• The Journal of the Petrological Society of Korea
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• v.9 no.4
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• pp.238-253
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• 2000

In the eastern part of the Euiseong Basin acidic~intermediate volcanic rocks widely distribute on the Cretaceous sedimentary basement. Coeval granitic rocks and dyke rocks intruded into the volcanic rocks. Volcanic stratigraphy of study area are andesite lava, dacitic lapilli tuff, dacitic flow-banded lava, rhyolitic bedded tuff, rhyolitic massive tuff, dacitic massive lava, rhyolitlc welded tuff occur from the lower to the upper strata. $SiO_2$ content of the volcanic rocks range from 51 to 74 wt.%. With the increase of $SiO_2$, the contents of $TiO_2$, $Al_2$$O_3$, MgO, FeOT MnO, CaO, $P_2$$O_{5}$ decrease but those of $K_2$O increase. The contents of $Na_2$O show dispersive variation. This trend is quite sim-ilar to the major oxide variation in the volcanic rocks from the Yucheon sub-basin. The geochemical natures indicate that the volcanic rocks in the study area are discriminated to the island-arc type high K to medium K calc-alkaline rocks. The compositional variation of the volcanic rocks can be explained by the plagioclase fractionation of the volcanic magmas originated from similar source materials. The volcanic stratigraphy seems to have formed by at least two eruptive sequences of andesitic to rhyolitic and dacitic to rhyolitic magmas which underwent crystallization differentiation.

• Korean Journal of Medicinal Crop Science
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• v.5 no.3
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• pp.243-248
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• 1997

Cyperus rotundus has been grown for a long time in korea to be used as medicinal crop. This study was conducted to survey the production status and economic analysis in chief producing area of Cyperus rotundus in Koryong, Korea. The Koryong area where was the major production area of Cyperus rotundus was composed of 0.6hectare cultivation size per farm household and the processes like cultivation, processing, shipping were formed unitedly. The most general management type was labor-extensive one which use the Nakdong river basin or idle land effectively. The cultivation area have been decreased gradually because the price was very low so that the income per hectare was just 3,880 thousand won and productivity per hectare was just 6,280kg. Thus, production condition was very inferior, it needs some self-help to encourage the production because it has some possibility as only regional special product.

• Economic and Environmental Geology
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• v.36 no.4
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• pp.257-268
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• 2003

The Cretaceous magmatism in the Gyeongsang Basin, Korea, led to the formation of two contrasting metallogenic provinces: the Haman-Gunbug-Goseong(-Changwon) (HGGC) and the Euiseong (EU). The mineralization in the HGGC metallogenic province represents copper, gold and iron of porphyry-related deposits that display close relationships in time and space with subvolcanic granitoids. Much of copper-gold-forming events in this province are consistently constrained to the period between ca. 89 and 81 Ma. The hydrothermal systems of copper-gold vein deposits in the HGGC province are associated with ore-forming fluids of high to intermediate temperature (300∼50$0^{\circ}C$) with high salinity (20∼55 equiv. wt. % NaCl). The ore-forming fluids become progressively more diluted by the incorporation of decreased quantities of magmatic water further from the nearby intrusion, suggesting significant input and fluid mixing of a meteoric water component to the magmatic fluids during the late stage of geothermal systems. In contrast, the EU metallogenic province is characterized by polymetallic vein deposits that are consistently constrained to a period of 78∼60 Ma. The geothermal systems of polymetallic vein deposits in the EU province are derived from a narrow range of intermediate temperature (200∼40$0^{\circ}C$) with relatively low salinity(1∼7 equiv. wt.% NaCl). It may represent a mixed fluid of magmatic and meteoric waters. The base-metal mineralization in the Gyeongsang Basin shows a close spatial and temporal distinction between the proximal environment derived from shallow-level granitoids in the southwestern HGGC province and the distal condition derived from volcanic environments in the northwestern EU province.

