
• /
• 2013

The East African Rift System(EARS) is known to be hosted epithermal Au-Ag deposits, and the best-known example is Main Ethiopian Rift Valley(MER) related to Quaternary bimodal volcanism. Large horst-graben system during rifting provides open space for emplacement of bimodal magmas and flow channel of geothermal fluids. In recent, large hydrothermally altered zones(Shala, Langano, and Allalobeda) and hot spring related to deeply circulating geothermal water have been increasing their importance due to new discoveries in MER and Danakil depression. The hot springs in Shala and Allalobeda occur as boiling pool and geyser on the surface, whereas some areas didn't observe them due to decreasing ground water table. The host rocks are altered to quartz, kaolinite, illite, smectite, and chlorite due to interaction with rising geothermal water. The hot springs in MER are neutral to slightly alkaline pH(7.88~8.83) and mostly classified into $HCO_3{^-}$ type geothermal water. They are strongly depleted in Au, and Ag, but show a higher Se concentration of up to 26.7 ppm. In contrast, siliceous altered rocks around hot springs are strongly enriched in Pb(up to 33 ppm, Shala), Zn(up to 313 ppm, Shala), Cu(up to 53.1 ppm, Demaegona), and Mn(up to 0.18 wt%t, Shala). In conclusion, anomalous Se in hot spring water, Pb, Zn, Cu, and Mn in siliceous altered rocks, and new discoveries in MER have been increasing potential for epithermal gold mineralization.

• Economic and Environmental Geology
• /
• v.51 no.5
• /
• pp.439-453
• /
• 2018

The Eocene Gyeongju granitoids in SE Korea are alkali feldspar granite (AGR), biotite granite (BTGR), and hornblende biotite granodiorite (HBGD) along Yangsan fault and Ulsan fault. According to their geochemical characteristics, these granitoids are classified as A-type (AGR) and I-type (BTGR and HBGD) granitoids, and regarded that were derived from same parental magma in upper mantle. The hornblende and biotite of AGR as an interstitial phase indicate that influx of F-rich fluid during the crystallization of AGR magma. AGR is enriched LILE (except Sr and Ba) and LREE that indicate the influences for subduction released fluids. The highest HFSE contents and zircon saturation temperature of AGR among the Eocene Gyeongju granitoids may indicate that it was affected by partial melting rather than magma fractionation. These characteristics may represent that the high F contents of AGR was affected by F-rich fluid derived from the subducted slab and partial melting. It corresponds with the results of the REE modeling and the dehydrated fluid component (Ba/Th) modeling showing that AGR (A-type) was formed by the partial melting of BTGR (I-type) with the continual influx of F-rich fluid derived from the subducted slab.

• Korean Journal of Poultry Science
• /
• v.24 no.4
• /
• pp.193-198
• /
• 1997

This study was conducted to obtain the basic information for hatchery by-products as feed resources. Four kinds of by-products from a commercial hatchery, i. e., autoclaved day-old broiler or egg type chicks, dead embryos ＆ infertile eggs of both chicks were used for chemical composition and bioavailability test. Chemical compositions were obtained by AOAC (1990) method, and amino acid and energy bioavailabilities were determined by the method of Sibbald (1976). The crude protein contents of day-old chicks (60.27∼62.59) were higher than those of dead embryos ＆ infertile eggs (39.24∼40.09) , whereas the crude fat contents of all by-products were not different. The crude ash contents were higher in dead embryos ＆ infertile eggs (29.18∼34.49％) than in day-old chicks (6.50∼6.71％). The Ca contents of dead embryos ＆ infertile eggs (8.79∼10.82％) were higher than those of day-old chicks (1.29∼l.30％). The total amino acid contents, overall amino acid availabilities and ME contents were higher in day-old chicks than in dead embryos ＆ infertile eggs. It seems that the day-old chicks of egg strain can be used as a high protein - high energy feed resources and the dead embryos ＆ infertile eggs of broiler or egg type as a high protein-high calcium feed ingredients.

