• 한국지구과학회:학술대회논문집
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• 2006.02a
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• pp.230-234
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• 2006

본 연구에서는 미분화 운석 중 오디너리 콘드라이트를 주사전자 현미경으로 관찰하여 열변성, 충격 변성 정도, 지구상에서의 풍화 정도에 따라서 그 구성 성분과 조직이 어떤 변화를 보이는지 알아보았다. 이를 위해 15개의 오디너리 콘드라이트에 대해 각각 연마편 및 연마박편을 준비하였으며, 주사전자 현미경 사진을 이용하여 열변성 단계별로 콘드률과 기질의 경계를 비교하였다. 열변성이 증가할수록 콘드률과 기질의 경계는 점차 모호해 진다. 충격변성을 받았는지의 유무는 감람석을 관찰하여 비교적 쉽게 인지할 수 있다. 충격변성을 받지 않은 콘드률 내의 감람석은 완전 소광과 불규칙적인 깨짐을 보이지만 충격변성을 받은 경우 파동소광과 규칙적인 깨짐을 보인다. 지구상에서 풍화를 받은 경우 철-니켈 금속의 산화가 가장 먼저 진행된다. 풍화에 의한 철산화물은 맥상으로 나타나거나 기존의 철-니켈 금속을 치환하여 나타난다. 철산화물에 의해 풍화를 받은 콘드라이트는 전체적으로 갈색을 띄게 된다.

• Bulletin of the Korean Space Science Society
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• 1998.10a
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• pp.11-11
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• 1998

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.71.2-71.2
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• 2018

태양계 질량의 대부분은 플라즈마, 기체, 또는 액체 상태로 존재하며, 극히 일부만이 고체 즉 암석과 광물로 존재한다. 하지만, 반응 특히 혼합(mixing)이 일어나는 속도가 매우 느린 고체의 특성상 태양계의 탄생과 진화 과정의 기록은 고체태양계 물질에 더 잘 보관되어 있다. 지구를 제외한 고체 태양계 물질을 확보하기 위해서는 지구로 낙하한 암석인 운석(meteorites)을 발견하거나, 우주로 나가 시료를 가져와야 한다. 아폴로 미션(Apollo mission)에 의한 월석(lunar rocks) 채취(Papike et al., 1998), 하야부사 미션(Hayabusa mission)에 의한 소행성(asteroid) 시료 채취(Nakamura et al., 2011), 스타더스트 미션(Stardust mission)에 의한 혜성 시료 채취(Zolensky et al., 2006) 등이 후자에 속한다. 능동적으로 가져온 시료는 아직까지는 그 종류와 양에서 운석에 비해 매우 부족하므로 현재까지 우리가 알고 있는 고체 태양계에 관한 대부분은 운석 연구를 통해 얻어졌다. 운석은 크게 미분화운석 즉 콘드라이트(chondrites)와 분화운석(differentiated meteorites)으로 구분한다. 분화운석 중 일부는 달운석(lunar meteorites) 또는 화성운석(martian meteorites)이며, 나머지 분화운석과 콘드라이트는 암석-지구화학적 특징과 성인적 연관성에 의해 다양한 그룹으로 세분되는데 각 그룹은 하나의, 또는 둘 이상의 매우 유사한, 소행성에서 유래한 것으로 해석된다(Krot et al., 2014; 최변각 2009). 다양한 종류의 운석과 구성 광물에 포함된 기록으로는 (1) 태양계 이전 존재한 항성의 대기에서 생성된 광물, 즉 선태양계 광물(presolar grains), (2) 태양계 성운 탄생과 각 진화 단계의 정확한 시기, (3) 태양계 성운의 화학조성-동위원소 조성, 온도-압력 조건 등을 포함한 물리-화학적 특징, (4) 가스-먼지로부터 미행성, 소행성, 행성으로의 진화 과정, (5) 행성 진화의 열원, (6) 소행성 핵의 생성 과정 등이 있다. 강연에서는 이들을 간략히 살펴보고자 한다. 운석연구 등을 통해 태양계 생성과 진화과정에 관한 다양한 정보가 축적되었지만, 앞으로 연구할 것들이 더 많다. 또한 태양계 물질 중에는 운석의 형태로 지구로 들어왔거나 앞으로 들어올 수 있는 것도 있지만 그렇지 않은 것도 있다. 가스나 기체의 경우가 그러할 것이며, 고체지만 결합이 약해 일부라도 원형을 유지한 채 대기권을 통과 할 수 없는 것도 있을 것이다. 또 공전궤도나 중력 등 물리적 이유로 지구권 진입이 불가능한 것도 있다. 이러한 태양계 구성원에는 우리가 아직까지 얻지 못한 정보들이 다량 보존되어 있을 것이다. 미래의 태양계탐사가 기대되는 이유 중 하나이다.

