Constraints on the structure and composition of the active layer are important for understanding permafrost evolution. Soil convection owing to repeated moisture-induced freeze-thaw cycles within the active layer promotes the formation of self-organized patterned ground. Here we present the results of ground penetrating radar (GPR) surveys across a selected sorted circle near King Sejong Station, Antarctica, to better delineate the active layer and its relation to the observed patterned ground structure. We acquire GPR data in both bistatic mode (common mid-points) for precise velocity constraints and monostatic mode (common-offset) for subsurface imaging. Reflections are derived from the active layer-permafrost boundary, organic layer-weathered soil boundary within the active layer, and frozen rock-fracture-filled ice boundary within the permafrost. The base of the imaged sorted circle possesses a convex-down shape in the central silty zone, which is typical for the pattern associated with convection-like soil motion within the active layer. The boundary between the central fine-silty domain and coarse-grained stone border is effectively identified in a radar amplitude contour at the assumed active layer depth, and is further examined in the frequency spectra of the near- and far-offset traces. The far-offset traces and the traces from the lower frequency components dominant on the far-offset traces would be associated with rapid absorption of higher frequency radiowave due to the voids in gravel-rich zone. The presented correlation strategies for analyzing very shallow, thin-layered GPR reflection data can potentially be applied to the various types of patterned ground, particularly for acquiring time-lapse imaging, when electric resistivity tomography is incorporated into the analysis.

본 연구에서는 제주 서귀포지역에서 산출되는 온천수 2지점과 탄산수 2지점에 대한 화학성분, CFCs (Chlorofluorocarbons) 동위원소, <TEX>${\delta}^{18}O$</TEX>, <TEX>${\delta}D$</TEX>, <TEX>${\delta}^{13}C$</TEX> 동위원소, 영족기체(He, Ne) 동위원소 분석을 통하여 탄산온천수와 탄산수의 수리화학적 특성, 생성연령, 영족기체의 기원과 <TEX>$CO_2$</TEX> 가스의 기원을 해석하였다. 연구지역의 탄산수의 pH는 6.21~6.84의 범위의 약산성과 매우 높은 전기전도도 값(<TEX>$1,928{\sim}4,720{\mu}S/cm$</TEX>)의 특성을 보인다. 화학적 유형은 <TEX>$Mg(Ca,Na)-HCO_3$</TEX> 내지는 <TEX>$Na(Ca,Mg)-HCO_3$</TEX> 유형을 보인다. 환경추적자인 CFCs 농도를 이용하여 지하수 연령측정결과, 탄산수는 약 47.5~57.2년, 지하수는 약 30.3~49.5년으로 추정되었다. 탄산수의 <TEX>${\delta}^{13}C$</TEX>값은 -1.77~-7.27‰의 범위를 보여 <TEX>$CO_2$</TEX> 가스의 기원은 심부기원과 일부 심부-무기기원의 혼합 기원으로 도시되었지만, 영족기체 조성비(<TEX>$^3He/^4He$</TEX>, <TEX>$^4He/^{20}Ne$</TEX>)에서 헬륨가스가 심부기원의 농도가 절대적으로 높은 값을 보여 화산활동과 관련한 심부 마그마 기원임을 보여준다. In this study, geochemical composition, CFCs (Chlorofluorocarbons), <TEX>${\delta}^{18}O$</TEX>, <TEX>${\delta}D$</TEX>, <TEX>${\delta}^{13}C$</TEX> isotopes and noble gases isotopes (He, Ne) were analyzed to determine their recharge age, source of <TEX>$CO_2$</TEX> gas and noble gases of carbonated hot spring water and carbonated-water samples collected in the Seoqwipo of the Jeju. The pH of the carbonated waters ranges from 6.21 to 6.84, and the high electrical conductivity range (<TEX>$1,928{\sim}4,720{\mu}S/cm$</TEX>). Their chemical composition is classified as <TEX>$Mg(Ca,\;Na)-HCO_3$</TEX> and <TEX>$Na(Ca,\;Mg)-HCO_3$</TEX> types. As a result of the calculation of groundwater age using CFCs concentrations as an environmental tracer, the carbonated water and groundwater were estimated to be about 47.5~57.2 years and about 30.3~49.5 years, respectively. The <TEX>${\delta}^{13}C$</TEX> values of carbonated water range from -1.77 to -7.27‰, and are plotted on thr deep-seated field or the mixing field of the deep-seated and inorganic origin. Noble gases isotopic (<TEX>$^3He/^4He$</TEX>, <TEX>$^4He/^{20}Ne$</TEX>) ratio shows that helium gas of carbonated hot waters comes from deep-seated magma origin.

한반도 동남부에 발달된 양산단층과 감포지역 단층대에서 지하수의 순환에 대한 단층대의 영향을 알아보기 위하여 10개 암반 지하수를 채취하여 화학성분과 영족기체 동위원소 특성을 분석하였다. 분석결과 지하수의 화학적 유형은 <TEX>$Ca-HCO_3$</TEX> 형에서 <TEX>$Ca-SO_4(Cl)$</TEX> 형의 영역을 보이며, 지질과의 뚜렷한 상관성을 보이지 않는다. 영족기체인 <TEX>$^3He/^4He$</TEX>와 <TEX>$4^He/^{20}Ne$</TEX> 동위원소비 상관관계도에서 1점을 제외한 지하수는 대기기원의 <TEX>$^3He$</TEX>가 우세하며, 이는 단층대를 통하여 강수의 지하수로 유입이 활발한 대수층 환경임을 지시한다. 아울러 단층대를 통한 심부의 헬륨공급이 없는 환경임을 시사한다. <TEX>$^4He$</TEX>의 비율이 비교적 높은 지하수는 물-암석반응이 상대적으로 충분한 대수층조건에서 암석기원의 <TEX>$^4He$</TEX>가 일부 기원되었음을 지시한다. The chemical composition and noble gas isotopes of 10 deep groundwater samples were analyzed to know the circulation of groundwaters in the Yangsan fault and the Gampo fault. The chemical types of groundwaters show the <TEX>$Ca-HCO_3$</TEX> type and <TEX>$Ca-SO_4(Cl)$</TEX> type, and show indistinct relationship with geology. Noble gas isotopic data of most groundwaters were plotted along the air-crust mixing line on <TEX>$^3He/^4He$</TEX> vs. <TEX>$4^He/^{20}Ne$</TEX> diagram, and show dominant <TEX>$^3He$</TEX> of air origin except one sample that shows helium mixing of crust origin. This indicates that groundwater actively circulates along fault, and fault could not play an role of upward pathway of a deep-seated helium gas. A comparatively high <TEX>$^4He$</TEX> indicates that groundwater flows in an aquifer assuring relatively enough water-rock interaction.