• The Journal of the Petrological Society of Korea
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• v.18 no.3
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• pp.255-267
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• 2009

The intrusive rocks in the Hudongri area, Chuncheon located in central Gyeonggi Massif consist of gabbroic diorite and diorite. K-Ar age of biotite separated from diorite sample records middle Triassic age of 228 Ma. The intrusives are characterized by enrichment of MgO, Ni and Cr as well as large ion lithophile elements such as Sa and Sr, which is indicative of derivation of magma from enriched mantle. The intrusives also have enriched Sr-Nd isotopic compositions, which appear to result from a long-term incompatible element enriched mantle source with an effect of crustal contamination. Occurrence of abundant hydrous minerals such as amphiboles and biotite rather than anhydrous minerals of pyroxene and olivine in mafic intrusive as well as being plotted in volcanic arc field in tectonic environment discrimination diagram indicate the mafic-intermediate intrusives in the Hudongri area, Chuncheon were derived from mantle material enriched by subduction.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.1
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• pp.13-24
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• 2022

The Arctic Ocean is very sensitive to global warming and Arctic Ocean sediments provide a records of terrestrial climate change, analyzing their composition helps clarify global warming. The gravity core sediment ARA07C-St02B was collected at the East Siberian margin during an Arctic expedition in 2016 on the Korean ice-breaking vessel ARAON, and its provenance was estimated through sedimentological, mineralogical and geochemical analysis. The core sediment was divided into four units based on sediment color, sand content and ice-rafted debris content. Units 1 and 3 had higher sand and ice-rafted debris contents than units 2 and 4, and contained a brown layer, whereas units 2 and 4 were mainly composed of a gray layer. Correlation analysis using the adjacent core sediment ARA03B-27 suggested that the sediment units were deposited during marine isotope stage 1 to 4. The bulk mineral, clay mineral, and geochemical compositions of units including a brown layer differed from units including a gray layer. Bulk and clay mineral compositions indicated that coarse and fine sediments had a different origin. Coarse sediments might have been deposited mostly by the East Siberian Coastal Current from the Laptev Sea and the East Siberian Sea or by the Beaufort Gyre from the Chukchi Sea, whereas fine sediments might have been transpoted mostly by currents from the East Siberian Sea, the Chukchi Sea and the Beaufort Sea. Some of the coarse sediments in unit 1 and fine sediments in unit 3 might have been deposited by iceberg ice, sea ice or current from the Beaufort Sea and the Canada Archipelago. Investigating the geochemical composition of the potential origins will elucidate the origin and transportation of the study area's core sediments.

• Korean Journal of Heritage: History & Science
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• v.56 no.3
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• pp.196-212
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• 2023

This study identifies the origin of stone remains (pavement and banister stones) excavated from the first burial site of King Jeongjo through petro-mineralogical analysis in a quarry and examines the relationship with the stone remains from Geolleung (King Jeongjo's Tomb). The excavated stones from the first burial site of King Jeongjo are all light gray fine-grained biotite granite, and mainly contain quartz, feldspar, and biotite. The magnetic susceptibility of the stones ranges from 5.55 to 12.10 (average 7.00) (SI unit). According to old documents, the quarrying sites of the stones were Mts. Aengbong and Yeogisan (Godeung-dong District, Suwon), and we found a fine-grained biotite granite outcrop behind Mr. Aengbong (currently the site of Yeonggwang Apartment) with a geological survey, and it was petrologically similar to the stone remains from the first burial site. The magnetic susceptibility of the outcrop rocks was 5.15 to 7.24 (SI unit), and their petro-mineral and geochemical characteristics were found to be the same as those of the first buried site and Geolleung Tomb. It was confirmed that most of the stone elements in the first burial site were reused to build Geolleung Tomb while moving the grave. Only the pavement and banister stones seem to have been discarded in the first grave site without being transferred. This is because the size of the new burial mound became larger than the first grave during construction because Queen Hyoui (the consort of King Jeongjo) died and was buried together with the king in the same tomb, and the stone blocks did not fit a grave that size. With these research results, it was possible to compare and examine the old records and scientific analysis data, and they are expected to be used as basic source material in related research.

• Economic and Environmental Geology
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• v.43 no.2
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• pp.163-176
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• 2010

We report twenty data for early lavas erupted during the initial period of formation of Jeju Island on the basis of review on 539 data of whole-rock greochemistry and $^{40}Ar/^{39}Ar$ age dating out of mainly core samples from 69 boreholes drilled in the lower land since 2001 and 66 outcrop sites. Out of 69 boreholes, the early lava flow units are identified from samples collected from Beophocheon (EL 235 m, 210 m deep), Donnaeko (EL 240 m, 230 deep), Donghong-S (EL 187 m, 340 m deep), 05Donghong (EL. 187.6 m, 340 m deep), Dosoon (EL 305 m, 287 m deep), Sangye (EL 230 m, 260 m deep), Mureung-1 (EL 10.2 m, 160 m deep), and Gapa (EL 17.5 m, 92 m deep), which are located in the southern and southwestern portion of Jeju Island. While, the well-known outcrops from Sanbangsan, Wolrabong, Wonmansa, and Kagsubawi are also reconfirmed. $^{40}Ar/^{39}Ar$ age dating results of these lavas range from 1 Ma to 0.7 Ma, indicating that the data can be useful to constrain on age and geochemical characteristics of early lava effusion period in the formation of Jeju Island. Especially, samples with trachybasalt in composition collected from 143 m to 137 m, and from 135 m to 123 m below ground surface at 05Donghong hole have the oldest ages, $992\pm21$ Ka and $988\pm38$ Ka, respectively. This study suggests that in Jeju Island the first lava with trachybasalt in composition may have effused around 1 Ma ago, and the effusion style and chemical compositions of lavas must have changed to the formation of lava domes with trachyte-trachyandesite-basaltic trachyandesite and the eruption of lavas with alkali basalt and trachybasalt intermittently during the period from 0.9 Ma to 0.7 Ma ago. It also indicates that the initial lava flows below the ground are intercalated with or underlain by the Seoguipo Formation except for several exposed domal structure areas such as Sanbangsan and Kagsubawi, implying that the early lava effusion may have intermittently and sporadically occurred with nearby hydrovolcanism and sedimentation.