• Journal of the Geological Society of Korea
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• v.54 no.6
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• pp.683-694
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• 2018

Subduction has been the focal point of numerical studies for decades because it plays an important role in the Earth's mass and energy circulations and generates earthquakes and arc volcanoes which are closely related to the human lives. Among the studies on subduction, numerical modeling has been broadly applied to the quantitative studies on the subducting slab in the mantle which cannot be directly observed. In this study, we benchmark the numerical subduction modeling using a finite element package, COMSOL $Multiphysics^{(R)}$ and the results are consistent with the previously reported benchmark results.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.207-207
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• 2006

• Journal of the Korean earth science society
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• v.25 no.4
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• pp.222-231
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• 2004

The purpose of this study is to analyze the seventh curriculum textbooks and teacher's guides of high school science courses in relation to the generation (mechanism) of magma in subduction boundary and find the incorrect descriptions of the texts and the figures (illustrations) and then suggest some improved schemes. According to the result there are many discrepancies in definition of 'magma' among the textbooks and further little scientific explanations about the formation mechanism of magma in most textbooks, and even no descriptions about that. In addition, the figures are inconsistent with the description of the text and also have some incorrect depiction which might contribute to the forming and reinforcing misconceptions about Plate Tectonics as well as a volcanic activity in subduction boundary. On the basis of the previous researches, therefore, some improved schemes (text descriptions and figures) are suggested. The results of this study should be used as a reference for publishing science textbook, developing science curriculum, and teaching effectively in the high school.

• Economic and Environmental Geology
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• v.52 no.5
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• pp.337-345
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• 2019

The hypothesis of ridge subduction which explains the Cretaceous igneous activities in East Asia including China, Korea and Japan, has been widely accepted in the society. Especially, the hypothesis explains the southwest-to-northeast migration of the Cretaceous adakite emergence in Southwest Japan. However, the hypothesis has several issues because the geochemical analyses and plate reconstruction model are not consistent with the consequences of the ridge subduction. To resolve the issues, a new hypothesis of the plume-continent and plume-slab interaction is suggested, which explains the igneous activities during the Cretaceous. In this review, I briefly introduce the two hypotheses and suggest an additional future study to prove the new hypothesis.

• 한국지구과학회:학술대회논문집
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• 2003.09a
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• pp.79-87
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• 2003

• The Journal of the Petrological Society of Korea
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• v.21 no.2
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• pp.203-216
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• 2012

Based on the petrologic and age data of the Cretaceous to early Tertiary granites in south Korea, we propose a new tectonic model reflecting their temporal and spatial variations. A number of petrographic and geochemical studies on the granites suggest that they originated from the magma formed by subduction of oceanic crust in continental margin and were emplaced in epizone. The MMEs with various shapes and sizes, which were produced due to the magma mixing caused by the injection of mafic magma from mantle during the crystallization of the granitic magma, are observed in the granites. The distributions of the MMEs and ages of the granites show a distinctive spatio-temporal distribution pattern. The distribution pattern can be explained by a multiple slab window model related to the ridge subduction of Izanagi-Pacific plates during the Late Cretaceous.

• Economic and Environmental Geology
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• v.37 no.3
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• pp.269-276
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• 2004

The Indonesian Archipelago is located in the southern tip of the Eurasian plate. The diverse subduction system of the Indonesia region records interactions between three megaplates (Eurasian, Indian-Australian, and Pacific plates) and many smaller plates. The geology of Indonesian Archipelago is characterized by many factors such as subduction zone complexes, magmatic arc rocks associated with plate tectonics, the arc granite and volcanic rocks, and the related metamorphic rocks. The base-metal deposits of Indonesia have a great effect on petrochemical character of parent rocks and geotectonic environments. The base-metal deposits can be classified into four types as hosted by felsic-intermediate intrusive rocks, hosted by ultramafic rocks, hosted by volcanic rocks, and hosted by sedimentary rocks. The gold deposits are divided into three types: epithermal gold deposits, porphyry copper associated gold deposits, and alluvial gold deposits. Especially, Indonesian island uc, with its numerous plates tectonic, has an high potential for epithermal gold deposits. Indonesia with many old and present subduction zones and sub-aerial calcalkaline volcanic rocks is a very promising country for epithermal gold mineralization.