• Economic and Environmental Geology
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• v.33 no.6
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• pp.447-467
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• 2000

This study was carried out geochemically and mineralogically to define how Kunsan shore sediments are related to their terrestrial source rocks in the region of Keum River Basin, western Korea. As a whole the chemical composition for major elements, trace elements and rare earth elements analysis from shore sediments and river bed sediments doesn't show the big difference, and especially rare earth elements chondrite normalized patterns are almost same. Heavy minerals of shore sediments are identified as hornblende, epidote, ilmenite, garnet, hematite, magnetite, sphene and rutile. Compared with Taean Area of Seo et al. (1998) and Byeonsan Area of Kwon et al. (1999), Kunsan shore sediments of this study area were origined mostly from Keum River Basin.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.3
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• pp.199-212
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• 2023

Diffusion is a powerful tool to understand geological processes recorded in terrestrial rocks as well as extraterrestrial materials. Since the diffusive exchange of elements or isotopes may have occurred differently in the solar nebula (high temperature and rapid cooling) and on the parent bodies (fluid-assisted thermal metamorphism at relatively low temperature), it is particularly important to model elemental or isotopic diffusion profiles within the mineral grains to better understand the evolution of the early solar system. A numerical model with the finite difference method for the fast grain boundary diffusion was established for the exchange of elements or isotopes between constituent minerals in a closed system. The fast grain boundary diffusion numerical model was applied to 1) ²⁶Mg variation in plagioclase of an amoeboid olivine aggregate (AOA) from a CH chondrite and 2) Fe-Mg interdiffusion between chondrules, AOA, and matrix minerals in a CO chondrite. Equilibrium isotopic fractionation and equilibrium partitioning were also included in the numerical model, based on the assumption that equilibrium can be reached at the interfaces of mineral crystals. The numerical model showed that diffusion profiles observed in chondrite samples likely resulted from the diffusive exchange of elements or isotopes between the constituent minerals. This study also showed that the closure temperature is determined not only by the mineral with the slowest diffusivity in the system, but also strongly depends on the constituent mineral abundances.

• The Journal of the Petrological Society of Korea
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• v.8 no.2
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• pp.81-91
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• 1999

The area of the study is located in Ogcheon district, middle part of Ogcheon Fold Belt. The area is covered by metasedimentary rocks of Ogcheon Supergroup at northern, eastern and southern part. Jurassic Ogcheon granite which intruded into Ogcheon Supergroup at central part, was intruded by Cretaceous quartz porphyry at western part. The granite consists of quartz, plagioclase, alkali feldspar, biotite, sphene, apatite, epidote, opaque and so on. It is generally characterized by grey to light grey, medium-grained, mafic enclave and partly weak foliation. In terms of geochmical compositions, the granite is felsic, peraluminous, subalkaline and calc-alkaline, and it was differentiated from single granitic magma. It shows parallel LREE enrichment and HREE depletion patterns with 0.84 Eu negative anomaly, which has REE variation trend and anomaly value similar to Jurassic granites in Korea. From charactristics of petrology, mineralogy and geochmistry, it may be interpreted that the Ogcheon granite body was derived from melting of I-type crustal material related to syn-collisional tectonic setting and emplaced more or less rapidly into the Ogcheon Supergroup.

• Analytical Science and Technology
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• v.20 no.6
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• pp.468-473
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• 2007

The chemical composition distribution of the surface samples collected from the loess plateau in China were estimated. Major elements concentration distribution difference between 10 different sampling site were not found except sample 3. This sample had higher contents of Ca, Mg, LOI and lower contents of Si, Fe, P, Na, Ti. And also, minor element contents such as Ba, Cr, Nb, Pb, Rb, Zr, V were lower than other samples. UCC-normalized abundances of the most elements were within $0.5-1.5{\times}UCC$ and Cr showed enrichment aspect. Rare-earth element (REE) analysis results showed light REE enriched pattern compared to heavy REE with negative Eu anomaly in condrite-normalized REE pattern.

