Physical, Mechanical and Durability Properties of the Quartzite Units of Central Nepal Lesser Himalaya

( Dinesh Raj Sharma ),( Naresh Kazi Tamrakar ),( Upendra Baral ) 대한지질공학회 2024 지질공학 Vol.34 No.1

This study compares the quartzites of four quartzite units: The Fagfog Quartzite, Dunga Quartzite (member of the Robang Formation), Pandrang Quartzite (member of the Kalitar Formation) and the Chisapani Quartzite. The analysis shows variations in flakiness and elongation, as the Fagfog Quartzite displays low flakiness whereas the Pandrang and the Chisapani have moderate and the Dunga Quartzite has shown variations. The density values of the four quartzite units remain consistent, indicating uniform physical properties and porosity levels. However, bulk density values differ among the quartzites, suggesting variations in particle arrangement, porosity, and density. Regarding strength measures, the Pandrang and the Chisapani Quartzite have higher strength characteristics as compared to the Fagfog and the Dunga Quartzites. The Pandrang Quartzite has the highest average point load strength index, classifying it as “Extremely Strong”. The resistance to impact and crushing forces varies among the quartzites, with lower Aggregate Impact Value (AIV) and Aggregate Crushing Value (ACV) indicating higher strength and durability. Durability tests show that the Fagfog Quartzite has high durability against slaking, with a slight decrease observed after the fifth cycle. The Dunga Quartzite shows varying degrees of weathering, while the Pandrang and the Chisapani Quartzite have minimal weight changes, indicating strong resistance to weathering. Magnesium sulfate soundness tests indicate high durability and resistance to degradation for all four units. The Los Angeles abrasion value (LAAV) tests indicate favorable resistance to abrasion for the majority of the Fagfog, Dunga, and the Pandrang Quartzites samples, while Chisapani Quartzite shows more variability in LAAV values. The Pandrang Quartzite shows a higher proportion of elongated particles but lower flakiness index values as compared to Fagfog and Dunga Quartzites while Chisapani Quartzite stands out with a significantly higher presence of flaky particles and lower elongation index values. Mechanically, the Fagfog and Dunga Quartzite show higher strength and better resistance to abrasion and freeze and thaw. The Pandrang Quartzite shows moderate resistance to crushing and sudden effect, while the Chisapani Quartzite has variable resistance to effect. This comparative study emphasizes the diversity and complexity of quartzite rock types, showing the need for comprehensive characterization and assessment to determine their suitability for specific applications.

규석 종류에 따른 ALC 물성 연구

추용식(Chu, Yong-Sik),서성관(Seo, Sung-Kwan),임두혁(Im, Du-Hyuk),송훈(Song, Hun),이종규(Lee, Jong-Kyu),이승호(Lee, Seung-Ho) 한국건설순환자원학회 2011 한국건설순환자원학회지 Vol.6 No.4

본 연구에서는 ALC의 물리적 특성에 영향을 줄 수 있는 다양한 인자 중 규석 종류를 검토하였으며, 이때 회수슬러리를 재활용하였다. 규석은 문경 및 금평 규석을 사용하였으며, 규석 분말 입수분도 실험하였다. 규석의 XRD 분석과 광물상 분석을 통해 문경 규석의 주요 광물은 석영과 운모로, 금평 규석은 석영으로 구성되어 있음을 확인하였다. 더불어 금평 규석에 존재하는 석영의 결정성이 좀 더 양호하다는 것도 알 수 있었다. ALC의 밀도와 기공특성은 규석별 차이가 관찰되지 않았으나, 압축강도 및 A-수는 문경 규석보다 금평 규석 사용시에 양호한 특성을 발현하였다. 이러한 현상은 규석에 존재하는 주요 광물 결정종의 차이, 석영입자 결정성 및 미량성분 함량 차이 등의 영향으로 추정되었다. ALC was fabricated using cement, lime and quartzite by hydrothermal reaction. The kind of quartzite was reviewed for ALC properties and returned slurry was recycled in this study. Munkyung and Kumpyung quartzite was used and quartzite powder was experimented. The major mineral phase of Munkyung quartzite was quartz and muscovite crystal but that of Kumpyung was quartz. It was certain that crystallinity of Kumpyung quartzite was superior to Munkyung quartzite. Compressive strength and A-number of ALC with Kumpyung quartzite was higher than that of ALC with Munkyung quartzite under similar specific gravity. These results was resulted from major mineral phase, crystallinity and minor components of quartzite.