• Resources Recycling
• /
• v.21 no.4
• /
• pp.44-52
• /
• 2012

The purpose of this study is to confirm the possibility of obtaining high grade coal from fixed carbon 20.68% coal. Also, the mineralogical, physical/chemical and liberation characteristics was found with the aim of decrease in ash amount, during the pre-processing of clean coal technology. In this study, batch flotation and microbubble column flotation that was appropriate for the processing of fine particles was used with the variation in kinds and quantity of frother, collector and depressant. Also grinding time, air flow rate and feeding rates were examined. As a result of batch flotation, using pulp density 20%, collector DMU-101+dodecyl amine(100 mL/ton), frother pine oil (200 mL/ton), depressant sodium silicate(1 kg/ton), obtained the result of ash rejection 81.55% and combustible recovery 70.23%. In result of microbubble column flotation, the result was ash rejection 83.85% and combustible recovery 70.42% under the condition of pulp density 5%, grinding time 5 min. collector DMU-101+DDA(100 mL/ton), frother AF65(5.4 L/ton), depressant SMP(3.5 kg/ton), wash water(360 mL/min.) and air flow rate(1,197 mL/min.).

• Economic and Environmental Geology
• /
• v.39 no.6 s.181
• /
• pp.663-674
• /
• 2006

It is very important that analysis of textures in rock, the moving of hydrothermal solution along the structures, epithermal vein textures, mineralization and composition minerals to confirm the hydrothermal ore deposits and ore genesis. The purpose of this study is to confirm the gold mineralization and ore genesis through the moving of hydrothermal solution along the structure lines and epithermal vein textures by using Color-corescanner techniques. The three drilling hole cores of Sunshin Gold Mine in Haenam area in Jeonnam Province were into a digital image data. Digital image data of gold bearing epithermal vein textures were analyzed detaily by Color-corescanner. There are several epithermal vein textures, namely Comb texture, Cavity texture, Bladed texture, Zonal texture, Brecciated texture and Combined texture. Gold mineralization is dominated in vein type textures, but high grade gold are enbedded in brecciated texture. Ore genesis is epithermal gold deposit. This Color-corescanner techniques can cover the missing part of the examine with the naked eye, and can examine closely the situation of ore deposit development and genesis by detail checking the textures in rock, mineralization and so on.

• Economic and Environmental Geology
• /
• v.45 no.6
• /
• pp.623-641
• /
• 2012

The Janggun lead-zinc-silver deposit is hydrothermal-metasomatic deposit. We have sampled wallrock, hydrother-maly-altered rock and lead-zinc-silver ore vein to study the element dispersion during wallrock alteration. The hydrothermal alteration that is remarkably recognized at this deposit consists of rhodochrositization and dolomitization. Wallrock is dolomite and limestone that consisit of calcite, dolomite, quartz, phlogopite and biotite. Rhodochrosite zone occurs near lead-zinc-silver ore vein and include mainly rhodochrosite with amounts of calcite, dolomite, kutnahorite, arsenopyrite, pyrite, chalcopyrite, sphalerite, galena and stannite. Dolomite zone occurs far from lead-zinc-silver ore vein and is composed of mainly dolomite and minor calcite, rhodochrosite, pyrite, sphalerite, chalcopyrite, galena and stannite. The correlation coefficients among major, trace and rare earth elements during wallrock alteration show high positive correlations(dolomite and limestone = $Fe_2O_3(T)$/MnO, Ga/MnO and Rb/MnO), high negative correlations(dolomite = MgO/MnO, CaO/MnO, $CO_2$/MnO, Sr/MnO; limestone = CaO/MnO, Sr/MnO). Remarkable gain elements during wallrock alteration are $Fe_2O_3(T)$, MnO, As, Au, Cd, Cu, Ga, Pb, Rb, Sb, Sc, Sn and Zn. Remarkable loss elements are CaO, $CO_2$, MgO and Sr. Therefore, elements(CaO, $CO_2$, $Fe_2O_3(T)$, MgO, MnO, Ga, Pb, Rb, Sb, Sn, Sr and Zn) represent a potential tools for exploration in hydrothermal-metasomatic lead-zinc-silver deposits.