중원 지역 탄산수의 지구화학적 진화

• 발행기관: 대한자원환경지질학회
• 저자명: 고용권 윤성택 김천수 최현수 김건영
• 간행물 정보: 『자원환경지질』32권 5호, 469~483쪽, 전체 15쪽
• 주제분류: 자연과학 > 지질학
• 파일형태: PDF
• 발행일자: 1999.10.30

영문 초록

Two different types of deep groundwaters occur together in the Jungwon area: CO2-rich water and alkali water. Each water shows distrinct hydrogeochemical and environmental isotopic characteristics. The Co2-rich waters are characterized by lower pH(6.0∼6.4), higher Eh (25∼85mV) and higher TDS content (up to 3,300 mg/l), whereas the alkali type waters have higher pH (9.1∼9.5), lower Eh (-136∼-128mV) and lower TDS content (168∼254 mg/l). The CO2-rich waters (Pco2=up to 1atm) were probably evolved by the local supply of deep CO2 during the deep circulation, resulting in enhanced dissolution of surrounding rocks to yield high concentrations of Ca2+, Na+, Mg2+, K+ and HCO3- under low pH conditions. On the other hand, the alkali type waters (Pco2=about 10-4.6 atm) were evolved through lesser degrees of simple wate/rock (granite) interaction under the limited suppy of CO2. The alkali waters are relatively enriched in F- (up to 14mg/l), whereas the F- concentration of CO2-rich water is lower (2.2∼4.8 mg/l) due to the buffering by precipitation of fluorite. The oxygen-hydrogen isotopes and tritium data indicate that compared to shaltion (δ18O=-9.5∼-7.8‰),two different types fo deep groudwaters (<1.0TU)were both derived from pre-thermonuclear (more than 40 years old) meteoric waters with lighter O-H isotopic composition (δ18O=-10.5∼-9.48‰) and have evolved through prolonged water/rock interaction. The CO2-rich waters also show some degrees of isotopic re-equilibration with CO2 gas. The δ18S values of dissolved sulfates (+24.2∼+27.6‰) in the CO2-rich waters suggest the reduction of sulfate by organic activity at depths. The carbon isotope data show that dissolved carbon in the CO2-rich waters were possibly derived either from dissolution of calcite or from deep CO2 gas. However, strontium isotope data indicate Ca in the CO2-rich waters were derived mainly from plagioclase in granite, not from hydrothermal calcites.

키워드

충북 중원군 능암리 대화광산 황화광물 열수 W-Mo 광상 회중석 지구화학적 진화