• Proceedings of the KSEEG Conference
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• 2001.04a
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• pp.247-248
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• 2001

• Geomechanics and Engineering
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• v.22 no.4
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• pp.349-359
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• 2020

Quantification of the influence of the fracture of thick magmatic rock (TMR) on the behavior of its overlying strata is a prerequisite to the understanding of the deformation behavior of the earth's surface in deep mining. A three-dimensional numerical model of a special geological mining condition of overlying TMR was developed to investigate the overburden movement and fracture law, and compare the influence of the occurrence horizon of TMR. The research results show that the movement of overlying rock was greatly affected by the TMR. Before the fracture of TMR, the TMR had shielding and controlling effects on the overlying strata, the maximum vertical and horizontal displacement values of overlying strata were 0.68 m and 0.062 m. After the fracture, the vertical and horizontal displacements suddenly increased to 3.06 m and 0.105 m, with an increase of 350% and 69.4%, respectively, and the higher the occurrence of TMR, the smaller the settlement of the overlying strata, but the wider the settlement span, the smaller the corresponding deformation value of the basin edge (the more difficult the surface to crack). These results are of tremendous importance for the control of rock strata and the revealing of surface deformation mechanism under TMR mining conditions in mines.

• Journal of the Mineralogical Society of Korea
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• v.4 no.2
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• pp.69-89
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• 1991

The anorthositic rocks and the many other plutons which are of different varieties and age were distributed in the northern extremity of the distributed areas of H-S anorthositic rocks. The purpose of this study was to find plutons which had comagmatic relationships, and to make clear the magmatic process of anorthositic magma. The plutons were classified, and the petrological and the geochemical characteristics of the plutons were compared and researched in this study. And, because, like anorthosite, the rocks which intrude in the deep crust accompany assimilation, an AFC model calculation was performed to make the differentiation process of the anorthositic rocks clear. The plutons in this area were classified into three groups, and the three groups were composed of the Precambrian anorthositic rocks and related rocks, the Jurassic gabbro, and the plutons of undnown age. The anorthositic magma was differentiated from the anorthositic rocks through the tonalite to the alkali-feldspar granite, and it was differentiated under K, Mg, Fe free/lack condition. It was found from the result of AFC model that the anorthositic rocks were differentiated by fractional crystallization, but they were assimilated with wall-rocks, and the assimilation was performed at the rate of r$\leq$0.1. The plutons which intruded the anorthositic rocks subsequently consisted of the gabbro, the megacrystic granite, the fine-grained granite, and the gneissose granite. But they were formed by the repeated intrusion of magma, which may, or may not, be of the same origin. According to the result of the RCF model, these plutons were differentiated by simple fractional crystallization, and they were assimilated relatively less than the anorthositic rocks.

• Geophysics and Geophysical Exploration
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• v.6 no.1
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• pp.40-52
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• 2003

Despite the various opening models of the southwestern part of the East Sea (Japan Sea) between the Korean Peninsula and the Japan Arc, the continental margin of the Korean Peninsula remains unknown in crustal structure. As a result, continental rifting and subsequent seafloor spreading processes to explain the opening of the East Sea have not been adequately addressed. We investigated crustal and sedimentary velocity structures across the Korean margin into the adjacent Ulleung Basin from multichannel seismic reflection and ocean bottom seismometer data. The Ulleung Basin shows crustal velocity structure typical of oceanic although its crustal thickness of about 10 km is greater than normal. The continental margin documents rapid transition from continental to oceanic crust, exhibiting a remarkable decrease in crustal thickness accompanied by shallowing of Moho over a distance of about 50 km. The crustal model of the margin is characterized by a high-velocity (up to 7.4 km/s) lower crustal (HVLC) layer that is thicker than 10 km under the slope base and pinches out seawards. The HVLC layer is interpreted as magmatic underplating emplaced during continental rifting In response to high upper mantle temperature. The acoustic basement of the slope base shows an igneous stratigraphy developed by massive volcanic eruption. These features suggest that the evolution of the Korean margin can be explained by the processes occurring at volcanic rifted margins. Global earthquake tomography supports our interpretation by defining the abnormally hot upper mantle across the Korean margin and in the Ulleung Basin.