• The Journal of the Petrological Society of Korea
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• v.6 no.2
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• pp.111-122
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• 1997

Provenance type and paleoclimate of the Jinju and Iljig formation were studied on the basis of compositions of sandstones from the western Euiseong area in the northern part of Kyong-sang basin. The average compositions of quartz, feldspar and lithic grain(Q:F:L) from the sandstones are 53:40:7 and 50:46:4 for Jinju and Iljig formations, respectively. The values fall into the arkosic arenite field. Petrographic detrital modes of the sandstones mainly suggest transitional continental block for the tectonic setting of the provenance. All sandstones from the Jinju and IIjig formations show chemical compositions close to average values of arkose(Pettijohn, 1975). $Na_2O$ contents is relatively high. $Fe_2O_3$(total iron) and MgO contents decrease with increasing $SiO_2$ contents since the framework grains of arkoses supposed to be derived from granitic rocks are poor in ferromagnesian minerals. The detrital framework grains still possess climatic signs even though the grains were more or less altered during deep burial. Bivariant plot of Suttner and Dutta(1986) suggests semi-arid to semi-humid paleoclimate during the deposition of the Jinju and Iljig sandstones.

• Economic and Environmental Geology
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• v.22 no.3
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• pp.253-266
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• 1989

The Cu-Pb-Zn-Ag hydrothermal vein type deposits which comprise the Dongil and Dong-cheogogsan mines occur within the Cretaceous sedimentary rocks in the Euiseong Basin of the southern Korean peninsula. The ore mineralization is contained within three stage(I,II and III) quartz and calcite veins. Ore minerals occur as dominant chalcopyrite, galena, sphalerite, tetrahedrite and Pb, Ag, Sb and Bi-bearing sulfosalts. Stage I ore minerals were deposited between $400^{\circ}C$ and $200^{\circ}C$ from the fluid with moderate salinities(7.0 to 4.5 eq. wt. % NaCl). Evidence of boiling suggests pressure of less than 150 bars during stage I mineralization. This pressure corresponds to maximum depths of 650 m and 1700 m, respectively, assuming lithostatic and hydrostatic loads. The data on mineralogy, temperature and salinity, together with information on the solubility of Cu complex, suggest that Cu deposition is a result of boiling coupled with declining temperature from $350^{\circ}$ to $250^{\circ}C$ or declining log $a_{o_2}$(from -29.8 to -35.9 atm.)and increasing in pH. Pb, Ag, Sb and Bi-bearing sulfosalts were deposited by cooling and dilution at temperature of less than $250^{\circ}C$ from the ore fluid with less than -35.9 atm. of log $a_{o_2}$.

• Economic and Environmental Geology
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• v.25 no.4
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• pp.417-433
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• 1992

Lead-zinc-copper deposits of the Jeonheung and the Oksan mines around Euiseong area occur as hydrothermal quartz and calcite veins that crosscut Cretaceous sedimentary rocks of the Gyeongsang Basin. The mineralization occurred in three distinct stages (I, II, and III): (I) quartz-sulfides-sulfosalts-hematite mineralization stage; (II) barren quartz-fluorite stage; and (III) barren calcite stage. Stage I ore minerals comprise pyrite, chalcopyrite, sphalerite, galena and Pb-Ag-Bi-Sb sulfosalts. Mineralogies of the two mines are different, and arsenopyrite, pyrrhotite, tetrahedrite and iron-rich (up to 21 mole % FeS) sphalerite are restricted to the Oksan mine. A K-Ar radiometric dating for sericite indicates that the Pb-Zn-Cu deposits of the Euiseong area were formed during late Cretaceous age ($62.3{\pm}2.8Ma$), likely associated with a subvolcanic activity related to the volcanic complex in the nearby Geumseongsan Caldera and the ubiquitous felsite dykes. Stage I mineralization occurred at temperatures between > $380^{\circ}C$ and $240^{\circ}C$ from fluids with salinities between 6.3 and 0.7 equiv. wt. % NaCl. The chalcopyrite deposition occurred mostly at higher temperatures of > $300^{\circ}C$. Fluid inclusion data indicate that the Pb-Zn-Cu ore mineralization resulted from a complex history of boiling, cooling and dilution of ore fluids. The mineralization at Jeonheung resulted mainly from cooling and dilution by an influx of cooler meteoric waters, whereas the mineralization at Oksan was largely due to fluid boiling. Evidence of fluid boiling suggests that pressures decreased from about 210 bars to 80 bars. This corresponds to a depth of about 900 m in a hydrothermal system that changed from lithostatic (closed) toward hydrostatic (open) conditions. Sulfur isotope compositions of sulfide minerals (${\delta}^{34}S=2.9{\sim}9.6$ per mil) indicate that the ${\delta}^{34}S_{{\Sigma}S}$ value of ore fluids was ${\approx}8.6$ per mil. This ${\delta}^{34}S_{{\Sigma}S}$ value is likely consistent with an igneous sulfur mixed with sulfates (?) in surrounding sedimentary rocks. Measured and calculated hydrogen and oxygen isotope values of ore-forming fluids suggest meteoric water dominance, approaching unexchanged meteoric water values. Equilibrium thermodynamic interpretation indicates that the temperature versus $fs_2$ variation of stage I ore fluids differed between the two mines as follows: the $fs_2$ of ore fluids at Jeonheung changed with decreasing temperature constantly near the pyrite-hematite-magnetite sulfidation curve, whereas those at Oksan changed from the pyrite-pyrrhotite sulfidation state towards the pyrite-hematite-magnetite state. The shift in minerals precipitated during stage I also reflects a concomitant $fo_2$ increase, probably due to mixing of ore fluids with cooler, more oxidizing meteoric waters. Thermodynamic consideration of copper solubility suggests that the ore-forming fluids cooled through boiling at Oksan and mixing with less-evolved meteoric waters at Jeonheung, and that this cooling was the main cause of copper deposition through destabilization of copper chloride complexes.

