• Economic and Environmental Geology
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• v.33 no.5
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• pp.367-377
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• 2000

The purpose of this study is to elucidate the source of U anomaly formed in stream water of the drainage system around the Shinbo talc mine area based on the O, H, S and Sr isotopic characteristics of water masses and wall rocks. The ${\delta}$D and ${\delta}^{18}O$ of surface and ground waters show highly restricted range and plotted on the same meteoric water line, indicating that they are all originated from the meteoric water. The ${\delta}^{34}S$value of the ground water containing high U shows slightly negative (-0.2${\textperthousand}$) and quite distinct from those of the other surface and ground waters that are similar to those of wall rocks (>5.8${\textperthousand}$), indicating that they have a different S isotopic fractionation or less probably, source. The $^{87}Sr/^{86}{Sr}$ratios of water masses around the Shinbo talc mine area show a variable range from 0.724325 to 0.744928, but tend to increase with increasing U concentration of water mass. Although it is not possible to determine precisely the source rock of U anomaly formed in the hydrologic system around the Shinbo talc mine, the evidence obtained from the Sr isotopic compositions strongly suggests that coal schist and/or pegmatite vein could be the most likely candidate for the source rock.

• Economic and Environmental Geology
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• v.31 no.2
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• pp.101-110
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• 1998

The purpose of this study is to elucidate the source of U anormaly formed in stream water of the drainage system around the Shinbo talc mine area based on the hydrochemical properties of water masses including surface water and groundwater. The hydrochemical properties of water masses in the Shinbo talc mine area are divide into three types; Type I : $Ca(Mg)SO_4$ type with high U content as shown in the stream water flowout from the mine, Type II : $Ca(HCO_3)_2$ type with high U content as in deep groundwater, Type III : $Ca(HCO_3)_2$, type with low U content as in the other stream water and shallow groundwater. It is necessary to emphasize that in deducing the uranium source, a distinct discrimination between type I and type II is showed in their hydrothermal properties in spite of commonly having a high uranium content, which in turn means the occurrence of a different water-rock interaction processes between both type. All evidences suggest that type II groundwater have acted as a primary media in the transport of uranium and that, as the groundwater flows through the talc mineralization zone, water composition of type II was transformed into that of type I water as the results of a secondary water rock interaction process, caused by imposition of new mineralogically controlled thermodynamic constraints. Consequently, in the viewpoint of hydrochemical exploration, the investigation of the hydrologic circulation system and the hydrogeologic properties for the aquifer of type II groundwater shall be done first of all and will provide a crucial clue on tracing the uranium mineralization zone occurred in the Shinbo talc mine area.

• Economic and Environmental Geology
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• v.33 no.4
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• pp.261-271
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• 2000

In order to evaluate the environmental impact of U anormaly in the drainage system around the Shinbo talc mine area, U contents, their distribution patterns, bioaccumulation and a-radioactivity in stream water, stream sediments and aquatic organisms were investigated. The U contents of stream water attenuated with increasing distance from the mine area. The same attenuation pattern is shown in stream sediments from mine to 0.75 km downstream, although these contain highly enriched U contents (24~83 mg/kg) comparing with the international average concentration of surface soils (0.79~11 mg/kg). However, U content increases abruptly in sediment at 1.5 km downstream, probably due to detrital migration and rediposition of U enriched sediments. Futhermore, enriched U in downstream sediments occur in high proportions of carbonate and Fe-Mn oxide bounded forms, which show high potential of a secondary pollution source. For aquatic organisms, bio accumulation degree of U are in the order: aquatic larvae>black snail>mountain frog>crawfish. Cultured trout by the U enrich groundwater (387 ${\mu}g$/l) shows U accumulation in the part of branchia (CRs 5.25) and bones (CRs 11.2) but not in flesh (CRs 0.03). Total a-radioactivity have been measured in the level as 0.47 nCi/l for groundwater, 2.94~18 nCi/kg${\cdot}$DW for organisms and 93~328 nCi/kg${\cdot}$DW for sediments.