• Journal of the Korean Geophysical Society
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• v.10 no.1
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• pp.13-25
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• 2007

We investigated the undulation of Moho depth and the crustal structure of the continental margin in the East Sea along the Korea Peninsula from inversion and modelling using potential data and previous seismic results. Free-air gravity anomalies generally reflect topography effect. Bouguer gravity anomalies increase toward the Ulleung Basin, indicating that Moho depth is shallower under the Ulleung Basin. Positive magnetic anomalies exist along the continental margin and decrease toward the Ulleung Basin. In analytic signal, the small anomaly in the Hupo Bank infers that the Hupo Bank is uplifted by igneous intrusion and the strong anomaly on the continental slope denotes existence of SDR(seaward dipping reflectors), which are in accordance with the location of SDR detected in previous seismic studies. The inversion result of Bouguer gravity anomaly and the 2-dimensional gravity modelling indicate that the undulation of Moho depth shallows from the continental shelf toward the Ulleung Basin. This is in good agreement with the Moho depth calculated by the previous seismic velocity model using ocean bottom seismometer(OBS). The 2-dimensional gravity modelling infers magmatic underplating zone under the lower continental crust on the continental margin of the East Sea, indicating the possible rifiting of the continental margin.

• The Journal of the Petrological Society of Korea
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• v.6 no.2
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• pp.77-85
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• 1997

The Early Proterozoic reworked rock association occurs within the Preacmbrian high grade metamorphic rocks in the area of Daqingshan, Inner Molgolia. In this association, the various large scale ductile deformation belts, form a nappe structure where the foliation steeply dips to north and the lineation ($340^{circ}-30^{\circ}$) plunges at $45^{\circ}55^{\circ}$. This result indicates the subduction/extension with northern part thrusting over the southern part at high angle. The southern subducted microlithon has the characteristics of prograde metamorphism. The northern thrusted microlithon shows the evidence of retrograde metamorphism with decreasing pressure and increasing temperature. The main rock types of Early Proterozoic Moyites are biotite adamellite and syenogranites occurring in the form of small batholiths or stocks and alkali-feldspar granites in veins. The biotite adamellites are progressively contacted with the Archean and Early Proterozoic rocks and contain a great deal of enclaves of metamorphosed rocks, suggesting an anatexis origin. The geochemical characteristics of moyites show the typical features of anatexis granite. At middle to late Early Proterozoic time, the continent-continent collision formed the large scale thrusting and imbrication of Archean basement rocks. According to the mineral assemblage and thermobarometer of Paria et al. (1988) give the following P-T condition : up-faulted block; $700-710^{\circ}C$, 0.72-0.78 Gpa (early stage) and $600^{\circ}C$, 0.44 Gpa (late stage), footwall block; $620^{\circ}C$, 0.8 Gpa (early stage), $620-840^{\circ}C$, 0.64-0.45 Gpa (peak) and $620-630^{\circ}C$, 0.35Gpa (late stage). These results suggest a clockwise P-T-t path (jin et al., 1991, 1994). According to the depth-temperature model in the comperature subduction zone and the experimental data of Wyllie et al. (1983), we propose a tectonic-magmatic-thermal model to account for metamorphism-anatexis of moyite occurring in subduction-shear zone.

• Advances in concrete construction
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• v.13 no.6
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• pp.411-422
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• 2022

Aggregates mineralogical, and petrographic properties directly affect the mechanical properties of the produced high strength. This study is focused on the effects of magmatic, sedimentary, and metamorphic aggregates on the performance of high strength concrete. In this study, the effect of the mineralogical properties of aggregates on the compressive strength and modulus of elasticity of high-strength concrete was estimated by Artifical Neural Network (ANN). To estimate the compressive strength and elasticity modules, 96 test specimens were produced. After 28 days under suitable conditions, tests were carried out to determine the compressive strength and modulus of elasticity of the test specimens. This study also focused on the application of artificial neural networks (ANN) to predict the 28-day compressive strength and the modulus of elasticity of high-strength concrete. An ANN model is developed, trained, and tested by using the available test data obtained from the experimental studies. The ANN model is found to predict the modulus of elasticity, and 28 days compressive strength of high strength concrete well, within the ranges of the input parameters. These comparisons show that ANNs have a strong potential to predict the compressive strength and modulus of elasticity of high-strength concrete over the range of input parameters considered.