X-선 형광분석기를 이용한 덕용 규암의 주원소 분석 및 표준물질 활용 검토

조현지,김고은,양윤석,한인규,최은철,정봉근,김명정,조희제 한국분석과학회 2024 분석과학 Vol.37 No.6

이번 연구에서는 규석‧규사 분석용 표준물질(reference material)로의 활용 가능성을 확인하고자파장분산형 X-선 형광분석기를 이용하여 국내 덕용 광산에서 채취한 규암을 대상으로 주원소 분석을 수행하였다. 미분쇄한 덕용 규암 시료(DK)의 균질성을 평가하기 위해 실험실 간 교차분석과 반복측정(n = 160)을 수행하였다. 그리고 2002년도에 제작된 덕용 규석 표준물질(KSi-2)을 분석하여 시간 경과에따른 조성 변화를 평가하였다. DK 시료의 측정값은 기보고된 KSi-2 시료의 측정값과 오차범위 내 일치하며, 장기간 보관된 KSi-2 시료의 재분석 결과는 기보고된 값과 오차범위 내 일치해 시료의 높은 안정성이 확인되었다. 이번 연구와 기보고된 덕용 규암 시료(DK + KSi-2)의 주원소 및 강열감량의 측정 결과는SiO2, 98.39 ± 0.15 wt.%; Al2O3, 0.70 ± 0.01 wt.%; Fe2O3, 0.24 ± 0.01 wt.%; CaO, 0.014 ± 0.005 wt.%; MgO, 0.03± 0.01 wt.%; K2O, 0.16 ± 0.01 wt.%; Na2O, 0.02 ± 0.01 wt.%; TiO2, 0.039 ± 0.001 wt.%; P2O5, 0.011 ± 0.002 wt.%; LOI, 0.34 ± 0.09 wt.%이며, 측정값의 오차는 ± 0.2 % 이내로 덕용 규암의 주원소 조성은균질한 것으로 판단된다. 이번 지화학 연구를 통해 덕용 규암 시료는 천연 지질 표준물질로의 사용이적합하다고 판단되며, 규석‧규사의 시험 분야에서 활용 가치가 높을 것으로 예상된다 In this study, the concentrations of major to trace elements in Duckyong quartzite, South Korea, were measured using wavelength-dispersive X-ray fluorescence to evaluate its potential as a reference material for silica stones and silica sands. To assess the homogeneity of the Duckyong quartzite (DK), the inter-laboratory comparisons and repeated analyses (n = 160) were conducted on powdered samples. Additionally, the newly produced glass disk samples of Duckyong quartzite (KSi-2), previously produced in 2002, were reanalyzed to monitor possible change in composition over time. The measured values of DK samples were consistent with those of KSi-2 samples within uncertainties. The analytical results of re-evaluated KSi-2, which had been stored for an extended period, were consistent with previously reported values within uncertainties, reflecting the high stability of Duckyong quartzite samples. The measured nine major elements and loss on ignition (LOI) of the Duckyong quartzite samples (DK + KSi-2) in new and previously studies were as follows: SiO2, 98.39 ± 0.15 wt.%; Al2O3, 0.70 ± 0.01 wt.%; Fe2O3, 0.24 ± 0.01 wt.%; CaO, 0.014 ± 0.005 wt.%; MgO, 0.03 ± 0.01 wt.%; K2O, 0.16 ± 0.01 wt.%; Na2O, 0.02 ± 0.01 wt.%; TiO2, 0.039 ± 0.001 wt.%; P2O5, 0.011 ± 0.002 wt.%; and LOI, 0.34 ± 0.09 wt.%. The uncertainties of the measured values were within ± 0.2 %, indicating the homogeneity of Duckyong quartzite. This geochemical study indicates that the Duckyong quartzite, with high homogeneity and stability, is suitable as a natural geological reference material. It is anticipated to be utilized extensively in the testing field for silica-stone and silica-sand analyses.

