• Tunnel and Underground Space
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• v.25 no.2
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• pp.199-209
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• 2015

The rebound hardness test using the SilverSchmidt hammer was performed for diorite, granodiorite, and andesite exposed around the King Sejong Station, Barton peninsula. Then, the R-value and uniaxial compressive strength (UCS) of these rocks were estimated from the Q-values which were obtained from the SilverSchmidt hammer. The Q-value of diorite was distributed in the range from 67.0 to 89.5, granodiorite of the range from 57.5 to 89.0, and andesite of the range from 58.0 to 76.5. The average Q-values of diorite, granodiorite, and andesite were 76.0, 72.0, and 67.0, respectively. The converted UCS of diorite was distributed in the range from 118 to 195 MPa, granodiorite of the range from 91 to 193 MPa, and andesite of the range from 92 to 148 MPa. The average UCS of diorite, granodiorite, and andesite were 147, 136, and 117 MPa, respectively. The converted R-value of diorite was distributed in the range from 53.0 to 72.2, granodiorite of the range from 45.4 to 71.8, and andesite of the range from 45.8 to 60.9. The average Q-values of diorite, granodiorite, and andesite were 60.0, 58.0, and 53.0, respectively. The R-value was represented approximately 20% lower than the Q-value. In conclusion, it will be possibile that the R-value and UCS of rocks under the extreme area from the SilverSchmidt Q-value are evaluated.

• 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.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.21 no.2
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• pp.49-57
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• 2016

Even if an external forcing that will drive a climate change is given uniformly over the globe, the corresponding climate change and the feedbacks by the climate system differ by region. Thus the detection of global warming signal has been made on a regional scale as well as on a global average against the internal variabilities and other noises involved in the climate change. The purpose of this study is to estimate a timing of unprecedented climate due to global warming and to analyze the regional differences in the estimated results. For this purpose, unlike previous studies that used climate simulation data, we used an observational dataset to estimate a magnitude of internal variability and a future temperature change. We calculated a linear trend in surface temperature using a historical temperature record from 1880 to 2014 and a magnitude of internal variability as the largest temperature displacement from the linear trend. A timing of unprecedented climate was defined as the first year when a predicted minimum temperature exceeds the maximum temperature record in a historical data and remains as such since then. Presumed that the linear trend and the maximum displacement will be maintained in the future, an unprecedented climate over the land would come within 200 years from now in the western area of Africa, the low latitudes including India and the southern part of Arabian Peninsula in Eurasia, the high latitudes including Greenland and the mid-western part of Canada in North America, the low latitudes including Amazon in South America, the areas surrounding the Ross Sea in Antarctica, and parts of East Asia including Korean Peninsula. On the other hand, an unprecedented climate would come later after 400 years in the high latitudes of Eurasia including the northern Europe, the middle and southern parts of North America including the U.S.A. and Mexico. For the ocean, an unprecedented climate would come within 200 years over the Indian Ocean, the middle latitudes of the North Atlantic and the South Atlantic, parts of the Southern Ocean, the Antarctic Ross Sea, and parts of the Arctic Sea. In the meantime, an unprecedented climate would come even after thousands of years over some other regions of ocean including the eastern tropical Pacific and the North Pacific middle latitudes where an internal variability is large. In summary, spatial pattern in timing of unprecedented climate are different for each continent. For the ocean, it is highly affected by large internal variability except for the high-latitude regions with a significant warming trend. As such, a timing of an unprecedented climate would not be uniform over the globe but considerably different by region. Our results suggest that it is necessary to consider an internal variability as well as a regional warming rate when planning a climate change mitigation and adaption policy.

• 한국해양학회지
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• v.25 no.2
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• pp.74-83
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• 1990

The similarity in Mesozoic geology between the Antarctic Peninsula and South America indicates the possibility that they had situated along the same tectonics line before the separation of southwestern Gondwanaland. The igneous activity around the Antarctic Peninsula, including the South Shetland islands, can be correlated with the South American Cordillera Orogeny due to the subduction of Farallon/Phoenix plate until late Mesozoic. However igneous activity in Tertiary correlates with the tectonics movement accompanying the formations of Drake passage and Scotian sea. The south Shetland islands form a Jurassic-Quaternary miasmatic island arc on the sialic basement of schist and deformed sedimentary rocks. Forming of the South Shetland Islands arc began during the latest Jurassic or earliest Cretaceous from the southwestern part of the archipelago. The igneous activity migrated northeasterly and continued in most areas until late Tertiary. The entire arc-forming period, between late Jurassic and late tertiary times, was characterized by emplacement and eruption of magmas of intermediate between island-arc tholeiite and calc-alkaline types. However, Quaternary volcanic rocks show strong alkaline affinities which corresponds to the switch from compressional to intra: plate tensional tectonics. The rocks of late Cretaceous to Tertiary, mainly found in King George Island, consist of lava of basalt to andesite and intercalated pyroclastic rocks. Some of the volcanic rocks, which ofter called quartz-pyrite lodes'are severely altered and include much content of calcite,silica and pyrite.The stratographic succession of King George Island can be divided into two formation:Fields formation and Hennequin formation.The Fildes formation crops out at the west side of Admiralty Bay n King George Island,while the Hennequin formation at the east side of the bay.These two formtions are thought to be formed contempiranceously.The Fildes formation consists of altered olivine-basalt and basaltic andestie, whereas the Hennequin formation consists of fine-grained hypersthene-augite-andesite.Both formations interclate pyroclastic rocks.