• Korean Journal of Remote Sensing
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• v.12 no.2
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• pp.139-154
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• 1996

In order to evaluate the sensor`s look direction bias in the Landsat TM image and to estimate trends of primary geological lineaments, we have attempted to systematically compare lineaments in TM image, relief shadowed DEM's, and actual lineaments of geologic and topographic map through the Hough transform technique. Hough transform is known to be very effective to estimate the trend of geological lineaments, and help us to obtain the true trends of lineaments. It is often necessary to compensate the preferential enhancements of terrain lineaments in a TM image occurred by to look direction bias, and that can be achieved by utilizing an auxiliary data. In this study, we have successfully adopted the relief shadowed DEM in which the illuminating azimuth angle is perpendicular to look direction of a TM image for assessing true trends of geological lineaments. The results also show that the sum of four relief shadowed DEM's directional components can possibly be used as an alternative. In Euiseong-gun area where Sindong Group and Mayans Group are mainly distributed, geological lineaments trending $N5^{\circ}$~$10^{\circ}$W are dominant, while those of $N55^{\circ}$~$65^{\circ}$ W are major trends in Cheongsong-gun area where Hayang Group, Yucheon Group and Bulguksa Granite are distributed. Using relief shadowed DEM as an auxiliary data, we found the $N55^{\circ}$~$65^{\circ}$ W lineaments which are not cleanly observed in TM image over Euiseong-gun area. Compared with the trend of Gumchon and Gaum strike-slip faults, these lineaments are considered to be an extension of the faults. Therefore these strike-slip faults possibly extend up to Sindong Group in the northwest parts in the study area.

• The Journal of the Petrological Society of Korea
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• v.19 no.1
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• pp.1-18
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• 2010

