• Journal of the Mineralogical Society of Korea
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• v.25 no.4
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• pp.283-293
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• 2012

In order to have better insights into the chemical differentiation of Earth from its magma ocean phase to the current stratified structure, detailed information of crystallization kinetics of silicate melts consisting of the magma ocean is essential. The structural transitions in oxide glasses and melts upon crystallization provide improved prospects for a systematic and quantitative understanding of the crystallization processes. Here, we report the $^{27}Al$ 3QMAS NMR spectra for sol-gel synthesized $Al_2O_3$ glass with varying temperature and annealing time. The NMR spectra for the amorphous $Al_2O_3$ show well-resolved Al coordination environments, characterized with mostly $^{[4,5]}Al$ and a minor fraction of $^{[6]}Al$. The fraction of $^{[5]}Al$ in the alumina phase decreases with increasing annealing time at constant temperature. The NMR results of $Al_2O_3$ phases also imply that multiple processes (e.g., crystallization and/or changes in structural disorder within glasses) could involve upon its phase transition. The current results and method can be useful to understand crystallization kinetics of diverse natural and multi-component silicate glasses and melts. The potential result may yield atomic-level understanding of Earth's chemical evolution and differentiation from the magma ocean.

• ALGAE
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• v.34 no.2
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• pp.177-185
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• 2019

Ecklonia cava is popular in Korea as a marine functional materials. E. cava is generally collected and used on the coast of Jeju Island. However, the continuous use of collected natural E. cava may be limited because difficult to secure throughout the year and may be exposed to environmental pollution. Jeju magma seawater (MSW) was known to be significant advantages such as safety, cleanness, stability, and functional improvement. Attempts have been reported on application of MSW to the culturing of macro- and microalgae and showed improved results. Thus, the objective of the present study was to explore the anti-melanogenesis activity of brown seaweed E. cava (E. cava cultured with MSW [MSWE]) extract cultured in tanks with MSW of Jeju Island to evaluate the possibility of cosmeceutical industrial application. MSWE extract showed the higher polyphenolic and dieckol contents than natural E. cava (NE) extract. Anti-melanogenesis activity of MSWE extract and NE extract are tested and compared using tyrosinase and dihydroxyphenylalanine (DOPA) oxidation inhibition assay. MSWE extracts evidenced more effective tyrosinase and DOPA oxidation inhibition activity than that of the NE extracts and the commercial whitening agent, arbutin. MSWE extracts also markedly inhibited melanin synthesis and decreased the expression of melanogenesis-related protein in ${\alpha}$-melanocyte stimulating hormone-stimulated B16F10 melanoma cells without cytotoxicity. These results suggest that MSW cultivation process would be more effective in releasing bioactive compounds with whitening effect from seaweed such as E. cava at an industrial scale.

• 한국지구물리탐사학회:학술대회논문집
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• 2004.06a
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• pp.232-237
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• 2004

Anatahan Volcano in the Commonwealth of the Northern Mariana Islands (CNMI) erupted for the first time in recorded history on 10 May 2003. The underwater acoustic records of earthquakes, explosions, and tremor produced during the eruption were recorded on a sound-channel hydrophone deployed in February 2003. Acoustic propagation models show the seismic to acoustic conversion at Anatahan is particularly efficient, aided by the slope of the seamount toward the hydrophone. The hydrophone records confirm the onset of earthquake activity at 01:53Z on 10 May, as well as the onset (at ${\~}$06:20Z) of continuous, low-frequency (5-40 Hz) acoustic energy that is likely volcanic tremor related to magma intrusion. The hydrophone recorded a total of 458 earthquakes associated with the eruption. To predict the character of acoustic signals generated from Anatahan, we developed a moment-tensor representation of a volcano-seismic source that is governed by the geometry of the source and the physical properties of the magma. A buried magmatic pipe model was adopted, and numerically modeling source parameters such as the pipe radius and magma viscosity enable us to grasp the inward nature of Anatahan Volcano.

