• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.470-475
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• 2003

KIGAM (Korea Institute of Geoscience and Mineral Resources) launched a new project to develop the low-enthalpy geothermal water in the area showing high geothermal anomaly, north of Pohang city, for large-scale space heating from KORP (Korea Research Council of Public Science & Technology) funding. Surface geologic and geophysical surveys including Landsat TM image analysis, gravity, magnetic, Magnetotelluric (MT) and controlled-source audio-frequency MT (CSAMT) and self-potential (SP) methods have been conducted and the possible fracture zone was found that would serve as deeply connected geothermal water conduit. By the end of 2003, two test wells of 1 km depth will be drilled and various kinds of borehole survey along with additional MT measurements and sample analysis will follow and then the detailed subsurface condition is to be characterized. Next step would be drilling the production well of 2 km depth and all further steps remain to be determined depending upon the results of the test well studies.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.2
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• pp.59-65
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• 1999

Both the groundwater changes due to different pumping rates and the geochemistry of thermal waters in the Suanbo area are considered in this study. The observation of groundwater level change since 1991 shows that the change is directly correlated with pumping rates of thermal waters and reveals the retardation of ca. 5 weeks after pumping. The hydrogeological aquifer in the area is under reducing condition. The thermal waters are of Na-HCO$_3$ type. and are alkaline (pH=8.5∼8.7) with low TDS values (274∼284 mg/l) and high concentrations of Na (68∼72 mg/l). F (6.4∼8.9 mg/l), and HCO$_3$(136∼146 mg/l). Oxygen and hydrogen isotope ratios of thermal water indicate a meteoric water origin. The activities of Rn-222 and Ra-226 in both thermal water and local groundwater were determined to delineate possible geochemical controls on the Rn-222 and Ra-226. The Rn-222 concentrations are several orders of magnitude greater than the Ra-226 concentrations. The concentrations of Rn-222 range from 190 to 7.490 pCi/1 with an average of 2,522 pCil/l. and those of Ra-226 average 0.32 pCi/1 with the range from 0.25 to 0.42 pCi/1. The concentrations of Rn-222 and Ra-226 are inversely correlated with EC and alkalinity. The pH it positively correlated with Ra-226. The correlation between Rn-222 and Ra-226 is poor. Thermal waters in the study area are produced from highly fractured phyllite. The thermal water qualify. CSAMT (controled-source audiofrequency magnetotelluric) prospecting, and petrological evidences, however, indicate that the heat is possibly transmitted through deep normal faults reaching a deep granite batholith, and the phyllite acts only as a groundwater pathway.

• Economic and Environmental Geology
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• v.44 no.4
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• pp.313-320
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• 2011

The Taebaegsan Mineralized District is the most prospective region for the useful mineral commodities such as a coal, non-metallic, metallic mineral in South Korea. From a general point of view, Cambro- Ordovician limestone formations, Myobong slate and Pungchon (Daegi) limestone, are the most fertilizable formations in the Taebaegsan Mineralized District. The geology around Weondong mine area consists mainly of Carboniferous-Triassic formations and Cambro-Ordovician formations intruded by rhyolite/quartz porphyry. The great overthrusted fault of N40~$50^{\circ}E$ direction, so called Weondong overthrust fault, is observed in the central part of the mine area and the NS fault system cuts the overthrusted fault. By postulating from the favorable geological and structural condition around Weondong area, the possibility of deep seated hidden ore bodies is expected. In 2010, on the basis of the results of LOTEM and CSAMT survey, the cross-hole survey was performed for the investigation of the hidden polymetallic ore body in the deep parts of the Weondong mine area and the grade of the newly-discovered orebody is as follows; (1) The cut-off grade for lead-zinc 3%; an weighted average grade 5.50% (2.7 m), (2) The cutoff grade for copper 0.1%; an weighted average grade 0.91% (14.65 m), (3) The cut-off grade for iron 30%; an weighted average grade 38.18% (3.3 m), (4) $WO_3$ for each cut-off grade(0.01%, 0.05%, 0.1%); an weighted average grade 0.29 wt. % (8.8 m), 1.15 wt. % (2.1 m), 1.97 wt. % (1.2 m), (5) $MoS_2$ for each cut-off grade(0.01%, 0.1%); an weighted average grade 0.15 wt. % (6.3S m), 0.28 wt. % (3.15 m), (6) $Ta_2O_5$ for each cut-off grade (0.01%, 0.1%); an weighted average grade 0.13% (19.S m), 1.11% (1.8 m), (7) $Nb_2O_5$ for each cut-offgrade (0.01%, 0.1%); an weighted average grade 0.06% 11.5 m), 0.15% (3.0 m).