이호준 Hojun Lee , 김영재 Youngjae Kim

DOI:10.22807/KJMP.2025.38.1.1 Vol.38(No.1) 1-8, 2025

Although numerous studies have reported the structural and chemical properties of the apatite endmembers, fluor-, hydroxyl-, and chlorapatite, through field and experimental observations, theoretical understanding of their thermodynamic stabilities and structural characteristics at the atomic and molecular level remains limited. In this study, the ground-state structures of the apatite endmembers are modeled using quantum mechanical methods to evaluate the thermodynamic stability of column anions (F^-, OH^-, Cl^-) along the c-axis. In the energy-optimized structures, fluoride ions are found to be positioned at z = 0.25/0.75, hydroxide ions at z = 0.22/0.72, and chloride ions at z = 0.43/0.92. Among the apatite endmembers, hydroxylapatite exhibits the largest energy variations (approximately 50 kJ/mol) with changes in the position of hydroxide along the c-axis, influenced by the orientation of the O-H bond in the hydroxide ion. These results suggest that the thermodynamic stability of column anions in apatite is controlled by the electrostatic interactions between constituent ions as well as spatial constraints by neighboring ions. This study establishes a quantitative framework for examining the thermodynamic stability and structural properties of apatite endmembers, offering insights into natural apatite structures.

불화인회석, 수산화인회석, 염소인회석, 컬럼 음이온(F. OH. Cl)^-, 양자역학 모델링, Fluorapatite, Hydroxylapatite, Chlorapatite, Column anions (F. Quantum mechanical modeling

박진섭 Jinsub Park , 양기호 Kiho Yang

DOI:10.22807/KJMP.2025.38.1.9 Vol.38(No.1) 9-16, 2025

This study investigates the mineralogical and geochemical properties of multi-nucleated ferromanganese nodule obtained from the tabletop of the Magellan Seamounts OSM-XX, aiming to elucidate their formation process. During the 2021 Western Pacific exploration conducted by the Korea Institute of Ocean Science and Technology (KIOST), ferromanganese nodule samples were collected from the OSM-XX seamount. A ferromanganese nodule sample with two nuclei was selected for geochemical and mineralogical analysis. Micro X-ray fluorescence (XRF) analysis was employed to conduct two-dimensional elemental distribution and quantitative analysis, while Raman spectroscopy was used for mineralogical composition analysis. The ferromanganese nodule, approximately 6.41 cm in the long axis, exhibited two distinct nuclei, each surrounded by a dense structure, with a porous, thick layer containing sediments on the outer surface. The manganese oxide layer of the nodule exhibited a relatively high Mn/Fe ratio of 2.35 (ranging from 0.95 to 4.64), indicating a mixed type origin influenced by both hydrogenetic (Mn/Fe < 2.5) and diagenetic (Mn/Fe > 2.5) processes during its formation. Vertical variations in elemental composition along three directions, lacking symmetry around the nuclei, suggest the fusion of two separate nodules with distinct nuclei during formation. Mineralogical analysis revealed that the outer layer is composed of the manganese oxide mineral vernadite, indicating a subsequent hydrogenetic origin.

서태평양, 마젤란 해산군, 다중핵 망가니즈 단괴, 혼합기원 망가니즈 단괴, Western Pacific, Magellan seamount cluster, Multi-nucleated Ferromanganese nodule, Mixed-type Ferromanganese nodule

고상모 Sang-mo Koh , 오트곤-에르덴다바수렌 Otgon-erdene Davaasuren , 이범한 Bum Han Lee , 신우창 Wochang Shin

DOI:10.22807/KJMP.2025.38.1.17 Vol.38(No.1) 17-37, 2025

This study investigates the mineral chemistry of coarse-grained mica (muscovite) and fine-grained mica (sericite) and interprets the alteration processes leading to sericitization of feldspar and muscovite. EPMA analysis of 30 rock samples (72 sericite and 52 muscovite grains) revealed that fine grained mica (sericite) is enriched in SiO₂, MgO, and FeO, whereas coarse grained mica (muscovite) has higher Al₂O₃ and Na₂O contents. Both minerals exhibit high K₂O contents (11.37% and 11.13%, respectively). The substitution of Al in octahedral sites by Fe and Mg results in muscovite-phengite compositions, classifying them as phengitic muscovite. Regional comparisons indicate that Yeongdong sericite has the highest K₂O content (11.37%) and the lowest Cr₂O₃ content (0.02%). In contrast, hydrothermal sericite from gold-bearing quartz veins (e.g., Narim Au deposit in Korea, Barramiya Au deposit in Egypt, and several Au deposits including Dayin-Gezhung deposit in China) exhibits higher Cr₂O₃ contents, reflecting its hydrothermal origin. Alteration index (AI) and chlorite-carbonate-pyrite index (CCPI) diagrams confirm that sericitization is the dominant alteration process in the region. Feldspar in gneiss were altered to sericite by meteoric water infiltration along fractures into the brittle-ductile transition zone. Muscovite in gneiss and schist transformed into sericite through mechanical breakdown during ductile deformation, resulting in grain-size reduction. This study elucidates the formation and alteration processes of sericite in the Yeongdong area, highlighting its mineral-chemical characteristics. The findings indicate that sericite evolved from muscovite to phengite due to element substitution during regional metamorphism (retrogressive) and ductile deformation.

