• The Journal of the Petrological Society of Korea
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• 제28권4호
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• pp.307-317
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• 2019

Petrological studies were performed on the Sanbangsan lava dome, located in the southwest of Jeju Island Volcanic Field. According to the lava ejection method, it is 'an internal primitive form' that is gradually pushed up and expanded by continuous magma injection from the bottom to the top of the vent and it corresponds to the 'low lava dome'. The rocks are partly plotted in the field of benmoreite, but mostly plotted in the field of trachyte of the Cox et al.(1979) classification diagram, and also mainly plotted in the field of trachyte of Le Maitre et al.(2002) and Zr/TiO₂-Nb/Y classification diagram. Therefore, the expression that described the rock of Sanbangsan lava dome as 'trachy-andesite' should be corrected to 'trachyte'. The volcanic rocks that consists in the Sanbangsan lava dome are trachyte containing normative quartz and shows differentiation trend in the range of 59.75-63.46 wt.% SiO₂.

• The Journal of the Petrological Society of Korea
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• 제26권4호
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• pp.341-352
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• 2017

The Jipum Volcanics, occurred in western Yeongdeok, are a stratigraphic unit that is composed of rhyolitic pyroclastic rocks, tuffites, andesitic hyaloclastites, rhyolite lavas, tuffaceous conglomerates and andesite lavas. The SHRIMP U-Pb zircon dating yielded eruption ages of $68.5{\pm}1.6Ma$ from the rhyolitic pyroclastic rocks. Around the time, the unit was generated by dominant rhyolitic volcanisms and locally added by concomitant andesitc volcanisms from another vents. The rhyolitic volcanisms first produced the pyroclastic rocks by phreatomagmatic explosions from rhyolitic magma, later made of the rhyolite lava dome by lava effusions from reopening of the rhyolitc magma at the existing vent. At the time between first and second rhyolitic volcanisms, the tuffites were deposited at a shallow depression in the distal volcanic edifice, and andesitic volcanisms first made of the hyaloclastites by quench fragmentation when hot andesite lavas flew into the depression to contact with cold water. and the Jipum volcano was finally covered with the thin andesitic lavas by lava effusions from another vent.

• The Journal of the Petrological Society of Korea
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• 제14권4호
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• pp.251-263
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• 2005

Modern volcanoes, Laoheishan and Huoshaoshan, have erupted during $1720\~1721$ in the Wudalianchi volcanic group, NE china. They comprise scoria and spatter cones that consist of potassium-rich phono-tephritic pyroclastic deposits and lavas, and include wide lava flow fields. The Laoheishan scoria cone is a polygenetic multiple volcano that overlaps earlier and later edifices with more complicated internal structures produced in greater scale and in earlier time than the Huoshaoshan. There is a funnel-shaped crater in the center of the later edifice of the Laoheishan scoria cone. The Huoshaoshan spatter cone is a monogenetic simple volcano with a central pit crater. The volcanic sequences indicate eruption processes that followed a repeated pattern that progressed through 5 stages of explosive and effusive eruption including lava fountains and Strombolian eruptions in the Laoheishan, and a recognizable pattern of 2 stages that started with Strombolian eruption and progressed through lava effusion in the Huoshaoshan.

• Journal of the Korean association of regional geographers
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• 제18권2호
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• pp.129-140
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• 2012

In order to examine geomorphic characteristics such as form and retreat process of waterfalls in Jeju Island, 26 waterfalls were classified based upon materials forming a fall face. The waterfalls could be categorized into three types such as single unit, multiple units and basal soft-rock based upon the number and type of a lava flow. A block fall, composed of a pile of large blocks, could be added to the typology of waterfalls in Jeju Island. While the single unit fall is distributed in a region of trachyte or trachyandecite, the multiple units fall and basal soft-rock fall are largely developed in a region of basalt or trachybasalt. A retreat process of the single unit fall is an inclination or a replacement, but the basal soft-rock fall shows a parallel retreat. The multiple units fall exhibits three types of a retreat process according to the physical properties of a lava flow. The fall face is generally vertical due to well-developed vertical joints of a lava flow.

• Journal of the Speleological Society of Korea
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• 제28권29호
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• pp.13-20
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• 1992

동굴이란, 땅표면에 뚫려진 자연적인 구멍을 가리킨다. 이와같은 동굴을 보통 자연동굴이라 하는데 이는 그 생성원인에 따라 크게 몇가지로 분류된다. 그 하나는 종유굴이라고 불리우는 석회동굴이다. 종 또는 젖과 같이 매달린 것이 많은 자연굴을 동굴이라고 하여 종유굴이라고 불리어 왔으나 최근에는 이 동굴들이 석회동굴이라고 부르고 있다. 한편 용암동굴 또는 화산동굴이라 부르는 동굴이 있다. 이를테면 폭발되어 흘러나온 용암층 속에서 이루어지기 때문에 용암굴이라 부르거나 화산지층에서 발달된다 하여 화산동굴이라고 부르는 것이다.(중략)