On the ArcGIS 9.2 program in Gyeongsangbug-Do and Daegu areas, distribution ratios of rock types and geologic ages were obtained from the 1 : 250,000 scaled digital geologic and geomorphic maps. The obtained distribution ratios here will be used the geologic information data for industrialization and development planning of rock resources. The Gyeongsangbug-Do area consists of 86 rock types that can be divided into 10 large groups in geologic age. Their geologic distribution ratios show the decreasing in the order of Cretaceous, Precambrian, Jurassic, Quaternary, Age-unknown and Tertiary, all of which occupy the prevailing ratio of 96.30% in the area. Of which, sixteen rock types are somewhat dominant ones (64.04%). They are of Precambrian Yulri group and granite gneiss of the Yeongnam metamorphic complex and biotite gneiss of the Sobaegsan metamorphic complex, Age-unknown granite, Jurassic granite, Cretaceous Gasongdong and Dogyedong formations of the Yeongyang sub-basin, Nagdong and Chunsan formations and intermediate-basic volcanics of Euiseong sub-basin, Jinju and Jindong formations and andesite-andesitic tuff of Milyang sub-basin, and hornblende granite, and Quaternary alluvium. They show relatively narrow ranges of 2.07-6.53% in geologic distribution in exception of Jurassic granite showing 13.14%. And the rest 70 rock types appear to very narrow range between 0.01 and 1.94 %. On the other hand, twelve rock types are developed in the Daegu area. Their geologic ages appear to be classified into Cretaceous and Quaternary occupying 86.05% and 11.39%, respectively. Seven rock types take possession of 94.04% among the all rocks. The major rock types are Jinju formation of the Sindong group, Chilgog, Haman and Jindong formations of the Hayang group, andesite and andesitic tuff, hornblende granite and Quaternary alluvium. With exception of andesite and andesitic tuff of 37.40%, the types show slightly wide range of 3.25-17.39%, which apparently differ trends from that of Gyeongsangbug-Do area. And the rest of rock types have narrow ranges of 0.22-1.81% in the Daegu area.

• The Journal of the Petrological Society of Korea
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• v.9 no.3
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• pp.187-203
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• 2000

Mafic microgranular enclaves (MME) occur in the granites from the Bohyunsan area. The host granites are generally of granodioritic and granitic compositions. The MME can be divided into magic mineral clusters, quartz diorite and diorite according to their occurrence. Halter variation diagrams show linear trends between the MME and the host granites. Though the rim compositions of plagioclase in the host granites and the MME are similar the core compositions of plagioclase in some host granites show abnormally high An content. The Mg/(Mg+Fe) ratio of hornblende in the host granites gradually increase from the core to the rim. The chemical composition of minerals in the host granites had been affected by more marc magma composition. The modelling of major elements of the MME and hybrid host granites also indicate that they result from simple mingling/mixing between a dioritic magma and the host granite magma. The MME are thus interpreted to be globules of a more mafic magma which intruded the granite magma. Partial equilibration has been achieved between the MME and the host granites after they were commingled with each other.

• Korean Journal of Heritage: History & Science
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• v.46 no.1
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• pp.268-289
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• 2013

The Dinosaur tracksite at Jeori, Geumseongmyeon, Euiseonggun, Gyeongsangbukdo, Korea (National Monument No. 373) has been studied in the aspects of location, stratigraphy, sedimentology, fossil occurrence, unique geological records, literature, significance in natural history, preservation, and management. On the basis of these features, the Jeori tracksite has been assessed semiquantitavely. The Jeori tracksite occurs in the Sagok Formation (Albian) of the Euiseong sub-basin, and over 300 footprints forming 12 sauropod trackways, 10 ornithopod trackways, and 1 theropod trackways are preserved in this tracksite. The track-bearing deposits consist of tabular-bedded medium- to fine-grained arkose with mudstone drape, interlaminated fine-grained sandstone to siltstone and mudstone, and shaly mudstone. The dinosaur tracks are preserved in the interlaminated fine-grained sandstone to siltstone and mudstone, and most of them are observed as underprints. The track-bearing deposits are interpreted as sheetflood deposits on the floodplain under a seasonal paleoclimatic condition with alternating of wetting and drying periods. Multiple tension fractures with NE strike were formed in the track-bearing bed, which resulted in that tracks seem to occur in several horizons. The significance in natural history of the tracksite can be summarized as follows: 1) the historical implication of the Jeori tracksite as the firstly designated National Monument of dinosaur fossil sites, 2) the high density of the occurrence of diverse footprints (over 300) within small area (about $1,600m^2$), and 3) the significance of the tension fractures associated with the track-bearing bed as geoeducational records for the understanding the development of fault. In order to share the value of the Jeori tracksite in the aspect of natural history with the community and public, the interpretive panel should be modified to include figures explaining paleoenvironment and tension fault development. In addition it is recommended that a brochure be published briefly explaining the tracksite and to educate the residents about the natural and social significance of the tracksite. For the safety of visitors it would be desirable for the road in front of the tracksite to be moved at least 10 m southward, which could mitigate the shaking of the track bed caused by traffic.