한국 구석기시대 석영계 석재의 기계적 성질 비교 시론 - 임진-한탄강 유역을 중심으로

유용욱 한국구석기학회 2012 한국구석기학보 Vol.- No.25

Majority of researchers agrees that the crudeness of lithic tools is influenced by the coarseness and mechanical poorness of locally available raw material. In particular, the quartz and quartzite are main candidates to inevitably produce simple tools and have been entitled poor quality raw material category. However, we do not have any solid evidence to support that these two rocks are really “hard-to-deal” resource. In order to furnish a reliable background to classify excellent and poor quality raw material, a comparison of mechanical properties between so-called “high-quality” raw material—flint and chert—and quartz/quartzite rocks from the Imjin-Hantan River Area, Korea was made. The flint and chert were obtained from well-known classic palaeolithic sites of Europe: St. Acheul and the vicinity of the Somme River, Les Eyzies and the vicinity of the Vezere River, Atapuerca of Spain, Ust Kara-gol of Altai. The indices measured for quantifying mechanical properties include 1) tensile strength, 2) isotrophy, 3) Young’s modulus and 4) wave velocity. The preliminary result is that any significant difference is hardly identified in these indices; the intra-variability of flint-chert group is larger than inter-group variability and the quartz/quartzite group does not show any clear mechanical inferiority in terms of those four indices above. This result introduces a new hypothesis that the physical constraints imposed on the crude nature of the IHRA implements should be pursued other than sheer mechanical indices of quartz and quartzite. 일반적으로 한국의 석영계 석재는 조질 석재(low-quality material)로 이해되고 있지만 이러한 석영계 석재가 과연 어느 만큼이나 열악한 특징을 가지고 있는지 구체적인 정량화 작업을 통해서 양질 석재(high-quality material)와 비교된 예는 없다. 본 고는 기계적 성질면에서 뚜렷하게 우월한 성격을 지니는 유럽의 양질 석재와 한국 임진-한탄강 유역의 조질 석재를 비교하였다. 널리 알려진 유럽의 구석기 유적들-생 타슐 유적을 비롯한 프랑스의 솜므강 유역, 베제르 강 일대의 프랑스 도르도뉴 지역, 스페인 아타푸에르카 유적, 러시아 알타이 지역의 카라-봄 유적 일대에서 채취한 플린트 및 기타 석재들의 다양한 기계적 성질을 측정하고 이를 임진-한탄강 유역의 규암제 석재와 동일한 조건에서 비교ㆍ분석하였다. 분석 결과, 실험실에서 다양한 변수들을 통합하는 주성분분석법을 통해서 양질/중간질/조질 석재는 통계적으로 의미 있는 수준에서 구분이 가능하였다. 그리고 이러한 석재의 질적 구분에는 탄성요인과 인장요인이라는 변수가 크게 작용한다는 것을 알 수 있었다. 이러한 탄성요인과 인장요인은 각각 '타격감'과 '견고함'이라고 정의될 수 있는 고인류가 감각적으로 인지하는 주관적 속성과 관련이 있다고 생각할 수 있다. 따라서 통상적으로 조질/양질이라는 이분법적인 석재의 구분은 어디까지나 고인류의 석재 구분과는 무관한 주관적인 구분일 가능성이 높으며, 석재의 질적 속성은 기계적 성질 및 해당 석재가 지니는 각종 맥락적 효용성까지 포괄할 때 의미를 지닌다는 것을 알 수 있다.

