• The Journal of Engineering Geology
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• v.19 no.3
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• pp.287-294
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• 2009

To be design the slope, the area distributed the mica schist which was metamorphosed by shale or mudstone must carefully consider the stability. Mica schist is another unstable rock for slope by schistosity, cleavage, axial plane of a fold etc. In general mica schist contains the swelling clay minerals such as smectite, vermiculite and montmorillonite. These minerals make the slope unstable. At OO tunnel construction area for the rail way of the Kyungbu high speed train, the slope of mica schist is very unstable by the distribution phenomena of the discontinuous plane such as joints which are 1-5 cm spacing and thrust and strike-slip fault. By the drilling core of this area, most RQD have 0-20%.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.3
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• pp.233-237
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• 2000

The complete postembryonic development of nauplius stages of Paramphiascella vararensis T. Scotf (Copepoda: Harpacticoida) is described and illustrated based on specimens cultured in laboratory. The nauplii of P. vararensis feed on powder of a green algae, Ulva perusa. This species is metamorphosed to the stages of nauplius. Development from the nauplius stage to the nauplius stage take about 12 days under culture conditions of 33-34 ppt of salinity, 22-23$^{\circ}$C of temperature and feed on the algal powder. In the nauplius stages of P. vararensis, the rudiment of maxillule appeares at the third nauplius stage, and maxilla appeares at the fifth nauplius stage.

• Economic and Environmental Geology
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• v.17 no.4
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• pp.299-314
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• 1984

The Yeongdo Island in Busan City is a remnant of the latest Cretaceous volcano, and consists geologically of andesites, rhyolite tuff, pelitic and psammitic hornfelses, lapilli rhyodacite tuff of the Yucheon Group, felsite and felsite porphyry of the Bulgugsa intrusives, and Holocene sediments in ascending order. The hornfelses are bound to the Taejongdae Formation. The stratigraphic position of the Formation is determined definitely into the Yucheon Group, thus the geologic age is approximately the same with the volcanic rocks of the Group. The sediments had been thermally metamorphosed to make pelitic and psammitic hornfelses of the albite epidote hornfels facies by the effects of active hydrothermal circulation, vaporization, and hybridization of andesitic solution, or of basification of acidic intrusives. Thus, on occasion, those hornfelses are not used to be distinguished from the andesitic rocks in the southeastern part of the Korean peninsula. The paleocurrent direction determined from several cross-beddings of the Taejongdae Formation is suggested to be from southwest to northeast. Orbicular rocks occur in hornfelsed rhyolite tuff, pelitic- and psammitic-hornfelses, and felsite porphyry at a lot of outcrops in the area of southwestern shoreline of the Yeongdo Island. Orbicules in rhyolite tuff and hornfels in the island might have originated from diffusion processes of metasomatic metamorphism carried out by hydrothermal solution rised from the intrusive adamellite which may be emplaced deeply under the Yeongdo volcanics. Those orbicules are due to metasomatic, secondary, and epigenetic origin. Proto-, multi-shelled, and multi-cored orbicules are described in the orbicular tuff. But multi-cored orbicules are not found in the orbicular fornfels. 250 tuff-orbicules numbered sporadically are in $20,000m^2$ area of the locality of orbicular tuff. About 60 hornfels-orbicules occurred sporadically are in $1,700m^2$ area of the locality of orbicular hornfels in the Taejongdae Formation. Orbicules in felsite porphyry might have originated by diffusion reaction between xenoliths and a quiescent zone in felsite porphyry magma. Those are of igneous, primary, and syngenetic origin.

• Economic and Environmental Geology
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• v.6 no.3
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• pp.133-170
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• 1973

The metamorphosed belt on cherty and andesitic rocks of the Gyeongnam province area has been well known as the most important copper matallogenetic province in Korea and locally has been investigated by several geologists. This report is summarized about geology, occurrence of ore deposits, the study of the present status of mine developments and exploitations and the suggestions of future proposed of copper mine developments and harmoniously and reseonably planning of demands and supply of copper ore. For convenience of study the writer divided the survey region as 4 areas, according to the conditions of mine location. They are (1) Goseong copper area (2) Gunbuk-Haman copper area (3) Masan-Changwon copper area (4) Tongrae-Ilgwang copper area. The geology of the above 4 areas consits of Cretaceous Gyongsang System, which is divided into Silla series, Nakdong Series and Bulguksa Series. The former has intrusive and extrusive andesite and sedimentary formation, and the latter has dioritic and hornblende granite. Ore deposits which is mostly vein types are confined mostly in the andesite and cherty rocks of Silla and Nakdong Series. It is observed slight hydrothermal alteration, i. e. propylitization, chloritization, saussuritization and silicification. It seems that the ore was formed by hydrothermal solution and secondary enrichement. The ore minerals are mainly chalcopyrite and pyrite, with small amounts of malachite, azurite, chalcocite, cuprite, galena, and sphalerite, magnetite, tetrahedrite and etc.. The efficient plan of copper mine developments in surveyed region are as following; (a) Gyeongnam Copper districts are divided in 4 area as mentioned above. (b) Each area would be likely developed as group-working as one unit. For the sufficiently supplying a demand of electric copper, the importations of high grade copper ore in foreign country are invitable at present status of copper mine developments and exploitations.

