• Economic and Environmental Geology
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• v.47 no.1
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• pp.17-27
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• 2014

We investigated space-time patterns of Quaternary fault activity of the Yangsan fault zone using ESR ages in the Samnam-myeon region, Ulsan, Korea. Some of fault gouge zones consist of well-defined bands which added to the older gouge band, indicative of reactivation. During addition of new bands, the older gouge band was inactive, which represents the type I faulting mode. ESR analyses of each band of the gouge zone allow us to construct history of fault movement. The entire fault gouge zones were reactivated by type III faulting mode giving us ESR ages of the lastest reactivation. ESR dates show temporal clustering into active and inactive periods analogous to historic and paleoseismic fault activities. ESR ages and dates of fault movements indicate migration of fault activities along the Yangsan Fault Zone. Segments of the Quaternary faults in the study area are branched in the south of Sangcheon site. The earliest record of activity in segmented faults is recorded from the western segment to the northern segment. Before 750~850 ka ago, the fault gouge zone from the western segment to the northern segment were active. At 750~850 ka ago, the fault gouge zone from the eastern segment to the northern segment were active. During 630~660 ka and 480~540 ka only the northern segment was active. After 340 ka ago, the fault gouge zone from the western segment to the northern segment were active again.

• Economic and Environmental Geology
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• v.56 no.3
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• pp.293-300
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• 2023

The Shape Preferred Orientation (SPO) method has been used to analyze the orientation of fault motion, which is utilized as basic data for fault kinematics studies. The rigid grains, which as quartz, feldspar, and rock fragments, in the fault gouge are arranged in the P-shear direction through rigid body rotation by a given shear stress. Using this characteristic, the fault motion can be estimated from the SPO inversely. Recently, a method for securing precision and reliability by measuring 3D-SPO using X-ray CT images and examining the shape of a large number of particles in a short time has been developed. As a result, the SPO method analyzes the orientation of thousands to tens of thousands of particles at high speed, suggests the direction of fault motion, and provides easy accessibility and reliable data. In addition, the shape information and orientation distribution data of particles, which are by-products obtained in the SPO analysis process, are expected to be used as basic data for conducting various studies such as the local deformation of fault rocks and the fault generation mechanism.

• The Journal of Engineering Geology
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• v.8 no.2
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• pp.175-188
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• 1998

This paper describes the internal structures and K-Ar ages of fault gouges collected from the Dongnae fault zone. This fault zone is internally zoned and occurs in the multiple fault cores. A fault core consists of thin gouge and narrow cataclastic zones that are bounded by a much thicker damage zone. Intensity of deformation and alteration increases from damage zone through cataclastic zone to gouge zone. It is thought that cataclasis of brittle deformation was the dominant strain-accomodation mechanism in the early stage of deformation to form the gouge zone and that crushed materials in the regions of maximum localization of fault slip subsequently moved by cataclastic flow. Deformation mechanism drastically changed from brittle processes to fluid-assisted flow along the gouge zone as the high porosity and permeability of pulverzied materials during faulting facilitated the influx of the hydrothermal fluids. Subsequently, the fluids reacted with gouge materials to form clay minerals. Fracturing and alteration could have repeatedly taken place in the gouge zone by elevated fluid pressures generated from the reduction of pore volume due to the formation of clay minerals and precipitation of other materials. XRD analysis revealed that the most common clay minerals of the gouge zones are illite and smectite with minor zeolite and kaolinite. Most of illites are composed of 1Md polytype, indicating the products of hydrothermal alteration. The major activities of the Dongnae fault can be divided into two periods based upon K-Ar age data of the fault gouges : 51.4∼57.5Ma and 40.3∼43.6Ma. Judging from the enviromental condition of clay mineral formation, it is inferred that the hydrothermal alteration of older period occured at higher temperature than that of younger period.