울산지역 청동기시대 편마암류 석기의 산지연구

黃昌漢 한국문화유산협회 2010 야외고고학 Vol.0 No.9

지금까지 청동기시대 석재유물의 산지추정에 대한 연구는 거의 이루어지지 않았다. 본고의 첫 번째 목적은 울산지역의 청동기시대 유적에서 출토된 석재유물 중에서 편마암, 또는 규질편마암으로 동정되고 있는 석부류의 산지를 추정하는 것이고, 두 번째는 이를 통해서 고고학적 해석을 시도하는 것이다. 울산지역은 편마암이 산출되지 않을 뿐 아니라 유수에 의한 유입도 불가능한 지역이므로 산지추정에 적합한 대상이다. 그러나 현실적으로 유물을 파괴분석하여 시료로 제작하는 것은 어려운 상황이다. 따라서 이를 극복할 수 있는 방안으로서 울산지역 출토 편마암류 석부와 유사한 대응암석을 채집하고, 그 암석과 유물의 동일성 여부를 지질학전공자를 통해 검증 받는다. 결론적으로 대응암석을 파괴분석하여 정확한 암석명과 산지를 결정한다. 울산지역출토 편마암류 석부와 동일한 암석은 평해, 울진지역의 태백산편마암복합체에서 확인되었다. 분석결과 석류석 화강암질 편마암, 석류석-근청석-흑운모 편암, 우백질 화강편마암, 규암으로 판명되었다. 이 암석 중에서 규암과 석류석 화강암질 편마암은 평해, 울진지역의 태백산편마암복합체에서 산출되는 특징적인 암석이다. 따라서 울산지역의 편마암류 유물의 산지는 평해, 울진지역으로 판정하는 것이 합리적이다. 울산지역의 편마암류 유물의 편년은 전기 후반에 집중되며 후기 전반까지 지속되다가 검단리단계인 후기 후반에 거의 확인되지 않는다. 울산지역으로의 유입배경은 동북지방 루트의 청동기문화와 지속적인 교류를 나타내는 증거로 추정된다. 편마암류 석부는 기능은 물론 의미적인 요소가 복합적으로 내재되어 있는 것으로 추정되었다. 편마암류 석부는 제작이 어려워 효율적인 석재는 아닌 것으로 판단된다. 그러나 내구성이 좋아 도구로서의 기능은 우수하다. 동시에 석류석이 다량 포함된 석부와 보석세공과 같이 전면을 광택 있게 제작된 석부는 위세품적 성격도 있었을 것으로 추정된다. 교류의 대상으로는 민족지적인 예를 참고로 할 때 혼인 등에 의한 인적교류를 통해 유입되었을 가능성을 추정하였다. The provenance of Bronze Age stone artifacts has rarely been studied. Therefore, the first aim of this paper is to analyze the provence of stone axes excavated from Bronze Age sites in the Ulsan region which have been identified as gneiss or quartzitic-gneiss. Secondly, I will try to provide an archeological explanation based on the results. Gneiss is not present in the Ulsan region, nor can it have been transmitted into the region by running water. As it was difficult to undertake destructive analysis on the actual stone artifacts, I collected rock samples similar to the material of the gneiss stone axes found in the Ulsan region and confirmed their identity with the help of a geologist. It is the provenance of these rock samples which were identified through destructive analysis. It was confirmed that the stone samples identical to the gneiss stone axes of the Ulsan region came from the Taebaeksan gneiss complex of the Uljin region. The samples were identified as granitic gneiss, garnet-cordierite-biotite schist, leucocratic granitic gneiss and quartzite based on the analytical results. Of these rocks, quartzite and garnet granitic gneiss are characteristic of the Taebaeksan gneiss complex of the Uljin and Pyeonhae regions. It is therefore reasonable to assume that the provenance of the gneiss objects of the Ulsan region was the Pyeonghae and Uljin regions. Chronologically, the gneiss artifacts of the Ulsan region are concentrated around the later half of the Early Bronze Age and continue into the early half of the Late Bronze Age. However, they are rarely found in the Geomdanri phase, which is the later half of the Late Bronze Age. It is assumed that the introduction of these artifacts into the Ulsan region is associated with continuous interaction with the Bronze Age culture of the northeastern region. The gneiss stone axes are assumed to have been complex in both function and meaning. Given that gneiss is difficult to work with, it would not have been an efficient material for manufacturing stone tools. However, its durability may have been useful in terms of the function of the stone tools. In addition, stone axes containing garnets and those with polished surfaces may have been used as items of prestige. Ethnographic examples suggest that these items have been exchanged as part of practices of human interchange, such as marriage.

