• Title/Summary/Keyword: Geological history

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Deep-sea Hydrothermal Vents: Ecology and Evolution

  • Won, Yong-Jin
    • 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.

Eruptive History of the Ulleungdo-Dokdo Volcanic Group, the East Sea: a Multi-Scale Approach (동해 울릉도-독도 화산그룹 분화사 다중스케일 연구)

  • Kim, Gi-Bom;Lee, Jae-Hyuk;Ahn, Ho-Jun;Je, Yoon-Hee
    • Journal of the Korean earth science society
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    • v.43 no.1
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    • pp.140-150
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    • 2022
  • This paper focuses on introducing the concept of the multi-scale study on the Ulleungdo-Dokdo Volcanic Group in the East Sea and recent new findings from it. Multi-channel seismic reflection data reveals that the major volcanic activities of the Ulleungdo-Dokdo Volcanic Group took place between 5 and 2.5 Ma, which were propagated from Isabu Tablemount on the eastern end to the Ulleung Island on the western end. The terrestrial Ulleung Island was built via 5 stages, which eventually formed a 3 km-wide caldera, named Nari Caldera, and a volcanic dome, named Albong, within the caldera. The Albong and the unit N-1, the earliest phreatomagmatic explosive phase of the Albong volcano, were generated from a new magma injected into the existing phonolitic body. The generally trachyandesitic bulk rock composition of the pumice in unit N-1 and Albong is attributed to the contamination of the new magma by mafic cumulates at the base of the existing phonolitic chamber. The lines of evidence of a new magma injection point toward that Ulleung Island is an active volcano with a live subvolcanic magma plumbing system.

Occurrence and Deformation of Fe-Ti ores from the Proterozoic Hadong Anorthosites, Korea (원생대 하동회장암체 내 철-티탄 광체의 산상과 변형)

  • Jung, Jae-Sung;Kim, Jong-Sun;Cho, Hyeong-Seong;Song, Cheol-Woo;Son, Moon;Ryoo, Chung-Ryul;Chi, Sei-Jeong;Kim, In-Soo
    • The Journal of the Petrological Society of Korea
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    • v.19 no.1
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    • pp.31-49
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    • 2010
  • Nearly NS-trending Fe-Ti ore bodies intermittently occur in the Hadong anorthosites, south Korea, irrespective of the rock types of the anorthosites. In order to determine their occurrence mode and deformation history, we collected the features of occurrence and geological structures in the field, petrographic features using thin sections of the principal constituent rocks, and geochemical data of ilmenites in the ore body using electron probe microanalysis. Fe-Ti ore bodies examined in this study are divided into two types: dike- and lamina-types. It is steadily supported that the dike-type has intruded into the anorthositic rocks after their emplacement and solidification. And the laminar-type is probably a result of the mylonitization and transposition of the dike-type ore bodies parallel to the shear planes, due to later strong dextral ductile shearing. In the meantime, the Fe-Ti ore bodies have experienced the stronger dextral shearing in the more northern part of the study area, i.e. Cheongryong-ri, Wolhoeng-ri, Jonghwa-ri, and Jayangri and Baekun-ri in ascending order of its strength, together with the less content of $TiO_2$. All ilmenites of the ore bodies have very similar chemical composition, as pure ilmenite of 52~55 wt.% in $TiO_2$ content, irrespective of the occurrence mode and degree of later ductile shearing of the ore bodies. And they didn't experience to exsolve into magnetite. The structural data indicate that the Hadong anorthosites have deformed by NNE-trending folding, intrusion of the Fe-Ti ore bodies, NNW~NNE-trending dextral ductile shearing, NW~NNW-trending sinistral semi-brittle shearing, and intrusion of NNE~NE-trending mafic dykes in descending order of chronology after the formation of foliation of the anorthositic rocks. The foliation is interpreted as a result of the accumulation of crystals that settle out from the magma by the action of gravity.