• Journal of the Mineralogical Society of Korea
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• v.25 no.1
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• pp.23-36
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• 2012

Morphological and mineralogical characteristics of laumontite and adularia in the breccia zone in a fault, Yangbuk-myeon, Gyeongju, Korea suggest that they formed by reaction with hydrothermal alteration related to fault activity. Laumontite commonly occurring in the breccia zone is related to the presence of hydrothermal fluids bearing alkaline elements in the zone. Laumonite is characterized by elongated columnar form with aspect ratio varying 5~10. Laumontite and adularia whose characteristic euhedral forms are indicative of the latest product formed as rapid precipitation from fluids or replacements of Ca-plagioclase. Hydrothermal fluids reacted with intensively fractured granite, typical with high permeability, leached alkaline elements such as Ca, K, allowing laumontite and adularia to be precipitated under neutral to weak alkaline conditions. It is noteworthy that the formation process and genesis of low temperature minerals such as laumontite and adularia are very similar to those formed by wallrock alteration or hydrothermal alteration that occurred in epithermal deposits. Taking into account its characteristic morphology and chemistry, authigenic K-feldspar that commonly forms at low temperature in many fault zones must be adularia.

• Journal of the Speleological Society of Korea
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• v.4 no.5
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• pp.14-26
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• 1979

최근에 와서 석회암 지형에 대한 조사연구는 활발히 진행되고 있다. 특히 석회동굴을 중심으로 하여 관광 학술면에서 그 활동 방향이 진행되고 있으나 이와같은 동굴의 형성도 석회암지형의 발달과 관련하여 그 형성이 규명되어야 하고 동굴의 형성과 지하수면과의 관계 종유동 형성의 시간적 길이, 절리, 단층 등이 동굴형태와의 관계도 종합적인 석회암지형을 연구함으로써 지형학적, 지질학적 제문제가 해결되리라 생각된다.(중략)

• The Journal of the Petrological Society of Korea
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• v.25 no.3
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• pp.195-209
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• 2016

The understanding of geometric complexity of strike-slip Fault system can be an important factor to control fault reactivation and surface rupture propagation under the regional stress regime. The Kumamoto earthquake was caused by dextral reactivation of the Futagawa-Hinagu Fault system under the E-W maximum horizontal principal stress. The earthquakes are a set of earthquakes, including a foreshock earthquake with a magnitude 6.2 at the northern tip of the Hinagu Fault on April 14, 2016 and a magnitude 7.0 mainshock which generated at the intersection of the two faults on April 16, 2016. The hypocenters of the main shock and aftershocks have moved toward NE direction along the Futagawa Fault and terminated at Mt. Aso area. The intersection of the two faults has a similar configuration of ${\lambda}$-fault. The geometries and kinematics, of these faults were comparable to the Yansan-Ulsan Fault system in SE Korea. But slip rate is little different. The results of age dating show that the Quaternary faults distributed along the northern segment of the Yangsan Fault and the Ulsan Fault are younger than those along the southern segment of the Yansan Fault. This result is well consistent with the previous study with Column stress model. Thus, the seismic activity along the middle and northern segment of the Yangsan Fault and the Ulsan Fault might be relatively active compared with that of the southern segment of the Yangsan Fault. Therefore, more detailed seismic hazard and paleoseismic studies should be carried out in this area.

• 한국지구물리탐사학회:학술대회논문집
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• 2004.06a
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• pp.176-181
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• 2004

남${\cdot}$북 Bismarck 판은 호주판과 태평양 판 사이의 복잡한 판구조를 보이는 지역에 위치한다. 남${\cdot}$북 Bismarck 판 내부에서는 판구조 활동이 활발하게 일어나 지진의 발생빈도가 높고 활성 및 비활성화산이 많이 존재한다. 한국해양연구원은 Bismarck 해의 서부지역과 동 Manus 분지에서 판 경계부의 구조 및 열수구조의 밝히기 위하여 탄성파 탐사를 수행하였다. 탐사결과에 의하면 남${\cdot}$북 Bismarck 판의 경계부에는 주향이동단층대가 발달되어 있으며 이는 판의 경계를 나타내고 있다. PACMANUS 열수하부에는 돔 형태의 구조가 존재하며 이는 마그마 또는 이의 분화과정에서 형성된 지질학적인 구조로 추정된다.