무안반도 소재 석장승의 원암 및 석재 공급지

안건상 ( Kun Sang Ahn ) 한국도서(섬)학회 2010 한국도서연구 Vol.22 No.1

A totem pole is a guardian located in front of villages and temples who protects the village against evil spirits and other calamities. This study is to investigate the sources of rocks and areas of three Jangseungs (Seongnamri Jangseung at the Muaneup, Chongjisaji Jangseung and Beopcheonsa Jangseung at the Mongtanmyeon). Many documents of cultural assets explain the stone source of the Seongnamri Jangseung as a granite. But the rock is lithic-lappilli tuff of the Cretaceous period, which includes lithic various sizes of lithic fragment up to 10cm. The most lithic fragments are deep purple colored tuff and rhyolite. These petrographical features of the stones used for the Seongnamri Jangseung are compared with those of the lappili tuff cropped out nearby, indicating that the Jangseungs are quite similar to the lappili tuff of the Namsan at Muan-up. The literature of Cultural Properties Administration explains the source rock of Chongjisaji Jangseung as a granite. But the rocks are not granite, and differ from each other. The woman`s rock is a conglomerate which has various size of pebbles up to 10cm. The men`s rock is crystal-lappilli tuff which has quartz and feldspars of around 1mm in diameter. Petrographical features indicate that two rocks are derived from conglomerate layer(woman, Kcsm) and crysal tuff(man, Kct) layer of the Cretaceous period around Chongjisa temple site. The source of rocks is not referred to by name in documents for the Beopcheonsa Jangseung. The rock source of Beopcheonsa Jangseung is quartzite. The rock shows mylonitic texture by shear deformation and quartz dyke with 2cm wide. Petrographical features of the Jangseung are quite similar to the quartzite layer(qt) cropped out nearby. In conclusion, three Jangseung stones are not granite and derived from surrounding terrane.

파주지역 규암의 층서관계 규명을 위한 지구화학적-구조지질학적 연구

고희재(Hee Jae Koh),이승구(Seung-Gu Lee),이병주(Byung-Joo Lee) 한국암석학회 2005 암석학회지 Vol.14 No.2