• Economic and Environmental Geology
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• v.23 no.1
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• pp.35-57
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• 1990

This study has been carried out on the Pegmatites, Naedeogri Granites, Nonggeori Granites and Metasedimentary rocks in the middle area of Taebaeksan region to investigate the geochemical properties and possibility of productivity. Pegmatites are characterized by metamorphosed anatectic pegmatite and differentiated magmatic pegmatite, and are mixed type of rare-element pegmatite and mica-bearing pegmatite by the classification of Ginsburg(1979). The petrological type of the igneous rocks is thought to be calcalkali, subalkaline and peralumious. According to chemical variations against D. I., differentiation trends from Naedeogri and Nonggeori Granites through non-mineralized pegmatites to mineralized pegmatites are supposed. From the relationship between oxided and $SiO_2$, pegmatites and Nonggeori Granite have shown similar tendencies and bulk composition of pegmatites and similar to metasedimentary rocks near the intrusives. By judging the correlations of trace elements, it is elucidated that pegmatites adjacent to Naedeogri and Nonggeori Granites have been originated in magma differentiation from these granites and the others have been differentiated by remelting or partial melting from metasedimentary rocks. $Sp_5$, $Sp_8$, and $Sp_9$ pegmatites are considered as productive rocks, and $Sp_4$, $Sp_6$, $Sp_7$, $Sp_{10}$, $Sp_{11}$, and $Sp_{12}$ pegmatites and granites are supposed to have a weak productivity, in terms of element ratios related with Sn mineralizations. Tourmalines in productive pegmatites are formed under the circumstance of Li-poor granitoids and associated with pegmatites, and the others are seemed to be originated in metapelites and metapsammites which are not coexisting with an Al-saturating phase. Three types of chemical zoning are noticed in tourmalines: (1) apparently homogeneous compositional patterns, (2) a continuous core-to-rim zoning and, (3) a discontinuous core-to-rim zoning. From results of EPMA of tourmalines, Al, Mg and Ca increase closer to rim, while Fe decreases.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.2
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• pp.98-104
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• 2004

Early development and metamorphosis of the ascidian (Halocynthia hilgendorfi ritteri) were investigated from fertilized egg. The samples were collected in the coastal waters of Yongdam, northwest of Jeju Island in November 2002. H. hilgendorfi ritteri was solitary ascidian and produced spheral eggs with egg size ranging from $0.33\pm0.01\;mm.$ On the outer surface of the vitelline coat are attached many follicle cells. At $21.0\pm0.5^{\circ}C$ of water temperature, first cleavage took place in about 1.5 hrs after fertilization, and gastrulation followed in about 12.5 hrs. The formation of tailbud embryos and free swimming larvae were observed 13.3 hrs and 20.5 hrs after fertilization, respectively. The size of newly hatched tadpole larva was 1.30-1.45 mm, the larva swam for 2 hrs to 14 hrs. At 4 hrs after hatching, the palpi were lost and tail absorption began with an abrupt rupture of the anterior end of the notochord. At 17-18 hrs after hatching, tail completely absorption and remained trunk. The coniform adhesive papilla began protrusion at 30 hrs after hatching. The oral and atrial siphon formed at 6-7 days after settlement. At 17-18 days after settlement, metamorphosed the larvae developed into protoascidian of which the external morphology was similar to their adult.

