• Proceedings of the Microbiological Society of Korea Conference
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• 2007.05a
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• pp.79-79
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• 2007

• 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.

• Economic and Environmental Geology
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• v.47 no.4
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• pp.395-404
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• 2014

We conducted the geophysical survey of possible hydrothermal vent sites at 2009, in the Lau Basin, the south western Pacific and analyzed the magnetic characteristics of TA19-1 and TA19-2 seamounts. TA19-1 is a cone-shaped seamount with a caldera summit. TA19-2 seamount is bigger and shows more complicated topography than TA19-1 seamount. TA19-2 has a large caldera, a summit in the west side of the caldera and several crests. Simple dipole anomalies with a high over the north and a low over the south occur in TA19-1 seamount. High magnetic anomalies are located in the northern flank and the summit of TA19-2 seamount and low anomalies around the summit and the caldera. The results of bathymetry and magnetic data suggest that TA19-2 seamount might have more complicated magmatic process than TA19-1. Low magnetization zones are located over the summit, the calderas and the caldera rims. The magnetization lows indicate that submarine hydrothermal vents, along faults and fracture zones, could have caused an alteration of magnetic minerals. The magnetization highs over the summit and the calderas might have been related with later magmatisms like volcanic sills, intrusions.

• Journal of Ocean Engineering and Technology
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• v.31 no.1
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• pp.69-79
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• 2017

This paper presents the operations of a multi-beam echo sounder (MBES) installed on the deep-sea remotely operated vehicle (ROV) Hemire. Hemire explored hydrothermal vents in the Forecast volcano located near the Mariana Trench in March of in 2006. During these explorations, we acquired profiling points on the routes of the vehicle using the MBES. Information on the position, depth, and attitude of the ROV are essential to obtain higher accuracy for the profiling quality. However, the MBES installed on Hemire does not have its own position and depth sensors. Although it has attitude sensors for roll, pitch, and heading, the specifications of these sensors were not clear. Therefore, we had to merge the high-performance sensor data for the motion and position obtained from Hemire into the profiling data of the MBES. Then, we could properly convert the profiling points with respect to the Earth-fixed coordinates. This paper describes the integration of the MBES with Hemire, as well as the coordinate conversion between them. Bathymetric maps near the summit of the Forecast volcano were successfully collected through these processes. A comparison between the bathymetric maps from the MBES and those from the Onnuri Research Vessel, the mother ship of the ROV Hemire for these explorations, is also presented.

• Journal of Ocean Engineering and Technology
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• v.30 no.5
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• pp.389-399
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• 2016

This paper presents the explorations of hydrothermal vents located in the Marina Arc and Back Arc Basin using the deep-sea ROV Hemire. These explorations were conducted by KRISO and KIOST to demonstrate the capability of Hemire in various applications for deep-sea scientific research. The missions included the following: (1) to search the reported vents, (2) conduct visual inspections, (3) deploy/recover a sediment trap and bait traps, (4) sample sediment/water/rock, (5) measure the magnetic field at the vent site, and (6) acquire a detailed map using multi-beam sonar near the bottom. We installed three HD cameras for precise visual inspection, a high-temperature thermometer, a three-component magnetometer, and a multi-beam sonar to acquire details of the bottom contour or identify vents in the survey area. The explorations were performed in an expedition from March 23 to April 5, 2016, and the missions were successfully completed. This paper discusses the operational process, navigation, and control of Hemire, as well as the exploration results.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.4
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• pp.363-373
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• 2000

To understand and investigate chemical characteristics of thermal environment in the southwestern Paciflc, we have measured hydrological and chemical parameters such as temperature, salinity, transparency, pH, nutrients and hydrogen sulfide (H$_2$S). Samples were collected with CTD-casting at 12 station, in Manus Basin including PACMANUS, DESMOS and Susu Knolls, Hydrothermal systems consist of circulation zones where seawater interacts with rock, thereby changing chemical and physical characteristics of both the seawater and the rock. The altered seawater, called hydrothermal fluid, is injected back into the ocean from the hydrothermal vent fields and forms hydrothermal plumes. Consequently, we detected hydrothermal plume with transparency and sulfide anomalies at PACMANUS and Susu Knolls. Sulfide, as geochemical tracer of hydrothermal plume, ranged 0-3.31 ${\mu}$M, and averaged 0.63 ${\mu}$M in the study area. The height, flux and activity of the plume are affected by circulations in the deep water and the spread of plume follows along the isopycnal surface. Therefore the observed H$_2$S anomaly can provide important clue for the source location and it appears that the targestsource in the PACMANUS is aligned in the north-south direction.