• Journal of Ecology and Environment
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• v.29 no.2
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• pp.175-183
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• 2006

The discovery of deep-sea hydrothermal vents and their ecosystems is a monumental landmark in the history of Ocean Sciences. Deep-sea hydrothermal vents are scattered along the global mid-ocean ridges and back-arc basins. Under sea volcanic phenomena related to underlying magma activities along mid-ocean ridges generate extreme habitats for highly specialized communities of animals. Multidisciplinary research efforts during past three decades since the first discovery of hydrothermal vents along the Galapagos Rift in 1977 revealed fundamental components of physiology, ecology, and evolution of specialized vent communities of micro and macro fauna. Heterogeneous regional geological settings and tectonic plate history have been considered as important geophysical and evolutionary factors for current patterns of taxonomic composition and distribution of vent faunas among venting sites in the World Ocean basins. It was found that these communities are based on primary production of chemosynthetic bacteria which directly utilize reduced compounds, mostly $H_2S$ and $CH_4$, mixed in vent fluids. Symbioses between these bacteria and their hosts, vent invertebrates, are foundation of the vent ecosystem. Gene flow and population genetic studies in parallel with larval biology began to unveil hidden dispersal barrier under deep sea as well as various dispersal characteristics cross taxa. Comparative molecular phylogenetics of vent animals revealed that vent faunas are closely related to those of cold-water seeps in general. In perspective additional interesting discoveries are anticipated particularly with further refined and expanded studies aided by new instrumental technologies.

• Ocean and Polar Research
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• v.25 no.1
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• pp.119-128
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• 2003

Although phoscorites and carbonatites form only a minor proportion of the earth's crustal rocks, these unusual rocks and their intimate relation are of both academic and economic importance. Rare metal (Nb, Zr, Ta) and REEs mineralizations are in close relation with the differentiation of these phoscorite-carbonatite complexes (PCCs). Recent integrated petrological and geochemical data on PCCs in the Kola Alkaline Province, Arctic, indicate that phoscorites and associated carbonatites are differentiated from common 'carbonated silicate patental magma'. Various hypotheses for the genesis of phoscorite-carbonatite complexes have been proposed during the last half-century. A simple magmatic fractionation scheme can not explain the chemical and mineralogical characteristics of phoscorite and conjugate carbonatite. Instead, the hypotheses involving liquid immiscibility and coeval accumulation processes are favored to explain the mineralogical and geochemical characteristics of phoscorite and carbonatite association.

• Ocean and Polar Research
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• v.42 no.1
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• pp.33-47
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• 2020

The bulk and partition geochemistry was studied in two sediment cores collected from the axial valley of the north-central Fonualei Rift and Spreading Center (FRSC), Lau back-arc Basin, southwest Pacific. The sediments consist of mostly volcanic ash, although minor amounts of biogenic and other components were present in some intervals. The major element composition of bulk sediments recalculated to a carbonate-free basis was in good agreement with the magma compositions of the adjacent Tofua Arc and the FRSC, with only significant difference in Mn content. The enrichment of Mn and other associated elements (e.g. Cu, Co, Ni, and P) is attributed to hydrothermal input to the sediments, as evidenced by their significant partitioning in the non-detrital phases according to the partition geochemistry. Hydrogenetic and diagenetic inputs were assessed to be relatively insignificant. Estimated hydrothermal Mn fluxes during the Holocene ranged between 5.0 and 37.1 mg cm^-2 kyr^-1, with the higher values in younger sediments, suggesting enhanced hydrothermal activity. The hydrothermal Mn fluxes comparable to or higher than those reported from other spreading centers with strong hydrothermal activities may indicate the presence of unknown hydrothermal vent sites and/or topographic restriction on the dispersal of hydrothermal plumes in the northern part of the FRSC.