• Proceedings of the Speleological Society Conference
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• 한국동굴학회 2001년도 하계학술발표대회
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• pp.44-55
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• 2001

동굴은 그 생성의 원인이나 형성과정, 그리고 그 형태에 따라 달리 분류된다. 즉 자연동굴과 인공동굴로 대별되기도 하고, 석회동굴, 용암동굴 및 파식굴로 구분 될 수도 있다. 이와 같이 동굴은 그 형성과정 자체로서 많은 주변 학문과 긴밀히 연관되어 있다고 할 수 있다. 우선 석회동굴 및 용암동굴은 석회암 지역과 화산지역에 발달하므로 지질과 지형학 분야에 깊이 관련된다. (중략)

• Journal of the Speleological Society of Korea
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• 제44권45호
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• pp.49-63
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• 1996

암석에는 그 분류기준에 따라 여러 가지 분류방법이 있으나 일반적으로 그 성인에 의한 분류방법이 통용되고 있다. 이 분류방법은 화성암, 퇴적암, 변성암의 세분류로 되고 있다. 이는 1862년에 독일의 콜타(B. von Cotta)가 분류 제창한 것으로 현재까지 전세계에서 널리 사용되고 있는 분류기준이다.(중략)

• Economic and Environmental Geology
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• 제53권5호
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• pp.553-564
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• 2020

Transition between explosive and effusive eruption in Ulleung Island is observed in the Nari Scoria Deposits and Albong Trachyandesite (lava dome) origined by dome-building eruption and may be related to factors such as magma influx, ascent rate and degassing. However, the interpretation of them has not been resolved yet because the interaction between these factors is not complex but also the resulting behaviour during eruption is unpredictable. This paper focuses on the explosive and effusive activity perceived during building the Albong lava dome in Nari caldera. Samples were collected along with time from the scoria deposits and lava dome, linked to eruption stage and style of activity. Textures of groundmass feldspar microlites from these samples are quantitatively analyzed, including measurements of areal number density, mean microlite size, crystal aspect ratio, groundmass crystallinity and crystal size. The microlite textures show that shallow pre- and syn-eruptive magmatic processes acted to govern the changing behaviour during the eruption. Transition between explosive and effusive eruption was driven by the dynamics of magma ascent in the conduit, with degassing and crystallisation acting via feedback mechanisms, resulting in a cycle of effusive and explosive eruption.

• Journal of the Korean association of regional geographers
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• 제12권4호
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• pp.496-507
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• 2006

A hybrid approach integrating both high-resolution and hyperspectral data sets was used to map vegetation cover of a coastal lowland area in the Hawaii Volcanoes National Park. Three common grass species (broomsedge, natal redtop, and pili) and other non-grass species, primarily shrubs, were focused in the study. A 3-step, hybrid approach, combining an unsupervised and a supervised classification schemes, was applied to the vegetation mapping. First, the IKONOS 1-m high-resolution data were classified to create a binary image (vegetated vs. non--vegetated) and converted to 20-meter resolution percent cover vegetation data to match AVIRIS data pixels. Second, the minimum noise fraction (MNF) transformation was used to extract a coherent dimensionality from the original AVIRIS data. Since the grasses and shubs were sparsely distributed and most image pixels were intermingled with lava surfaces, the reflectance component of lava was filtered out with a binary fractional cover analysis assuming that tile total reflectance of a pixel was a linear combination of the reflectance spectra of vegetation and the lava surface. Finally, a supervised approach was used to classify the plant species based on tile maximum likelihood algorithm.

• Journal of the Korean earth science society
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• 제21권5호
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• pp.553-562
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• 2000

Daejeonsa basalt in the Mt. Juwang area is composed of 12 lava flows alternate with 9 peperites, and each lava and peperite has variable thickness. Globular peperites yielded in Daejeonsa basalt are mixed basalt clasts with reddish shale. Based on field description, when lava flows over unconsolidated wet shale or injectes into unconsolidated wet shale, peperites were formed at the contacts between lava and shale. Daejeonsa basalt are massive lava flows with rare vesicules: some vesicules are found in upper part of a flow unit. The basalt has mainly pseudomorphs of olivine as phenocryst, and also plagioclase and clinopyroxene phenocrysts in rocks with higher Mg-number. Matrix is mainly subophitic texture, sometimes showing ophitic and intergranular textures due to different cooling rate. Clinopyroxene is augite(Wo$_{41.6}$En$_{45.1}$Fs$_{13.3}$), and plagioclase is mostly labradorite(An$_{55.0}{\sim}_{67.7}$), but some is andesine(An$_{44.3}$) and bytownite(An$_{74.5}$). Oxide minerals are composed of titanomagnetite and ilmenite.