• Ocean and Polar Research
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• v.25 no.4
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• pp.503-518
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• 2003

This study examines the relationship among temperature, wind, and sea level pressure to understand recent warming in the vicinity of the Antarctic Peninsula. To do this, the surface air temperature, NCEP/NCAR reanalysis wind data and sea level pressure data for the period of 40 years are analyzed. The 40-year surface air temperature data in the Antarctic Peninsula reveals relatively the larger warming trends for autumn and winter than other seasons. The variability of the surface air temperature in this region is compared with that of the regional atmospheric circulation. The surface air temperature is positively correlated with frequency of northwesterlies and negatively correlated with frequency of southeasterlies. This relation is more evident in the northern tip of the Antarctic Peninsula for autumn and winter. The trend analysis of wind frequency in the study area shows increasing and decreasing trends in the frequency of northwesterlies and southeasterlies, respectively, in the northwestern part of the Weddell Sea for autumn and winter. And also it is found that these winds are closely related with decreasing of sea level pressure in the southeastern region of the Antarctic Peninsula. Furthermore from the seasonal variation of sea level pressure in this area, it may be presumed that decreasing of sea level pressure in the southeastern region of the Antarctic Peninsula is related with warming in the vicinity of the Antarctic Peninsula for autumn and winter. Therefore it can be explained that recent warming in the vicinity of the Antarctic Peninsula is caused by positive feedback mechanism, that is, the process that warming in the vicinity of the Antarctic Peninsula can lead to the decrease of sea level pressure in the southeastern region of the Antarctic Peninsula and these pressure decrease in turn lead to the variation of wind direction in northwestern part of Weddell Sea, again the variation of wind direction enhances the warming in the Antarctic Peninsula.

• Journal of the Mineralogical Society of Korea
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• v.31 no.1
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• pp.1-12
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• 2018

A gravity core (RS14-C2) was collected at site RS14-C2 in the continental slope to the east of Pennell-Isellin Bank of the Ross Sea (Antarctica) during PNRA XXIX (Rosslope II Project) Expedition. In order to trace the sediment source, magnetic susceptibility (MS), sand fraction, and clay mineral compositions were analyzed, and AMS $^{14}C$ ages were dated. Core sediments consist mostly of hemipelagic sandy clay or silty clay including ice-rafted debris (IRD). AMS $^{14}C$ age of core-top indicates the modern and Holocene sediments. Based on AMS $^{14}C$ dating, sediment color, MS and sand fraction, core sediments are divided into interglacial and glacial intervals. The interglacial brown sediments are characterized by low MS and sand fraction, whereas the glacial gray sediments are characterized by high MS and sand fraction. Among clay mineral compositions of core sediments, illite is highest (61.8~76.7%), and chlorite (15.7~21.3%), kaolinite (3.6~15.4%), and smectite (0.9~5.1%) are in decreasing order, and these compositions are also divided into the interglacial and glacial/deglacial intervals. During the glacial period, the high content of illite and chlorite indicate sediment supply from the bedrocks of Transantarctic Mountains under the Ross Ice Sheet. In contrast, because of decreasing supply of illite and chlorite by the glacial retreat, smectite and kaolinite contents increased relatively during the interglacial period. During the interglacial period, smectite may be transported additionally by the northeastward flowing surface current from the coast of Victoria Land in the western Ross Sea. Kaolinite may be also supplied to the continental slope by the Antarctic Slope Current from the kaolin-rich metasedimentary rock outcropped on the Edward VII Peninsula.

• Korean Journal of Remote Sensing
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• v.35 no.6_1
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• pp.933-944
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• 2019

This study analyzes the tide deformation of land boundary regions on the east (Region A) and west (Region B) sides of the Ross Ice Shelf in Antarctica using Double-Differential Interferometric Synthetic Aperture Radar (DDInSAR). A total of seven Sentinel-1A SAR images acquired in 2015-2016 were used to estimate the accuracy of tide prediction model and Young's modulus of ice shelf. First, we compared the Ross Sea Height-based Tidal Inverse (Ross_Inv) model, which is a representative tide prediction model for the Antarctic Ross Sea, with the tide deformation of the ice shelf extracted from the DDInSAR image. The accuracy was analyzed as 3.86 cm in the east region of Ross Ice Shelf and it was confirmed that the inverse barometric pressure effect must be corrected in the tide model. However, in the east, it is confirmed that the tide model may be inaccurate because a large error occurs even after correction of the atmospheric effect. In addition, the Young's modulus of the ice was calculated on the basis of the one-dimensional elastic beam model showing the correlation between the width of the hinge zone where the tide strain occurs and the ice thickness. For this purpose, the grounding line is defined as the line where the displacement caused by the tide appears in the DDInSAR image, and the hinge line is defined as the line to have the local maximum/minimum deformation, and the hinge zone as the area between the two lines. According to the one-dimensional elastic beam model assuming a semi-infinite plane, the width of the hinge region is directly proportional to the 0.75 power of the ice thickness. The width of the hinge zone was measured in the area where the ground line and the hinge line were close to the straight line shown in DDInSAR. The linear regression analysis with the 0.75 power of BEDMAP2 ice thickness estimated the Young's modulus of 1.77±0.73 GPa in the east and west of the Ross Ice Shelf. In this way, more accurate Young's modulus can be estimated by accumulating Sentinel-1 images in the future.