• Economic and Environmental Geology
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• v.52 no.5
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• pp.395-407
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• 2019

The duplex system has been considered as an important slip-transfer mechanism to evaluate the evolution of orogenic belts. Duplexes are generally found in the hinterland portion of fold-thrust belts and accommodate large amounts of total shortening. Thus, understanding its geometric and kinematic evolution can give information to evaluate the evolution of the entire orogenic belt. Duplexes are recognized as closed-loop thrust traces on map view, indicating higher connectivity than imbricate fans. As originally defined, a duplex is an array of thrust horses which are surrounded by thrust faults including the floor and roof thrusts, and imbricate faults between them. Duplexes can accommodate regional layer-parallel shortening and transfer slip from a floor thrust to a roof thrust. However, an imbricate fault is not the only mean for layer-parallel shortening (LPS) and displacement transfer within duplexes. LPS cleavages and detachment folds can also play the same role. From this aspect, a duplex can be divided into three types; 1) fault duplex, 2) cleavage duplex and 3) fold duplex. Fault duplex can further be subdivided into the Boyer-type duplex, which was firstly designed duplex system in the 1980s that widely applied most of the major fold-thrust belts in the world, and connecting splay duplex, which has different time order in the emplacement of horses from those of the Boyer-type. On the contrary, the cleavage and fold duplexes are newly defined types based on some selected examples. In the Korean Peninsula, the Yeongwol area, the western part of the Taebaeksan Zone of the Okcheon Belt, gives an excellent natural laboratory to study the structural geometry and kinematics of the closed-loops by thrust fault traces in terms of a duplex system. In the previous study, the Yeongwol thrust system was interpreted by alternative duplex models; a Boyer-type hinterland-dipping duplex vs. a combination of major imbricate thrusts and their connecting splays. Although the high angled beds and thrusts as well as different stratigraphic packages within the horses of the Yeongwol duplex system may prefer the later complicate model, currently, we cannot choose one simple answer between the models because of the lack of direct field evidence and time information. Therefore, further researches on the structural field investigations and geochronological analyses in the Yeongwol and adjacent areas should be carried out to test the possibility of applying the fold and cleavage duplex models to the Yeongwol thrust system, and it will eventually provide clues to solve the enigma of formation and its evolution of the Okcheon Belt.

• Journal of Chest Surgery
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• v.41 no.1
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• pp.137-140
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• 2008

Puimonary Langerhans cell histiocytosis is very rare, especially when accompanied by active pulmonary. tuberculosis. A patient was hospitalized due to excessive dyspnea and she was diagnosed with active pulmonary tuberculosis by a sputum AFB smear. The HRCT taken after hospitalization showed multiple micronodules and tiny cysts. An open lung biopsy confirmed the coexistence of pulmonary Langerhans cell histiocytosis.

• Geophysics and Geophysical Exploration
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• v.13 no.4
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• pp.407-415
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• 2010

MT soundings were carried out in 2008, in northern Victoria, Australia, as a continuing collaboration research of 2007 between Republic of Korea, Australia, and Japan. The main purpose of this research is to investigate electrical conductivity structure and thus help understanding of tectonic structure in central Victoria, which is believed to be closely linked to mineralization and magmatic processes of this region. The survey area is located in western Lachlan Fold Belts, which is the part of Tasman Fold Belts in southeastern Australia. An MT profile of 2008 is almost parallel to the one of 2007 and approximately 50 km away. The 2D inversion result of MT data also shows that the position of conductivity discontinuity near surface are well matched with the positions of major faults, such as Avoca Fault, which is the structural boundary between Stawell and Bendigo Zones, and Heathcote Fault Zone, which marks the boundary between Bendigo and Melbourne Zones. It is also confirmed from resistivity image that internal faults in Bendigo Zone are in listric form, which is implied to be formed by structural shortening during compressional orogenic activity in Silurian.