• Economic and Environmental Geology
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• v.45 no.1
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• pp.31-40
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• 2012

This paper examined the characteristics of ductile and brittle structural elements with detailed mapping by lithofacies classification to clarify the relationship between the geological structure and the geochemical high-grade uranium anormal zone and to provide the basic information on the flow of groundwater in the eastern area of Shinbo mine, Jinan-gun, Jeollabuk-do, Korea. It indicates that this area is mainly composed of Precambrian quartzite, metapelite, metapsammite, which show a zonal distribution of mainly ENE-WSW trend, and age unknown pegmatite and Cretaceous porphyry which intrude them. But the Cretaceous Jinan Group which unconformably covers them, contrary to assumption, could not be observed. The main ductile deformation structures of Precambrian metasedimentary rocks were formed at least through three phases of deformation [ENE striking regional foliation (D1) -> ENE or EW striking crenulation foliation (D2) -> WNW or EW trending open, tight, kink folds (D3)]. The predominant orientation of S1 regional foliation strikes ENE and dips south, being similar to the zonal distribution of Precambrian metasedimentary rocks. Most predominant orientation of high-angled brittle fracture (dip angle ${\geq}45^{\circ}$) [ENE (frequency: 24.3%) > NS (23.9%) > (N)NW (18.8%) > WNW (16.9%) > NE (16.1%) fracture sets in descending frequency order], which is closely related to the flow of groundwater, strikes ENE and dips south. It also agrees with the zonal distribution of metasedimentary rocks and the predominant orientation of S1 regional foliation. The next one strikes NS and dips east or west. Considering the controlling factor of the geochemical uranium anormal zone in the Shinbo mine and its eastern areas from the above structural data. the uranium source rock in these areas might be pegmatite and the geochemical uranium anormal zone in the Sinbo mine area could be formed by an secondary enrichment through the flow of pegmatite aquifer's groundwater into the Sinbo mine area like the previous research's result.

• Economic and Environmental Geology
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• v.45 no.4
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• pp.385-396
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• 2012

The geochemical high-grade uranium anormal zone has been reported in the Shinbo mine and its eastern areas, Jinan-gun, Jeollabuk-do located in the southwestern part of Ogcheon metamorphic zone, Korea. In this paper is reported the time-relationship between deformation and growth of metamorphic minerals in the eastern area of Shinbo mine, which consists of the Precambrian metasedimentary rocks (quartzite, metapelite, metapsammite) and the age-unknown pegmatite and Cretaceous porphyry which intrude them, and is considered the relative mineralization time on the basis of the previous research's result. The D1 deformation formed the straight-type Si internal foliation which is defined mainly as the arrangement of elongate quartz, biotite, opaque mineral in andalusite porphyroblast. The D2 deformation, which is defined by the microfolding of Si foliation, formed S2 crenulation cleavage. It can be divided into two sub-phases, early crenulation and late crenulation. The former occurs as the curvetype Si foliation in the mantle part of andalusite. The latter occurs as S1-2 composite foliation which warps around the andalusite. The andalusite porphyroblast began to grow under non-deformation condition after the formation of S1 foliation which corresponds to the straight-type Si foliation. It continued to grow before the late crenulation phase. The age-unknown pegmatite intruded after the D2 deformation and grew the fibrous sillimanite which random masks the S1-2 composite foliation. The D3 deformation formed F3 fold which folded the S1-2 composite foliation, D2 crenulation, fibrous sillimanite. It means that the intrusion of pegmatite related to the growth of the fibrous sillimanite took place during the inter-tectonic phase of D2 and D3 deformations. The retrograde metamorphism is recognized by the chloritization of biotite and two-way cleavage lamellae which is parallel to the S1-2 composite foliation and the F3 fold axial surface in the andalusite porphyroblast. It occurred during the D2 late crenulation phase and D3 deformation. In considering of the previous research's result inferring the most likely candidate for the uranium source rock as pegamatite, it indicates that the age-unknown pegmatite intruded during the inter-tectonic phase of D2 and D3 deformations, i.e. during the retrograde metamorphism related to the uplifting of crust, and formed the uranium ore zone around the Shinbo mine.