Original Article

Econ. Environ. Geol. 2017; 50(6): 445-466

Published online December 31, 2017

https://doi.org/10.9719/EEG.2017.50.6.445

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

Hydrogeochemistry of Groundwater Occurring in Complex Geological Environment of Yeongdong Area, Chungbuk, Korea

Sang-Ho Moon*

Geologic Environment Division, Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon 34132, Korea

Correspondence to : msh@kigam.re.kr

Received: December 11, 2017; Revised: December 27, 2017; Accepted: December 28, 2017

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided original work is properly cited.

Abstract

Yeongdong area is located in the contact zone between central southeastern Ogcheon belt and Yeongnam massif, in which Cretaceous Yeongdong basin exists. Therefore, the study area has complex geological environment of various geological age and rock types such as Precambrian metamorphic rocks, age-unknown Ogcheon Supergroup, Paleozoic/Mesozoic sedimentary rocks, Mesozoic igneous rocks and Quaternary alluvial deposits. This study focuses on the link between the various geology and water type, and discussed the source of some major ions and their related water-rock interaction. For this study, the field parameters and ion concentrations for twenty alluvial/weathered and eighty bedrock aquifer wells were used. Statistical analysis indicates that there was no significant differences in groundwater quality between wet and dry seasons. Although various types were observed due to complex geology, 80 to 84 % of samples showed Ca-HCO3 water type. Some wells placed in alluvial/weathered aquifers of Precambrian metamorphic and Jurassic granitic terrains showed somewhat elevated NO3 and Cl concentrations. Mg-HCO3 typed waters prevailed in Cretaceous Yeongdong sedimentary rocks. The deeper wells placed in bedrock aquifers showed complicated water types varying from Ca-HCO3 through Ca-Cl/SO4/NO3 to Na- HCO3 and Na-Cl type. Groundwater samples with Na-HCO3 or Na-Cl types are generally high in F concentrations, indicating more influences of water-rock interaction within mineralized/hydrothermal alteration zone by Cretaceous porphyry or granites. This study revealed that many deep-seated aquifer had been contaminated by NO3, especially prominent in Jurassic granites area. Based on molar ratios of HCO3/Ca, HCO3/Na, Na/Si, it can be inferred that Ca and HCO3 components of most groundwater in alluvial/weathered aquifer wells were definitely related with dissolution of calcite. On the other hand, Ca and HCO3 in bedrock aquifer seem to be due to dissolution of feldspar besides calcite. However, these molar ratios require other mechanism except simple weathering process causing feldspar to be broken into kaolinite. The origin of HCO3 of some groundwater occurring in Cretaceous Yeongdong sedimentary rock area seems to be from dissolution of dolomite(MgCO3) or strontianite(SrCO3) as well.

Keywords Yeongdong area, complex geology, groundwater, water-rock interaction, calcite dissolution, feldspar weathering

충북 영동군 복합 지질지역에서 산출되는 지하수의 수리지화학적 특성

문상호*

한국지질자원연구원 지질환경연구본부 지하수생태연구센터

요 약

Article

Original Article

Econ. Environ. Geol. 2017; 50(6): 445-466

Published online December 31, 2017 https://doi.org/10.9719/EEG.2017.50.6.445

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

Hydrogeochemistry of Groundwater Occurring in Complex Geological Environment of Yeongdong Area, Chungbuk, Korea

Sang-Ho Moon*

Geologic Environment Division, Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon 34132, Korea

Correspondence to:msh@kigam.re.kr

Received: December 11, 2017; Revised: December 27, 2017; Accepted: December 28, 2017

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided original work is properly cited.

Abstract

Yeongdong area is located in the contact zone between central southeastern Ogcheon belt and Yeongnam massif, in which Cretaceous Yeongdong basin exists. Therefore, the study area has complex geological environment of various geological age and rock types such as Precambrian metamorphic rocks, age-unknown Ogcheon Supergroup, Paleozoic/Mesozoic sedimentary rocks, Mesozoic igneous rocks and Quaternary alluvial deposits. This study focuses on the link between the various geology and water type, and discussed the source of some major ions and their related water-rock interaction. For this study, the field parameters and ion concentrations for twenty alluvial/weathered and eighty bedrock aquifer wells were used. Statistical analysis indicates that there was no significant differences in groundwater quality between wet and dry seasons. Although various types were observed due to complex geology, 80 to 84 % of samples showed Ca-HCO3 water type. Some wells placed in alluvial/weathered aquifers of Precambrian metamorphic and Jurassic granitic terrains showed somewhat elevated NO3 and Cl concentrations. Mg-HCO3 typed waters prevailed in Cretaceous Yeongdong sedimentary rocks. The deeper wells placed in bedrock aquifers showed complicated water types varying from Ca-HCO3 through Ca-Cl/SO4/NO3 to Na- HCO3 and Na-Cl type. Groundwater samples with Na-HCO3 or Na-Cl types are generally high in F concentrations, indicating more influences of water-rock interaction within mineralized/hydrothermal alteration zone by Cretaceous porphyry or granites. This study revealed that many deep-seated aquifer had been contaminated by NO3, especially prominent in Jurassic granites area. Based on molar ratios of HCO3/Ca, HCO3/Na, Na/Si, it can be inferred that Ca and HCO3 components of most groundwater in alluvial/weathered aquifer wells were definitely related with dissolution of calcite. On the other hand, Ca and HCO3 in bedrock aquifer seem to be due to dissolution of feldspar besides calcite. However, these molar ratios require other mechanism except simple weathering process causing feldspar to be broken into kaolinite. The origin of HCO3 of some groundwater occurring in Cretaceous Yeongdong sedimentary rock area seems to be from dissolution of dolomite(MgCO3) or strontianite(SrCO3) as well.

Keywords Yeongdong area, complex geology, groundwater, water-rock interaction, calcite dissolution, feldspar weathering

충북 영동군 복합 지질지역에서 산출되는 지하수의 수리지화학적 특성

문상호*

한국지질자원연구원 지질환경연구본부 지하수생태연구센터

Received: December 11, 2017; Revised: December 27, 2017; Accepted: December 28, 2017

요 약

    KSEEG
    Oct 30, 2023 Vol.56 No.5, pp. 501~628

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