• Journal of the Korean earth science society
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• v.27 no.6
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• pp.620-642
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• 2006

The Moho structure and its deformation in the southern part of the Korean Peninsula were estimated using gravity and topography data. Gravity signals from the upper and lower crust were separated using a filter that was computed from isostacy and elastic thickness. The result of this study shows three characteristic features of the Moho deformation. First, the Moho folding structure is parallel to SKTL (the South Korean Tectonic Line), which indicates positive association with the collision of the Yeongnam and Gyeonggi Massifs and repeated compression afterwards. In contrast, noticeable deformation of the Moho was not observed along the Imjingang Belt, which is interpreted as another continental collisional belt in the Korean Peninsula. Second, the Moho beneath the Gyeongsang Basin has remarkably risen; this seems to be the result from both the collisional compression and buoyancy caused by magmatic underplating. Third, the Moho deformation is shallowest in the east of the Taebaek Mountains and deepens toward the west, consistent with the topographic characteristic of the Korean Peninsula of "high east and low west". It can be interpreted as the results of the opening of the East Sea and Ulleung Basin. A tectonic explanation for this could be the ascent of the mantle induced by continental rifting and horizontal extension at the early stage of the opening of the East Sea. The Moho deformation model computed in this study correlates well with the earthquake distribution and crustal movement measured by GPS. We suggest that the compression along the SKTL is still exerted, consequently, the Moho deformation is active, although it may be weak.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.97-100
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• 2008

Mount Fuji is the focus of intense study because of its potential hazard signaled by seismic, geologic and historical activity. Based on extensive seismic data recorded in the vicinity of Mt. Fuji, coda quality factor ($Q_c^{-1}$) using a single scattering model hypothesis, and intrinsic and scattering quality factor $(Q_i^{-1}$ and $Q_s^{-1})$ using the Multiple Lapse Time Window Analysis (MLTW) method was measured. To focus the study on the magmatic structure below Mt. Fuji, to the data were separated into two groups: a near-Fuji region of rays traversing an area with radius 5 km around the summit (R < 5 km), and a far-Fuji region of rays beyond a radius of 20 km around the summit (R > 20 km). The results of the study have a small error range due to the large data sample, showing that all $Q^{-1}$ values in near-Fuji area are greater than those of far-Fuji area, and $Q_i^{-1}$ for both the near and far-Fuji area is higher than $Q_s^{-1}$ at high frequencies. The $Q_i^{-1}$ values of the near-Fuji area are lower than those of the other volcanic areas considered, while values of $Q_s^{-1}$ are not. The low $Q_i^{-1}$ for the volcanic region of near-Fuji suggests that the magmatic activity, or percent of partial melt, at Mt. Fuji is not as active as hot spot volcanoes such as Kilauea, Hawaii.

• Economic and Environmental Geology
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• v.32 no.6
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• pp.561-573
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• 1999

Mesothermal gold deposits of the Heungdeok, Daewon and Ilsaeng mines in the Youngdong area occur in fault shear zones in Precambrian metamorphic rocks of central Sobaegsan Massif, Korea, and formed in single stage of massive quartz veins (0.3 to 3 m thick). Ore mineralogy is simple, consisting dominantly of pyrrhotite, sphalerite and galena with subordinate pyrite, chalcopyrite, electrum, tetrahedrite and native bismuth. Fluid inclusion data indicate that hydrothermal mineralization occurred at high temperatures (>240$^{\circ}$ to 400$^{\circ}$C) from $H_{2}O-CO_{2}(-CH_{4})$-NaCI fluids with salinities less than 12 wt. % equiv. NaC!. Fluid inclusions in vein quartz comprise two main types. These are, in decreasing order of abundance, type I (aqueous liquid-rich) and type II (carbonic). Volumetric proportion of the carbonic phase in type II inclusions varies widely in a single quartz grain. Estimated $CH_4$ contents in the carbonic phase of type II inclusions are 2 to 20 mole %. Relationship between homogenization temperature and salinity of fluid inclusions suggests a complex history of fluid evolution, comprising the early fluid's unmixing accompanying $CO_2$ effervescence and later cooling. Estimated pressures of vein filling are at least 2 kbars. The ore mineralization formed from a magmatic fluid with the ${\delta}^{34}S_{{\Sigma}S}$, ${\delta}^{18}O_{water}$ and ${\delta}D_{water}$ values of -2.1 to 2.2$\textperthousand$, 4.7 to 9.3$\textperthousand$ and -63 to -79$\textperthousand$, respectively. This study validates the application of a magmatic model for the genesis of mesothermal gold deposits in Youngdong area.