• Economic and Environmental Geology
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• v.45 no.2
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• pp.145-156
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• 2012

Seafloor hydrothermal system occurs along the volcanic mid-ocean ridge, back-arc spreading center, and other submarine volcanic regions. The hydrothermal system is one of the fundamental processes controlling the transfer of energy and matter between crust/mantle and ocean; it forms hydrothermal vents where various deepsea biological communities are inhabited and precipitates metal sulfide deposits. Hydrothermal systems at convergence plate boundaries show diverse geochemical properties due to recycle of subducted material compared to simple systems at mid-ocean ridges. Sulfur isotopes can be used to evaluate such diversity in generation and evolution of hydrothermal system. In this paper, we review the sulfur isotope composition and geochemistry of hydrothermal precipitates sampled from several hydrothermal vents in the divergent plate boundaries in the western Pacific region. Both sulfide and sulfate minerals of the hydrothermal vents in the arc and backarc tectonic settings commonly show low sulfur isotope compositions, which can be attributed to input of magmatic $SO_2$ gas. Diversity in geochemistry of hydrothermal system suggests an active role of magma in the formation of seafloor hydrothermal system.

• Ocean and Polar Research
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• v.23 no.1
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• pp.11-21
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• 2001

K-Ar ages of the altered rocks from the Barton Peninsula are belows; altered tuffaceous andesite from southwestern part is 42 Ma, altered rocks contacted with quartz vein from southern part are 28 and 33 Ma, and advanced argillic altered andesite from northeastern part are 33 and 35 Ma. Those K-Ar ages are 10 My younger than granitic rocks of the Barton Peninsula. Hydothermal alteration of the Barton Peninsula was originated from mixing of magmatic water from parent magma of granitic rocks with meteoric water. The Al content in the hostrock is relatively constant during hydrothermal alteration, on the contrary the Mg content is in proportion to total alkali. The variation of total alkali and Mg contents in hydrothermal alteration indicates that those elements was washed out during hydrothermal alteration. The sequences of hydrothermal alteration of the Barton Peninsula is chloritization of amphiboles, sericitization of feldspars and kaolitization of sericite.

• Economic and Environmental Geology
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• v.51 no.5
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• pp.439-453
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• 2018

The Eocene Gyeongju granitoids in SE Korea are alkali feldspar granite (AGR), biotite granite (BTGR), and hornblende biotite granodiorite (HBGD) along Yangsan fault and Ulsan fault. According to their geochemical characteristics, these granitoids are classified as A-type (AGR) and I-type (BTGR and HBGD) granitoids, and regarded that were derived from same parental magma in upper mantle. The hornblende and biotite of AGR as an interstitial phase indicate that influx of F-rich fluid during the crystallization of AGR magma. AGR is enriched LILE (except Sr and Ba) and LREE that indicate the influences for subduction released fluids. The highest HFSE contents and zircon saturation temperature of AGR among the Eocene Gyeongju granitoids may indicate that it was affected by partial melting rather than magma fractionation. These characteristics may represent that the high F contents of AGR was affected by F-rich fluid derived from the subducted slab and partial melting. It corresponds with the results of the REE modeling and the dehydrated fluid component (Ba/Th) modeling showing that AGR (A-type) was formed by the partial melting of BTGR (I-type) with the continual influx of F-rich fluid derived from the subducted slab.

• Journal of the Korean earth science society
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• v.26 no.1
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• pp.78-92
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• 2005

Petrographical and petrochemical analyses for late Miocene basalts in Goseong-gun area. Gangwon province, were carried out to interpret the characteristics and the origin of magma. The basaltic rocks occurred as plug-dome in the summit of several small mountain and developed columnar jointing with pyroxene-megacryst bearing porphyritic texture. And the basalt contains xenoliths of biotite granite (basement rocks), gabbro (lower crustal origin) and Iherzolite(upper mantle origin). The basalts belong to the alkaline basalt field in TAS diagram and partly belong to picrobasalt and trachybasalt field. On the tectonomagmatic discrimination diagram f3r basalt in the Goseong-gun area. they fall into the fields for the within plate and oceanic island basalt. The characteristics of trace elements and REEs shows that primary magma for the basalt magma would have been derived from partial melting of garnet-peridotite mantle. This late Miocene basalt volcanism is related to the hot spot within the palte.