• The Korean Journal of Quaternary Research
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• v.1 no.1
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• pp.35-45
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• 1987

Several fluvial terraces were developed in the Kajo Basin located in Kochang-gun, Kyongsangnam-do, Korea. The peat layers are formed on a fluvial terrace of them. To clarify the geomorphic development of this basin, a detailed classification of geomorphic surfaces, a soil profile study, grain size analysis, pollen analysis of the peat layers and C-14 dating were made. The main findings are as follows: 1) The Kajo Basin was formed by a differential erosion of granic rocks. The surrounding mountains are contact-metamorphosed gneiss and sedimentary rocks. 2) Seven geomorphic surfaces were recognized. They are named the H1, H2, M1, M2, T, L1 and L2 surfaces, from older to younger. 3) C-14 dating and the pollen analysis indicate that the L1 surface was formed during the Early Wurm Glacial. 4) The formation periods of the L2, M and H surfaces are supposed to be the Late Wurm, Riss and Mindel glacial, respectively, on the basis of the color of soil horizons (with or without the Red Soil) and the weathering degree of gravels. 5) Betula and Pices were dominant in the pollen of the Kajo Basin around 30,000 years B.P.

• Journal of the Korean Geotechnical Society
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• v.18 no.2
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• pp.65-74
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• 2002

The measurement of in-situ stress is essential to estimate the ground displacement and the stress distribution of a tunnel and an underground structure. In this study, the in-situ stress distribution of the Southern Korean peninsula was re-evaluated by the new 380 in-situ data which were determined by overcoring and hydrofracturing methods, and the three-din erosional numerical analysis of tunnelling was performed. The results of in-situ stress distribution show that the distribution of horizontal stress tends to be more irregular in metamorphosed(gneiss) and granite areas than in sedimentary and volcanic areas. The ratio of horizontal to vertical stresses(K-value) in volcanic area is less than 1 below the depth of 150m. The direction and magnitude of three dimensional in-situ stresses were shown simultaneously in a figure for the first time in Korea. The three-dimensional numerical analysis of tunnelling indicates that the orientation and magnitude of displacement around a tunnel are controlled mainly by the difference between the maximum and minimum horizontal stresses.

• Economic and Environmental Geology
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• v.17 no.3
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• pp.197-214
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• 1984

This studg is to clarify intrusion sequence and petrogenetic processes of the so-called schistose granites in the northeastheastern part of the Kwangju, Chonnam Province. The study area is composed of the Pre-cambrian and Unknown age metasediments, the Unknown age schistose granites and basic plutons, the Cretaceous sedimentary and volcanic rocks, and the Cretaceous Ogang-ri granite and dykes. The schistose granites of the study area is divided into three rock units based on relative intrusion age, mineralogical constituent and texture;SoonChang schistose granite, two mica granite and Sam-o-ri schistose granite. The schistose granites intruded into metasediments, are intruded by Ogang-ri granite and dikes, and overlain by the Cretaceous sedimentary and volcanic rocks. The schistose granites vary widely in composition (granite-granodiorite-tonalite) and content of porphyroblastic feldspar Caugen and rectangular shaped). The foliation of schistose granites shows similar trend to the Shinian direction. In especially, strong foliation reflects dynamic metamorphism by mortar texture and much content of well oriented biotite. These schistose granites are characterized by its gray feldspar porphyroblasts. This feldspar is considered to be formed by potassic metasomatism and assimilation of pelitic metasediments of unexposed highly metamorphosed rocks deeply buried under the level of the schistose granites emplacement. Variation of silica versus oxides of major elements shows that the schistose granites are similar to the trend of Daly's average basalt-andesite-dacite-rhyolite which shows the trend of the fractional crystallization of magma. AMF diagram shows that the schistose granite is corresponded to contaminated differentiation products such as Lower California batholith and Cascade lava. These evidence suggest that the schistose granite is a series of differentiation products formed by fractional crystallization that associated with srtongly contamination and potassic metasomatism.

• The Journal of Engineering Geology
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• v.17 no.4
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• pp.589-599
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• 2007

For the preliminary judgement on the chemical stability of concrete aggregates mixed with cement paste, ASTM C 295 method can be applied prior to the long-term chemical test methods. By using this standard test method, the petrographic study on the appropriateness of natural KEDO aggregates for concrete was carried out. With the natural gravel and sand aggregates, the polarized microscope, stereoscopic microscope, and X-ray diffractometer were used for examination. The result shows the 23% of gravel aggregates and 5.1% of sand aggregates are chemically unstable. To select the favorable KEDO concrete aggregates, it is required to exclude the highly metamorphosed rocks, acidic volcanic rocks, highly foliated rocks, and expansive rocks identified from mortar-bar test. Further chemical test and mortar-bar test method integrated with this study is recommended for the suitability assessment of natural KEDO concrete aggregates.