• Economic and Environmental Geology
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• v.30 no.6
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• pp.603-612
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• 1997

Cretaceous sedimentary-volcanoclastic formations of the Kyeongsang Supergroup were intruded by granitic rocks in the late Cretaceous and early Tertiary. In the Euiseong and Shinryeong area, these intrusives have various compositions including gabbro, diorite，biotite granite and feldspar porphyry. Associated volcanic rocks consist of two chemically distinct types: the bimodal suite of basalt and rhyolite in the Keumseongsan caldera, and the felsic suite of andesite and rhyolite in the Sunamsan-Hwasan calderas. Most rocks are subalkaline, and follow a typical differentiation path of the calc-alkaline magma. The granitic rocks can be distinguished chemically from the volcanics by high Zr/Y ratios. Differences in Zr/Y and K/Y ratios between the two volcanic suites can be accounted for by mantle source and fractionation. Chondrite-normalized trace element abundances of granitic rocks are depleted in Th and K, whereas those of the Keumseongsan rhyolites are depleted in Sr and Ti. Rb, La and Ce is enriched in rhyolites of the Sunamsan-Hwasan calderas. $Rb-SiO_2$ and Rb-Y+Nb discrimination diagrams suggest that the intrusives and volcanics have a volcanic arc setting. K-Ar ages indicate four plutonic episodes : diorite (89 Ma), granite (66~62 Ma), granite and porphyry (55~52 Ma) and gabbro (52~45 Ma), and two volcanisms : bimodal basaltic and rhyolitic volcanism (71~66 Ma) in the Keumseongsan caldera, and felsic andesitic and rhyolitic volcanism (61~54 Ma) in the Sunamsan-Hwasan calderas. Geochemical and age data thus suggest that the igneous rocks are related to several geologic episodes during the late Cretaceous to early Tertiary.

• The Journal of the Petrological Society of Korea
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• v.9 no.2
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• pp.70-83
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• 2000

The purpose of this study is to identify the petrographic and geochemical characteristics of four granitic masses and clanfy for the origin and relationship among the masses. These granitic rocks are distributed in the eastern part of Yangsan fault in the Kyongsang basin, southeastern part of Korea. Based on the mineralogy and texture, the granitic rocks are divided into three facies; granodiorite, porphyritic fine-grained granite, and equigranular granite. According to the result of modal analysis, northern part and most of the southern part of Daebon granitic rocks are plotted in granodiorite field and the rest part of the xocks are plotted in granite field. These granitic rocks belong to the sub-alkaline series, and are subdivided into calc-alkaline series. The rare earth elements normalized bv chondrite show LREE is more enriched than HREE and the lowest values in O-w m- i t e and Daebon equigranular granite. The crystallization pressures and temperatures of minimum melt compositions of granitic rocks estimated from the study area are about 0.5-1 kbar and $700~820^{\circ}C$, respectively. Referring to the petrographic characteristics, geochemical data and radiogenic age data, Oyu granite was emplaced in the Paleocene, but Daebon granodiorite, Sanseo porphyritic granite, and Hoam equigranular granite are co-magmatic differentiation products, were emplaced in the Eocene.

• The Journal of the Petrological Society of Korea
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• v.13 no.3
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• pp.161-177
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• 2004

The Cretaceous pink granites of the finan area, southwestern Ogcheon belt, are adjacently developed in the eastern part (Keg) and western part (Kwg) as stocks, respectively. Keg of rounded shape occur as mainly medium-coarse grained rocks, whereas Kwg of ellipsoidal shape occurs as medium-coarse grained ones with partly porphyritic and fine-grained textures. Miarolitic cavities of them are often seen and can be observed more frequently in Kwg than Keg. Rose and counter fracture diagrams of the two granites show that Keg and Kwg have more potentiality of non-dimension and dimension to non-dimension stones, respectively. Physical properties such as porosity and absorption ratio have 0.25% and 0.65％, and 0.43% and 1.11%, respectively, which could suggest that emissions of gas phase at later magma stages are abundant in Kwg than those of Keg. From the major and trace elements petrochemisoy, they belong to acidic, peraluminous and calc-alkaline rocks, showing that Kwg are later product than Keg of the same granitic parent magma. REE concentrations normalized to chondrite value have trends of gradual and parallel enriched LREE and depleted HREE. Eu negative anomalies of Kwg are far more severe than those of Keg, which suggest that plagioclase fractionation in Kwg was much stronger than that of Keg. In the magnetic susceptibility vs. petrochemical and modal parameters, they all belong to magnetite-series and I-types, and can be classified as weakly-moderately ferromagnetic rocks. And the above relations could suggest that their susceptibility values are more mainly depended on ferromagnetic opaques than ferromagnetic and paramagnetic assemblages (Bt ＋ Ch ＋ Ser ＋ Op).