경기도 파주시 월롱면, 광탄면, 조리면 지역에는 다중 습곡 작용을 받은 선캠브리아기 암석이 N10°E 방향의 습곡축을 갖는 2 조의 U형 습곡구조(습곡 Ⅰ과 Ⅱ)를 따라서 분포한다. 습곡구조를 따라 분포하는 10여 매의 규암과 4 매의 석회질 편암은 기원 퇴적암이 순차적으로 반복 퇴적된 것인지, 혹은 1-2 매의 동일한 규암과 석회질 편암이 등사습곡작용에 의하여 반복 분포되는 것인지에 관한 직접적인 증거(퇴적구조)는 발견되지 않는다. 이 논문에서는 U형 습곡이 습곡축을 중심으로 동측과 서측의 양 방향에 분포하는 규암의 상호 연결성을 희토류원소 분포도와 Nd 동위원소비와 같은 지구화학적 방법으로 대비하였다. 습곡구조를 형성하는 규암의 희토류원소 분포도 특성은 경희토류는 편평하고 중희토류가 약간 결핍되어 있다. 또한 Ce의 부(-)의 이상을 보여주는 반면에 Eu의 이상은 거의 존재하지 않는다. 희토류원소 분포도 양상은 습곡축을 중심으로 동-서 양 방향의 규암에 있어서 매우 유사하게 나타났다. 이들 규암의 Nd 모델연대도 습곡축의 양쪽 외곽부에서 내부로 들어오면서 젊어지는 경향을 보여준다. 이와 같이 유사한 희토류원소 분포특성과 Nd 모델연대는 연구지역내에서 습곡축을 중심으로 동측과 서측에 분포하는 규암이 동일한 기원물질로부터 유래되었음을 시사해주는 것으로서 , 충서적 및 구조지질학적 연결과 대비되는 것으로 볼 수 있다. 규암과 호층을 형성하는 운모편암의 희토류원소 분포도 및 Sr, Ba, Eu, Rb과 같은 미량원소의 상관관계도는 운모편암이 규암의 근원 물질과는 다를 가능성을 지시한다. 이는 변성작용, 풍화작용과 같은 지질현상에 의해서도 전체적인 분포 특성이 거의 영향을 받지 않는 희토류원소 지구화학과, 지각내 체류시간을 지시해주는 Nd 동위원소 지구화학이 서로 떨어져 분포하는 퇴적층의 연결성을 추적하는데 유용하게 활용될 수 있음을 지시해준다. The Precambrian quartzite and calc-schist layers experienced multi-folding events are distributed along the two kinds of V-shaped fold (Fold Ⅰ and Ⅱ) with N10°E-directed fold axis in Wollong-myeon, Gwangtan-myeon, Jori-myeon of Paju city, the northeastern part of Gyeonggido. Occurrence of 10 layers of quartzite and 4 layers of calc-schist is not clear whether quartzite and schist layers were deposited sequentially each other or one to two layers of quartzite and schist were distributed repeatedly by isoclinal folding and thrusting, because of lack of sedimentary structures. In this paper, we tried to clarify the correlative relationship among the quartzite beds which are distributed along the U-shaped folds using geochemical tools such as rare earth element (REE) patterns and Nd isotope ratio. Quartzites have characteristics of LREE-flattened, HREE- slightly depleted patterns. They also show Ce negative anomaly whereas there are no Eu anomalies. As a result, quartzite beds occurred along the bilateral sides of fold axis show very similar REE patterns from outer side to inner side of fold. The Nd model age of quartzite layers shows a trend that the inner part of fold is younger than the outer part of it. Such geochemical characteristics suggest that bilateral quartzite beds occurred along the fold axis were derived from the cogenetic source materials. The REE patterns and trace element geochemistry of mica schist intercalated within quartzite indicate that the quartzite and mica schist may be derived from different source materials. Our results suggest that REE and Nd isotope geochernistries may be very useful in clarifying the relationship of sedimentary deposits which do not show stratigraphical and structural connections in the field.

Prospecting of Silica of Naudanda Quartzite, West Central Nepal

Mani Khanal,Naresh Kazi Tamrakar,Dinesh Raj Sharma 대한지질공학회 2024 지질공학 Vol.34 No.3

As the importance of silica is increasing in digital world and other sector, prospecting of silica is the initial process for silica exploration. For prospecting of silica, the Naudanda Quartzite was studied thoroughly. The potential of silica content in the Naudanda Quartzite is presented in very few reports and literatures. Therefore, the study was carried out along the Siddartha Highway and other local roads around the Bhalu Pahad area. The area comprises of mainly phyllite, metasandstone and medium- to coarse-grained orthoquartzite of the Lesser Himalayan metasedimentary sequence. Here orthoquart zite is targeted for the prospecting of silica as quartzite constitutes more than 90% quartz minerals. The study was carried out to prospect the silica resource and compute the mineral reserve in the area. From the route map prepared at 1:2,000-scale along the Bhalu Pahad-Haripala section and columnar section, it is found that the true thickness of the Naudanda Quartzite is 760 m. A geological map was prepared at 1:25,000 scale, and 15 quartzite samples were taken from suitable locations preventing stratigraphical reoccurrence. Five samples were taken randomly from folded zone. Silica grains were counted on the basis of fleet method after thin section preparation of 15 individual samples. More than 95% silica is present on an average. Again, silica content of 5 samples out of 15 were tested chemically and found more than 95% silica concentration. For reserve calculation, silica grade was taken 95% and the reserve was computed on the basis of three cross-sections. It is found that the total volume tonnage is 2.6 billion ton of silica content, and concluded that the silica present in the rock is economic and minable.