The History of Volcanic Hazard Map (화산위험지도의 역사)

  • Yun, Sung-Hyo;Chang, Cheolwoo;Ewert, John W.
    • The Journal of the Petrological Society of Korea
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    • v.27 no.1
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    • pp.49-66
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    • 2018
  • Volcano hazard mapping became a focus of scientific inquiry in the 1960s. Dwight Crandell and Don Mullineaux pioneered the geologic history approach with the concept of the past is the key to the future, to hazard mapping. The 1978 publication of the Mount St. Helens hazards assessment and forecast of an eruption in the near future, followed by the large eruption in 1980 demonstrated the utility of volcano hazards assessments and triggered huge growth in this area of volcano science. Numerical models of hazardous processes began to be developed and used for identifying hazardous areas in 1980s and have proliferated since the late 1990s. Model outputs are most useful and accurate when they are constrained by geological knowledge of the volcano. Volcanic Hazard maps can be broadly categorized into those that portray long-term unconditional volcanic hazards-maps showing all areas with some degree of hazard and those that are developed during an unrest or eruption crisis and take into account current monitoring, observation, and forecast information.

Referring to The Stupa of Master ChengGuang, Reconsideration of the History of Buddhist Monks' Octagonal Tempietto Shaped Stupa (승광선사탑(乘廣禪師塔)를 통한 팔각정형(八角亭形) 승탑사(僧塔史)의 재고(再考))

  • Hawong, Moon Ho
    • Journal of architectural history
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    • v.28 no.1
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    • pp.25-34
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    • 2019
  • "Stupa of Buddhist Monk, YeomGeo"(844) is known as the earliest Seon-stupa relic remains in Korean peninsula, from which, during late Silla and ealy Goryeo period, there were more than 30 of stupa was built on such canon. and became the well-known material culture in Seon Buddhism in late Silla period. In $9^{th}$ century, with the JeonDeong(delivering the light of Seon)from Tang to Silla, the culture of "GeonTapIpBi(building the pagoda and erecting stele)" was also moved in. And it was right after the style of monk's stupa had been methodically changed in china, from having the room in stupa for the corpse, named as "QuanShenSheLi", to the lessened stupa that contain the cremated. Analyzing the "Master ChengGuang's stupa"(807)and its stele, it can be found the correspondences of octagonal plan and the subjects of ornamentation to that of Stupas built in Silla, reveals they were made by the same canon. By the document in the stele, surmising the historical cause of alteration in Chan stupa, there was the most famous zen master ShenHui at the time, who has the most important role of making the NanZongChan to get the authenticity in Chan Buddhism. His reliqury was the first ${\acute{s}}ar{\bar{i}}ra$ casket discovered among Chan monks' relics, consequentially it was to influence to Chan cuture and size the monks 'stupa for his ${\acute{s}}ar{\bar{i}}ra$. The stupa of master ChengGuang, by its shape and geological location, is the lost piece in the Puzzle of Chan stupa culture between Silla and Tang.

Mechanical and Electrical Properties of Hydrate-bearing Sediments (하이드레이트 함유 퇴적물의 역학적 성질 및 지구물리 특성)

  • Lee, J.Y.;Francisca, F.;Santamarina, J.C.;Ruppel, C.
    • 한국신재생에너지학회:학술대회논문집
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    • 2007.11a
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    • pp.594-596
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    • 2007
  • Using an oedometer cell instrumented to measure the evolution of electromagnetic properties, small strain stiffness, and temperature, we conducted consolidation tests on four types of sediments. The tested specimens include sediments with different gas hydrate saturation at four stages of loading. The test results show that the electromagnetic and mechanical properties of hydrate-bearing marine sediments are governed by the vertical effective stress, stress history, porosity, hydrate saturation, fabric, ionic concentration of the pore fluid, and temperature. The results also show that permittivity and electrical conductivity data can be combined to estimate hydrate volume fraction in laboratory sediments, methodology that might eventually be extended for estimation of hydrate concentrations in field settings.