• Economic and Environmental Geology
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• v.32 no.4
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• pp.323-337
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• 1999

Late Cretaceous to early Tertiary volcanic rocks in the Kyongsang basin exhibit high-K calc-alkaline characteristics, and originated from the magmatism related genetically to subduction of Kula-Pacific plate. They represent HFSE depletion and LlLE enrichment characteristics as shown by magmas related to subduction. Early studies on the depth of magma generation has been estimated as 180-230 km based on K-h relation should be reevaluated, because the depth of peridotite partial melting with 0.4 wt. % water is 80-120 km at subduction zone, and subducting slab in premature arc can melted even lower than 70 km. Moreover the increase of potassium contents depends on either contamination of crustal material and fluids of subducting slab or low degree of partial melting. If the inclination of subduction zone is 30 degrees and the depth to the Benioff zone is 180-230 km, the calculated distance between the volcanic zone and trench axis would be 310-400 km. It is unlikely because the distance between the Kyongsang basin and trench during late Cretaceous to early Tertiary is closer than this value and not comparable with generally-accepted models in subduction zone magmatism. $K_{55}$ of the volcanics in the Kyongsang basin is 0.3-2.3 wt.% and the average indicate that the depth ranges between 80-170 km on the diagram of Marsh, Carmichael (1974). Fractionation from garnet lherzolite, assumed the depth of 180-230km, is not consistent with the REE patterns of the volcanoes in the Kyongsang basin. Futhermore, the range of depth suggested by many workers, who studied magmatism related to subduction, imply shallower than this depth. Crustal thickness calculated by the content of CaO and $Na_2O$ is about 30 km and about 35 km, respectively. Paleo-crustal thickness during late Cretaceous to early Tertiary times in the Kyongsang basin inferred about 30 km calculated by La/Sm versus LaJYb data, which is also supported by many previous studies.

• The Journal of the Petrological Society of Korea
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• v.21 no.2
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• pp.59-87
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• 2012

Recent studies reveal that eclogite formed in the Hongseong area and post collision igneous rocks occurred throughout the Gyeonggi Massif during the Triassic Songrim Orogeny. These new findings derive the tectonic model in which the Triassic Qinling-Dabie-Sulu collision belt between the North and South China blocks extends into the Hongseong-Yangpyeong-Odesan collision belt in Korea. The belt may be further extended into the late Paleozoic subduction complex in the Yanji belt in North Korea through the Paleozoic subduction complex in the inner part of SW Japan. The collision belt divides the Gyeonggi Massif into two parts; the northern and southern parts can be correlated to the North and South China blocks, respectively. The collision had started from Korea at ca. 250 Ma and propagated to China. The collision completed during late Triassic. The metamorphic conditions systematically change along the collision belt:. ultrahigh temperature metamorphism occurred in the Odesan area at 245-230Ma, high-pressure metamorphism in the Hongseong area at 230 Ma and ultra high-pressure metamorphism in the Dabie and Sulu belts. This systematic change may be due to the increase in the depth of slab break-off towards west, which might be related to the increase of the amounts of subducted ocecnic slab towards west. The wide distribution of Permo-Triassic arc-related granitoids in the Yeongnam Massif and in the southern part of the South China block indicate the Permo-Triassic subduction along the southern boundary of the South China block which may be caused by the Permo-Triassic collision between the North and South China blocks. These studies suggest that the Songrim orogeny constructed the Korean Peninsula by continent collision and caused the subduction along the southern margin of the Yeongnam Massif. Both the northern and southern Gyeonggi Massifs had undergone 1870-1840 Ma igneous and metamorphic activities due to continent collision and subduction related to the amalgamation of Colombia Supercontinent. The Okcheon metamorphic belt can be correlated to the Nanhua rift formed at 760 Ma within the South China blocks. In that case, the southern Gyeonggi Massif and Yeongnam Massif can be correlated to the Yangtz and Cathaysia blocks in the South China block, respectively. Recently possible Devonian or late Paleozoic sediments are recognized within the Gyeonggi Massif by finding of Silurian and Devonian detrital zircons. Together with the Devonian metamorphism in the Hongseong and Kwangcheon areas, the possible middle Paleozoic sediments indicate an active tectonic activity within the Gyeonggi Massif during middle Paleozoic before the Permo-Triassic collision.

• Journal of the Korean Geographical Society
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• v.47 no.3
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• pp.328-346
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• 2012

This study provides quantitative constraints on Neogene uplift in the Korean peninsula using onshore paleo-shoreline records and seismic data. The eastern margin of Northeast Asia including Korea sits in the back-arc system behind the Western Pacific Subduction Zone, a complex trench triple junction of the Philippine Sea, Pacific, and Eurasian (Amurian) plates. An analysis of seismic data in the subduction zone shows that the pattern of uplift in the peninsula mirrors the extent of deep seismicity in subducting Pacific plate beneath. Combined with previous tomographic studies it is proposed that uplift is partly driven by asthenospheric upwelling caused by a sinking slab during the Neogene. In addition, the SHmax orientations of E-W and N-S trends in the peninsula are consistent with the prevailing in-situ stress fields in the eastern Eurasian continent generated by various plate boundary forces. The uplift in Korea during the Late Neogene is attributed, in part, to lithospheric failure relating to faulting movements, thus providing a link between dynamic effects of mantle upwelling at sinking slab edge and lithospheric responses driven by plate boundary forces.