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Geochemical Study on the Naturally Originating Fluorine Distributed in the Area of Yongyudo and Sammokdo, Incheon
인천 용유도와 삼목도 지역 내 분포하는 자연기원 불소에 대한 지구화학적 연구
Econ. Environ. Geol. 2019 Aug;52(4):275-90
Published online August 31, 2019;  https://doi.org/10.9719/EEG.2019.52.4.275
Copyright © 2019 the Korean society of economic and environmental gelology.

Jong-Hwan Lee1, Jong-Ok Jeong2, Kun-Ki Kim3, Sang-Woo Lee1 and Soon-Oh Kim1*
이종환1 ·정종옥2 ·김건기3 ·이상우1 ·김순오1*

1Department of Geology and Research Institute of Natural Science (RINS), Gyeongsang National University (GNU), Jinju 52828, Republic of Korea
2Centralized Scientific Instrumentation Facility (CSIF), Gyeongsang National University(GNU), Jinju 52828, Republic of Korea
3Geochang Granite Research Center, Geochang 50103, Republic of Korea
1경상대학교 자연과학대학 지질과학과 및 기초과학연구소, 2경상대학교 공동실험실습관, 3(재)거창화강석연구센터
Received July 29, 2019; Revised August 27, 2019; Accepted August 28, 2019.
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 the original work is properly cited.
 Abstract
Geochemical study was conducted to elucidate the origin of fluorine (F) distributed in the rocks within the four areas of Yongyudo and Sammokdo, Incheon, which have been used as the source area of land reclamation for the 3rd and 4th stage construction sites of the Incheon International Airport. The main geology of the study area is Triassic biotite granite. Fluorine is contained at high levels in biotite granite, mylonite, and dykes (andesite and, basaltic-andesite). Furthermore, the higher concentrations of fluorine in the biotite granite can be contributed to fluorite. The results of microscopic analyses reveal that the fluorite was mostly observed as small vienlets together with quartz. This features support that fluorite was naturally formed due to the secondary process of hydrothermal fluids. In addition, fluorine was investigated to be highly enriched in a large amount of mica within the veins. In the case of mylonite, a high levels of fluorine was contributed to a large amount of sericite. The sericites contained in the mylointe, differently to those of the biotite granite, filled the micro-fractures of quartz formed as a result of mylonitization and included small cataclastic quartz grains. This indicates that fluorine was naturally enriched due to the alteration of hydrothermal fluids filling fractured zones formed by mylonitization. Consequently, the results of petrological and mineralogical study confirm that the fluorine distributed in the rocks within the Yongyudo and Sammokdo originated naturally.
Keywords : fluorine, natural origin, Yongjudo, Sammokdo, biotite granite, mylonite, fluorite, sericite

 

August 2019, 52 (4)