• Ocean and Polar Research
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• v.22 no.1
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• pp.1-13
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• 2000

Chemoautotrophic symbiotic bacteria of organisms inhabiting the hydrothermal vent and cold seep communities in the deep-sea were histologically examined using a transmission electron microscopy on symbionts of Calyptogena sp. A from the site east off Miyako (water depth at 1,700m), Calyptogena sp. B from the Calyptogena Site, vestimentiferan tube worm Lamellibrachia sp. A from Sagami Bay Lamellibrachia sp. B from Calyptogena Site of the Iheya Ridge, pogonophoran tube worms from Sagami Bay and Calyptogena Site of the Iheya Ridge, Bathymodiolus spp. from Sagami Bay, the Iheya Ridge and the North Fiji Basin. Based on the morphological microscopic observations, two species of Calyptogena from Miyako and the Iheya Ridge, two species of vestimentiferan tube worms from Sagami Bay and the Iheya Ridge, and pogonophoran tube worms from Sagami Bay and the Iheya Ridge observed to host sulfur-oxidizing symbiotic bacteria. The occurrence of chemosynthetic symbionts in these organisms was expected beforehand based on the ecological observations of their habitats. Other members of these groups from the world oceans, and the recent advances in the symbiosis at vents and seeps were reviewed.

• The Korean Journal of Food And Nutrition
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• v.7 no.4
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• pp.259-266
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• 1994

The hyperthermophilic archaebacterium Thermococcus profundus Isolated from a deep-sea hydrothermal vent system, produced several amylolytic enzymes such as extracellular amylase and pullulanase, intracellular a-1,4-91ucosidase in respone to the presence of complex carbohydrates In the growth medium. This strain showed high activities on 0.5% maltose than on complex carbohydrates One of the amylases was partially purified by ammonium sulfate precipitation, DEAE-Toyopearl chromatography. The amylase exhibited maximal activity at pH 5.5 and 80$^{\circ}C$, and was stable in the range of pH 5.5 to 9.5 and up to 80$^{\circ}C$ for 30 min. The enzyme activity was no dependence on Ca2+ and not inhibited by detergents. The amylase hydrolyzed soluble starch, amylose, amylopectin and glycogen to produce maltose and maltotriose with trace amounts of glucose, but not pullulan and ${\alpha}$-, ${\beta}$-, ${\gamma}$-cyclodextrin. Malto-oligosaccharides ranging from maltotetraose to maltoheptaose were hydrolyzed in an endo fashion.

• Animal Systematics, Evolution and Diversity
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• v.39 no.1
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• pp.47-52
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• 2023

Thermopolynoe Miura, 1994 is a monotypic genus in Lepidonotopodinae that comprises species endemic to chemosynthesis-based ecosystems. Here, we examined T. branchiata collected from the hydrothermal vents in the North Fiji Basin. For the first time in Thermopolynoe, we report sexual dimorphism detecting nephridial papillae on segments 11-13 in males, additionally describe the morphology on elytra with round to conical microtubercles on the surface, and distinguish presence of small neuropodial lobes on segments 3-26. We also revised couple of errors and ambiguities in the original description: incongruence between the description and figure and existence of individual variation in ratio of tentacular cirri and palps. In addition, three COI sequences of T. branchiata specimens from the North Fiji Basin were newly obtained and sequences divergence with other Lepidonotopodinae species were determined. These results would contribute to the taxonomy of polynoids in a chemosynthesis-based ecosystem.

• Journal of the Mineralogical Society of Korea
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• v.25 no.4
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• pp.233-247
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• 2012

We have researched the distribution and characteristics of seafloor hydrothermal deposits for the development of economic mineral deposits in the Lau Basin, Tonga since 2009. In this study, we interpreted hydrothermal alteration around TA 26 seamounts of the Tofua volcanic arc using X-ray diffraction analysis for bulk sample and preferred-oriented specimen of clay fraction. We used 2 core samples and several surface samples. Plagioclase and quartz are dominant mineral in the basement rock, whereas kaolin mineral and smectite are superior in marine surface sediments. Especially sulfate and sulfide minerals such as gypsum, barite, sphalerite, and pyrite are predominant in the vent sediments. When we compare the mineral composition between basement rock and sea surface sediments, argillic alteration zone composed of kaolin mineral and smectite could be produced by hydrothermal fluids. Based on the downcore variation of mineral assemblages, most portion of MC08H-06 core could be interpreted as argillic alteration zone composed of kaolin mineral and smectite except top 2 cm area. Various sulfate or sulfide minerals and argillic alteration zone suggest a high probability of massive sulfide deposits in the seafloor of the TA 26 seamount.