Unconventional resources in Algeria: appraisal result from the Hamra Quartzite reservoir

Soumya Benayad,박영수,Rabah Chaouchi,Naima Kherfi 한국지질과학협의회 2013 Geosciences Journal Vol.17 No.3

Unconventional resources have been widely discovered within the Ordovician rocks (Hamra Quartzite reservoir) of a number of basins in Algeria, including the giant Hassi Messaoud oil-field. This study aims to provide an appraisal of the major characteristics of the Hamra Quartzite reservoir within the southern peripheral area of the Hassi Messaoud field. Petrographically, quartz grains in this reservoir are considered to be mature quartz arenites characterized by pervasive quartz overgrowth. Reservoir porosity is dominated by secondary intergranular dissolution porosity. The diagenetic sequence of the Hamra Quartzite reservoir occurred in three phases: eodiagenesis (early), mesodiagenesis (mid), and telodiagenesis (late) phases. These phases are directly related to tectonic events that affected the study area, and are controlled mainly by the Hercynian unconformity. The Hamra Quartzite reservoir was highly silicified during the pre-Hercynian phase. Compaction and cementation are the principal factors controlling reservoir degradation. The reservoir is faulted and fractured, and fractures ranging from partially open to closed are observed in cores. Petrophysically, the reservoir displays low porosity and permeability values. However, moderately porous and permeable sandstone is present toward the southeastern part of the studied reservoir.

남극 북빅토리아랜드 고압 변성대에 산출하는 함망간규암 내 저어콘과 석영의 산소동위원소 조성

김태환 한국광물학회 2024 광물과 암석 (J.Miner.Soc.Korea) Vol.37 No.4

망간이 풍부한 석영질 변성퇴적암류, 소위 함망간규암은 처트가 우세한 심해퇴적물 기원으로, 조산대에 드물지 않게 산출한다. 본 연구에서는 남극 북빅토리아랜드의 고압 변성대에 산출하는 함망간규암 내 저어콘과 석영의 산소동위원소 조성을 분석하였다. 연구결과는 함망간규암에서 저어콘과 석영의 산소동위원소 조성을 보고한 첫 사례이다. 저어콘과 석영 결정들은 각각 2‰ 범위의 δ18O 값을 가지며 평균값은 각각 18.13 ± 0.25‰(2σ)과 20.73 ± 0.26‰(2σ)으로 퇴적모암의 주구성요소인 처트의 퇴적당시 중간값(~25-28‰)보다 낮다. 고압 변성작용 동안 활동하는 유체의 산소동위원소 조성이 함망간규암의 저어콘과 석영의 δ18O 값보다 현저히낮음을 함께 고려하면, 처트가 우세한 모암의 산소동위원소 조성이 터레인 부가와 연관된 섭입대 변성작용으로인해 변화했음을 알 수 있다. 저어콘-석영 간 평형상태 동위원소 분별 계산결과는 유체활동으로 인한 함망간규암 모암의 산소동위원소 재평형이 후퇴변성작용보다는 에클로자이트상 전진 내지 최고변성작용 동안 이루어졌음을 시사한다. Mn-rich quartzose metasedimentary rocks, or manganiferous quartzites originate from chert-dominated deep-sea sediments, and their occurrence is not uncommon in orogenic belts. I analyzed oxygen isotopic compositions of zircon and quartz in a manganiferous quartzite from high-pressure metamorphic belt in northern Victoria Land, Antarctica. This study reports for the first time the oxygen isotopic compositions of zircon and quartz from manganiferous quartzites in the world. Zircon and quartz yielded isotopic variation within 2 ‰ range, and mean δ18O values of 18.13 ± 0.25 ‰ (2σ) and 20.73 ± 0.26 ‰ (2σ), respectively. These are lower than the median value (~25-28 ‰) of chert, a primary component of the sedimentary protolith, at the time of deposition. Combined with much lower oxygen isotopic composition represented by fluid activity during high-pressure metamorphism, the oxygen isotopic composition of the chert-dominated protolith was reset and lowered by subduction-zone metamorphism in association with terrane accretion event. Calculation of equilibrium isotope fractionation between zircon and quartz implies that the re-equilibration of the oxygen isotopic composition of the manganiferous quartzite protolith by the deep fluid activity took place during the eclogite-facies prograde-to-peak metamorphism rather than retrograde one.