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Investigation of possible causes of sinkhole incident at the Zonguldak Coal Basin, Turkey

  • Genis, Melih;Akcin, Hakan;Aydan, Omer;Bacak, Gurkan
    • Geomechanics and Engineering
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    • v.16 no.2
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    • pp.177-185
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    • 2018
  • The subsidence mechanism of ground surface is a complex phenomenon when multiple seam coal mining operations are carried out. Particularly, the coal mining beneath karstic formations causes a very special form of subsidence. The subsidence causes elasto-plastic deformation of the karstic layers and the collapse of cavities leads to dolinization and/or sinkhole formation. In this study, a sinkhole with a depth of 90 m and a width of 25 m formed in Gelik district within the coal-basin of Zonguldak (NW, Turkey) induced by multiple seam coal mining operations in the past has been presented as a case-history together with two-dimensional numerical simulations and InSAR monitoring. The computational results proved that the sinkhole was formed as a result of severe yielding in the close vicinity of the faults in contact with karstic formation due to multiple seam longwall mining at different levels.

Linzhi Native Pig - An Investigation Report on New Genetic Resource of Livestock

  • Chang, H.;Mimachiren, Mimachiren;Li, X.Y.;Ren, Z.J.;Dongwang, Dongwang;Dejiyangzhong, Dejiyangzhong;Chang, G.B.
    • Asian-Australasian Journal of Animal Sciences
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    • v.14 no.9
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    • pp.1203-1208
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    • 2001
  • Linzhi Native Pig is a unique local breed recently discovered in the hinterland of Tibet. Its geological distribution, natural environment and ecological conditions have been explored. Using random sampling in typical colony of classification and standard animal-scientific and biogenetic techniques, we examined its contour features, size and weight, reproductive performances, carcass characters, meat quality, fresh-keeping features and the frequency distribution in the 19 structural gene loci encoding enzymes and proteins; according to folklores and Tibetan, Chinese and English history books, the materials and literature of Tibetan Studies, we have analyzed its origin and affirmed the fact that its products have been consumed as Tibetan medicine resources. Our findings make certain that Linzhi Native Pig holds great potential value in economy and culture.

A Study on the Values Of Dongmag Beach as a Geosite and Increasing its Values (강화도 동막해변의 지질명소로서 가치와 증진 방안에 관한 연구)

  • PARK, Kyeong
    • Journal of The Geomorphological Association of Korea
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    • v.25 no.4
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    • pp.117-129
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    • 2018
  • Dongmag beach area contains diverse geological and geomorphological outcrops which can be used for geotourism purposes. They are as follows; headland with granodiorite with plenty of enclaves and sandy beach, which is fed from Manisan with well-developed sheeting joints composed of granite and granodiorite. Weathered material from the hillside feedsthe one and only sandy beach in Ganghwado Island. Weathered outcrop at the hillside behind beach exposes typical spherical weathering also. Bunori Dondae Fort which was built on top of sea cliff with granodiorite has plenty of history and cultural values commands an extraordinary view of tidal flats and coastal landforms. This geosite with high geodiversity can be used for interpreters who provide balanced views of nature conservation.

Spore-Pollen Specters of Deed Turnn Lake Terrace, Darkhad Depression, Mongolia

  • Punsalpaamuu, G.
    • The Korean Journal of Quaternary Research
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    • v.17 no.2
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    • pp.39-41
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    • 2003
  • Pollen and spores as well as their morphological characteristics are biological stability materials in which contains historical information about vegetation and climate changes. As noted researcher Neishtadt in 1971, the lake and swamp deposits were developed only in Holocene period. The geological history of Darkhad depression which is situated in the Northern end of Mongolia from ancient time become under scientific interest of many researchers. Our investigation was focused on pollen analysis of lake sediment of Darkhad depression which caused bottom of paleolake. In Mongolia the palynology science is beginning to develop since 1990 and in 2000 the laboratory of palynology was established at the department of Biology, State Pedagogical University of Mongolia. Researchers from this laboratory working on pollen morphology of present flora in order to classify plants taxonomy. Another part of our investigation is mellitopalynology, which is studying of pollen grains in a honey. Although, this research has been extending by pollen analysis of sediment and lake deposits in past few years on the basis of high sensitive microscope and modem technology.

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