• Journal of the Mineralogical Society of Korea
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• v.32 no.3
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• pp.163-172
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• 2019

A long core (RS15-LC48) was collected at a site in the continental rise between the Southern Ocean and the Ross Sea (Antarctica) during the 2015 Ross Sea Expedition. The mineralogical characteristics and the origin of clay minerals in marine sediments deposited during the Quaternary in the Ross Sea were determined by analyzing sedimentary facies, variations in grain size, sand fraction, mineralogy, clay mineral composition, illite crystallinity, and illite chemical index. Core sediments consisted mostly of sandy clay, silty clay, or ice rafted debris (IRD) and were divided into four sedimentary facies (units 1-4). The variations in grain size distribution and sand content with depth were very similar to the variations in magnetic susceptibility. Various minerals such as smectite, chlorite, illite, kaolinite, quartz, and plagioclase were detected throughout the core. The average clay mineral composition was dominated by illite (52.7 %) and smectite (27.7 %), with less abundant clay minerals of chlorite (11.0 %) and kaolinite (8.6 %). The IC and illite chemical index showed strong correlation trends with depth. The increase in illite and chlorite content during the glacial period, together with the IC and chemical index values, suggest that sediments were transported from the bedrocks of the Transantarctic Mountains. During the interglacial period, smectite may have been supplied by the surface current from Victoria Land, in the western Ross Sea. High values for IC and the illite chemical index also indicate relatively warm climate conditions during that period.

• Journal of the Mineralogical Society of Korea
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• v.32 no.3
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• pp.173-184
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• 2019

Variations in grain size distribution and clay mineral assemblage are closely related to the sedimentary facies that reflect depositional conditions during the glacial and interglacial periods. Gravity cores BS17-GC15 and BS17-GC04 were collected from the continental shelf and rise in the eastern Bellingshausen Sea during a cruise of the ANA07D Cruise Expedition by the Korea Polar Research Institute in 2017. Core sediments in BS17-GC15 consisted of subglacial diamicton, gravelly muddy sand, and bioturbated diatom-bearing mud from the bottom to the top sediments. Core sediments in BS17-GC04 comprised silty mud with turbidites, brownish structureless mud, laminated mud, and brownish silty bioturbated diatom-bearing mud from the bottom to the top sediments. The clay mineral assemblages in the two core sediments mainly consisted of smectite, chlorite, illite, and kaolinite. The clay mineral contents in core GC15 showed a variation in illite from 28.4 % to 44.5 % in down-core changes. Smectite contents varied from 31.1 % in the glacial period to 20 % in the deglacial period and 25.1 % in the interglacial period. Chlorite and kaolinite contents decreased from 40.5 % in the glacial period to 30.3 % in the interglacial period. The high contents of illite and chlorite indicated a terrigenous detritus supply from the bedrocks of the Antarctic Peninsula. Core GC04 from the continental rise showed a decrease in the average smectite content from 47.2 % in the glacial period to 20.6 % in the interglacial period, while the illite contents increased from the 21.3 % to 43.2 % from the glacial to the interglacial period. The high smectite contents in core GC04 during the glacial period may be supplied from Peter I Island, which has a known smectite-rich sediment contributed by Antarctic Circumpolar Currents. Conversely, the decrease in smectite and increase in chlorite and illite contents during the interglacial period was likely caused by a higher supply of chlorite- and illite-enriched sediment from the eastern Bellingshausen Sea shelf by the southwestward flowing contour current.

• Ocean and Polar Research
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• v.25 no.2
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• pp.201-211
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• 2003

Bottom simulating reflectors (BSR), representing the base of the gas hydrate stability field, are widespread on the South Shetland continental margin (SSM), Antarctic Peninsula. With the phase diagram fur the gas hydrate stability field, heat flow can be derived from the BSR depth beneath the seafloor determined on multichannel seismic profiles. The heat flow values in the study area range from $50mW/m^2$ to $85mW/m^2$, averaging to $65mW/m^2$. Small deviation from the average heat flow values suggests that heat flow regime of the study area is relatively stable. The landward decrease of heat flow from the South Shetland Trench to the continental shelf would be attributed to the landward thickening of the accretionary prism and the upward advection of heat associated with fluid expulsion. The continental slope 1500m to 3000m deep, where BSRs are most distinguished in the SSM, shows relatively large variation of heat flow possibly due to complex tectonic activities in the study area. The local high heat flow anomalies observed along the slope may be caused by heat transport mechanisms along a NW-SE trending large-scale fault.