Original Article

Econ. Environ. Geol. 2017; 50(3): 181-193

Published online June 30, 2017

https://doi.org/10.9719/EEG.2017.50.3.181

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

Mineralogy, Geochemistry, and Evolution of the Mn-Fe Phosphate Minerals within the Pegmatite in Cheolwon, Gyeonggi Massif

Gyoo Bo Kim1, Seon Gyu Choi1*, Jieun Seo1,2, Chang Seong Kim1, Jiwon Kim3 and Minho Koo3

1Department of Earth and Environmental Sciences, Korea University, Seoul 02841, Korea
2Department of Geology, Kyungpook National University, Daegu 41566, Korea
3Korea Resources Corporation, Wonju 26464, Korea

Correspondence to : seongyu@korea.ac.kr

Received: April 12, 2017; Revised: June 24, 2017; Accepted: June 26, 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

Mn-Fe phosphate mineral complexes included within the pegmatite are observed at Jurassic Cheolwon two-mica granite in Gyeonggi Massif, South Korea. The genetic evolution between the Cheolwon two-mica granite and pegmatite, and various trend of Mn-Fe phosphate minerals is made by later magmatic, hydrothermal, and weathering process based on mineralogical, geochemical analysis. The Cheolwon two-mica granite is identified as S-type granite, considering its chemical composition (metaluminous ~ peraluminous), post-collisional environment, low magnetic susceptibility, and existence of biotite and muscovite. The K-Ar age (ca. 153 Ma) of pegmatite is well coincident with age of the Cheolwon two-mica granite (151±4 Ma). It indicates that these two rocks are originated from the same magma. Pegmatite indicates the LCT geochemical signature, and was classified as muscovite-rare element class / Li subclass / beryl type / beryl-columbite-phosphate subtype pegmatite. The triplite {(Fe2+0.4,Mn1.6)(PO4)(F0.9)} is dominant phosphates in later magmatic stage which partly altered to leucophosphite {KFe3+2(PO4)2OH·2H2O} and jahnsite {(Fe3+0.7,Mn2.3)(PO4)2OH·4H2O} by hydrothermal alteration. In particular, near fractures, the triplite has been separatelty replaced by the phosphosiderite (Fe3+PO4·2H2O) and Mn-oxide minerals during weathering stage.

Keywords Pegmatite, phosphate mineral, triplite, leucophosphite, jahnsite, phosphosiderite

경기육괴 철원지역 페그마타이트 내 망간-철 인산염광물의 광물-지화학적 특징 및 진화과정

김규보1 ·최선규1* ·서지은1,2 ·김창성1 ·김지원3 ·구민호3

1고려대학교 지구환경과학과, 2경북대학교 지질학과, 3한국광물자원공사

요 약

Article

Original Article

Econ. Environ. Geol. 2017; 50(3): 181-193

Published online June 30, 2017 https://doi.org/10.9719/EEG.2017.50.3.181

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

Mineralogy, Geochemistry, and Evolution of the Mn-Fe Phosphate Minerals within the Pegmatite in Cheolwon, Gyeonggi Massif

Gyoo Bo Kim1, Seon Gyu Choi1*, Jieun Seo1,2, Chang Seong Kim1, Jiwon Kim3 and Minho Koo3

1Department of Earth and Environmental Sciences, Korea University, Seoul 02841, Korea
2Department of Geology, Kyungpook National University, Daegu 41566, Korea
3Korea Resources Corporation, Wonju 26464, Korea

Correspondence to:seongyu@korea.ac.kr

Received: April 12, 2017; Revised: June 24, 2017; Accepted: June 26, 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

Mn-Fe phosphate mineral complexes included within the pegmatite are observed at Jurassic Cheolwon two-mica granite in Gyeonggi Massif, South Korea. The genetic evolution between the Cheolwon two-mica granite and pegmatite, and various trend of Mn-Fe phosphate minerals is made by later magmatic, hydrothermal, and weathering process based on mineralogical, geochemical analysis. The Cheolwon two-mica granite is identified as S-type granite, considering its chemical composition (metaluminous ~ peraluminous), post-collisional environment, low magnetic susceptibility, and existence of biotite and muscovite. The K-Ar age (ca. 153 Ma) of pegmatite is well coincident with age of the Cheolwon two-mica granite (151±4 Ma). It indicates that these two rocks are originated from the same magma. Pegmatite indicates the LCT geochemical signature, and was classified as muscovite-rare element class / Li subclass / beryl type / beryl-columbite-phosphate subtype pegmatite. The triplite {(Fe2+0.4,Mn1.6)(PO4)(F0.9)} is dominant phosphates in later magmatic stage which partly altered to leucophosphite {KFe3+2(PO4)2OH·2H2O} and jahnsite {(Fe3+0.7,Mn2.3)(PO4)2OH·4H2O} by hydrothermal alteration. In particular, near fractures, the triplite has been separatelty replaced by the phosphosiderite (Fe3+PO4·2H2O) and Mn-oxide minerals during weathering stage.

Keywords Pegmatite, phosphate mineral, triplite, leucophosphite, jahnsite, phosphosiderite

경기육괴 철원지역 페그마타이트 내 망간-철 인산염광물의 광물-지화학적 특징 및 진화과정

김규보1 ·최선규1* ·서지은1,2 ·김창성1 ·김지원3 ·구민호3

1고려대학교 지구환경과학과, 2경북대학교 지질학과, 3한국광물자원공사

Received: April 12, 2017; Revised: June 24, 2017; Accepted: June 26, 2017

요 약

    KSEEG
    Jun 30, 2024 Vol.57 No.3, pp. 281~352

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