영동지역, 견운모, 펜자이트질 백운모, 견운모화작용, Yeongdong area, Sericite, Phengitic muscovite, Sericitization

이유나 Yu Na Lee , 손민경 Min Kyeong Son , 김현나 Hyun Na Kim

DOI:10.22807/KJMP.2025.38.1.39 Vol.38(No.1) 39-53, 2025

Surface fine particles significantly influence dissolution kinetics and reaction mechanisms in mineral-fluid interactions, potentially inhibiting the observation of particle morphology and dissolution reactions. In this study, we systematically compared the efficiency and extent of surface alteration associated with four distinct fine particle washing methods―direct washing, soaking and washing, stirring washing, and ultrasonic washing―applied to quartz powder. Additionally, particle size analysis was conducted to assess the necessity of washing for ensuring sample homogeneity. Direct washing resulted in minimal particle alteration but exhibited low efficiency in washing fine particles. Soaking and washing facilitated the partial dissolution of ultrafine particles and effectively removed them from particle surfaces; however, extended dissolution led to surface weathering. Stirring washing effectively dispersed fine particles through particle collisions, yet it generated new ultrafine particles. Ultrasonic washing demonstrated the highest fine particle washing efficiency, although slight abrasion was observed along particle edges. Particle size analysis revealed that the as-received quartz powder exhibited heterogeneous particle size distribution with a significant presence of fine particles, indicating that sieving is insufficient to obtain a homogeneous sample. Our study highlights the necessity of selecting an optimal sample pretreatment method based on specific experimental objectives and conditions. The optimization of fine particle washing methods is expected to enhance the reliability of sample preparation for future mineral-fluid interaction experiments.

석영, 미세입자 세척, 광물-유체 반응, 표면 특성, 입도, Quartz, Fine-particle washing, Mineral-fluid interaction, Surface characteristics, Particle size distribution

임보성 Boseong Lim , 김민철 Min-cheol Kim , 하상민 Sangmin Ha , 김광희 Kwang-hee Kim , 손문 Moon Son

DOI:10.22807/KJMP.2025.38.1.55 Vol.38(No.1) 55-75, 2025

Detailed geological mapping and structural analysis were performed in the Bukpyeong Basin, which is located in Donghae and Samcheok cities, to interpret the geometry, extension mode, and evolution of the basin. The Bukpyeong Basin is a wedge-shaped basin that extends about 10 km in the NNE-SSW direction with a maximum width of about 4.7 km in the north-northeast. The basin-fill consists of non-volcanogenic siliciclastic sediments showing fining-upward sequence with sorting and roundness increasing upward. Based on the lithofacies, the basin-fill is classified into three units A, B, and C, mainly composed of boulder-sized breccias, interlayered conglomerates and gravelly sandstones, and massive mudstones and fine-grained sandstones, respectively. The basement rocks adjacent to the western margin are systematically tilted toward the southeast, while those in the east shows a slightly dispersed dip direction toward the west on average. The west of the basin is bounded by a fault system that consist of the NE- to NNE-striking normal faults and associated NNW- to NW-striking transfer faults, while the eastern boundary is an unconformity. In addition, the length and displacement increase as the bounding normal fault is located in the north further. These sedimentary and structural features of the basin are very similar to those of other Middle Miocene basins along the eastern coast of the Korean Peninsula. It is therefore interpreted that the Bukpyeong Basin is a half-graben basin, which has also undergone a propagation rifting from NNE to SSW. It is also inferred that the extension age of the basin corresponds to the sedimentation age of the Yeonil Group (ca. 17-10 Ma).

북평분지, 연일층군, 전파열개, 마이오세 퇴적분지, 동해의 확장, Bukpyeong basin, Yeonil group, Propagation rifting, Miocene sedimentary basin, East sea opening