최승현 Seung Hyun Choi , 문향란 Hyang Ran Mun , 이영부 Young Boo Lee , 이정후 Jung Hoo Lee , 김영미 Young Mi Kim

DOI: Vol.25(No.1) 1-8, 2012

The metamorphic environments occrrred in the Sadong and the Gobangsan formations were studied through the investigation of chloritoid and white mica in shales at Munkyung area, two types of white mica occurs in the shale of Sadong formation; muscovite-dominant (Mu76.1Pa18.1Ma5.8) and margarite-dominant (Ma52.9Mu31.6Pa15.5). It is inferred that the muscovite-dominant white mica is generated by the diagenesis of Na-rich illite whereas the margarite-dominant white mica is generated by reactions between calcite and pyrophyllite separated from illite. In shales of the Gobangsan formation, chloritoids are observed with muscovite, pyrophyllite and chlorite. The chloritoids of the Gobangsan formation are considered to be originated from the reaction between pyrophyllite and chlorite. The Sadong and Gobangsan formations would have experienced the low-temperature metamorphism (anchizone) considering that white mica in general forms above the temperature of 200℃ and the assemblage of chloritoid-pyrophyllite-chlorite is stabilized below 280℃.

문경, 사동층, 고방산층, white mica, 클로리토이드, 파이로필라이트 Munkyung, Sadong formation, Gobangsan formation, white mica, chloritoid, pyrophyllite

박기남 Gi Nam Park , 황진연 Jin Yeon Hwang , 오지호 Ji Ho Oh , 이효민 Hyo Min Lee

DOI: Vol.25(No.1) 9-21, 2012

Six serpentine mines are found in South Korea. We investigated occurrence, characteristics and origin of constituent minerals of Bibong serpentine mine in Chungcheongnam-do. We also analyzed the properties of serpentine minerals using XRD, XRF, SEM/EDS, FT-IR, EPMA and polarized microscope. The serpentinite of Bibong mine occurs as intruded body within the Precambrian metasedi-mentary rocks. Various minerals such as serpentine, forsterite, pyroxene, tremolite, magnetite, chlorite, mica, talc and dolomite are occurre. Five distinctive mineral assemblage types are observed in the serpentinite: (A) serpentine-forsterite, (B) serpentine, (C) serpentine-chlorite (vermiculite), (D) serpentine-tremolite, (E) tremolite-chlorite. Lizardite and antigorite are mainly occurred as serpentine minerals and chrysotile is partly included. From the study of mineral compositions and occurrence of serpentinite body, serpentine formed by hydrothermal alteration of ultramafic rock consisting mainly of forsterite, and altered minerals such as chlorite and tremolite subsequently formed by secondary hydrothermal alteration.

사문석, 사문암, 투각섬석, 포스터라이트, 초염기성암, 열수변질작용, 크리소타일 serpentine, serpentinite, tremolite, forsterite, ultramafic rock, hydrothermal alteration, chrysotile

추창오 Chang Oh Choo , 장윤득 Yun Deuk Jang , 장천중 Chun Joong Chang

DOI: Vol.25(No.1) 23-36, 2012

Morphological and mineralogical characteristics of laumontite and adularia in the breccia zone in a fault, Yangbuk-myeon, Gyeongju, Korea suggest that they formed by reaction with hydrothermal alteration related to fault activity. Laumontite commonly occurring in the breccia zone is related to the presence of hydrothermal fluids bearing alkaline elements in the zone. Laumonite is characterized by elongated columnar form with aspect ratio varying 5∼10. Laumontite and adularia whose characteristic euhedral forms are indicative of the latest product formed as rapid precipitation from fluids or replacements of Ca-plagioclase. Hydrothermal fluids reacted with intensively fractured granite, typical with high permeability, leached alkaline elements such as Ca, K, allowing laumontite and adularia to be precipitated under neutral to weak alkaline conditions. It is noteworthy that the formation process and genesis of low temperature minerals such as laumontite and adularia are very similar to those formed by wallrock alteration or hydrothermal alteration that occurred in epithermal deposits, taking into account its characteristic morphology and chemistry, authigenic K-feldspar that commonly forms at low temperature in many fault zones must be adularia.

단층대, 각력암, 로몬타이트, 아듈라리아, 열수변질작용 fault zone, breccia, alumontite, adularia, hydrothermal alteration

최승현 Seung Hyun Choi , 이정후 Jung Hoo Lee

DOI: Vol.25(No.1) 37-40, 2012

류충렬 Chung Ryul Ryoo , 허철호 Chul Ho Heo , 미카엘발렌시아무노즈 Michael Valencia Munoz , 레이몬리베라코르네호 Raymond Rivera Cornejo , 알렉산더산띠스떼반안겔도니스 Alexander Santisteban Angeldonis

DOI: Vol.25(No.1) 41-50, 2012

이기재 Gill Jae Lee , 고상모 Sang Mo Koh

DOI: Vol.25(No.1) 51-61, 2012