• Title/Summary/Keyword: K feldspar

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Mineral Distribution in the Southeastern Yellow Sea Surface Sediments; KORDI Cruise Samples in 2010 (황해 남동부 표층 해양 퇴적물의 광물 분포; 2010년 한국해양연구원 탐사 시료)

  • Cho, Hyen-Goo;Kim, Soon-Oh;Yi, Hi-Il;Shin, Kyung-Hoon
    • Journal of the Mineralogical Society of Korea
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    • v.24 no.3
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    • pp.205-216
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    • 2011
  • Mineral compositions of 69 southeastern Yellow Sea surface sediments collected at the Korea Ocean Research and Development Institute (KORDI) cruise in 2010, were determined using the quantitative X-ray diffraction analysis. Southeastern Yellow Sea surface sediments are composed of major minerals (quartz 49.1%, plagioclase 13.0% and alkali feldspar 9.3%), clay minerals, calcite, and aragonite. Illite (9.4%) is the most abundant clay mineral, chlorite (4.6%) is the second, and kaolinite (0.8%) is few. Quartz and alkali feldspar contents are high in coarse-grained sediments, whereas amphibole and clay mineral contents are high in fine-grained sediments. Quartz, plagioclase, alkali feldspar, chlorite, and kaolinite contents are higher, and illite content is lower in mud zone 1 corresponding to south margin of Central Yellow Sea Mud than in mud zone 2, a part of Southeastern Yellow Sea Mud. Difference of mineral composition between two mud zone suggests that source of fine sediment may be different in two mud zone and Southeastern Yellow Sea Mud might be largely supplied from the Keum and Youngsan rivers in southern part of the west coast in the Korean Peninsula.

Geochemical and Stable Isotopic Studies of the Hwacheon Granite (화천 화강암에 대한 지화학 및 안정동위원소 연구)

  • Gyun, Go-Bo;Park, Yeong-Rok
    • Proceedings of the KSEEG Conference
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    • 2003.04a
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    • pp.189-190
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    • 2003
  • Oxygen and hydrogen isotopic data of whole rocks and mineral separates generally provide constraints on the nature of hydrothermal systems. We here report preliminary results of analyses of samples taken from the peraluminous granitic rocks and banded gneiss country rocks in Hwacheon area. Oxygen isotopic values for quartz and feldspar separates from the granitoids in Hwacheon area range from 8.2 to 10.6$\textperthousand$ and 5.8 to 8.5$\textperthousand$, respectively. (omitted)

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Geological Characteristics of Kyongju-Ulsan Area : Palaeomagnetism and Magnetic Susceptibility of the Granitic Rocks in the Ulsan Fault Area (경주-울산일원에 대한 지역지질 특성연구 : 울산단층주변 화강암류의 잔류자기와 대자율)

  • Kim, In-Soo;Son, Moon;Jung, Hyun-Jung;Lee, Joon-Dong;Kim, Jeong-Jin;Paik, In Sung
    • Economic and Environmental Geology
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    • v.31 no.1
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    • pp.31-43
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    • 1998
  • A total of 469 granitic samples were collected from 44 sites in the Ulsan fault area, southeast Korea. According to the previous petrographic studies, the granitic rocks have been divided into four groups (Hornblende biotite granodiorite, Hornblende granite, Biotite granite and Alkali-feldspar granite). NRM intensities, values of low field magnetic susceptibility, and magnetic behaviors during stepwise demagnetization experiments suggest rather a three-fold classification: In this scheme, Hornblende granite and Biotite granite are grouped together, as they did not show any significant differences in magnetic characteristics. Based on the Ishihara (1979)'s criterion, Alkali-feldspar granite is classified as ilmenite-series granite, whereas others are classified as magnetite-series granite. In the eastern part of the study area including the Tertiary basin area, declinations of site-mean characteristic remanent magnetizations (ChRMs) show clockwise deflection of more than 30 from the reference direction of east Asia. Both along and in the adjacent region of the Ulsan fault-line, however, no deflection of remanent direction was observed. A boundary line between the deflected and undeflected site-mean ChRMs is defined in this study, which runs roughly parallel to the Ulsan fault-line at the distance of about 6km eastward from the fault-line. We suggest that this newly found boundary line, which we call Yonil tectonic line, released dextral simple shear stress acted in the southeastern part of the Korean peninsula during the opening stage of the East Sea in the Early Cenozoic.

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Petrology, Geochemistry and Tectonic Implication of the A-type Daegang granite in the Namwon area, Southwestern part of the Korean Peninsula (한반도 남서부 남원 일대에 분포하는 A형 대강 화강암의 암석학, 지화학 및 지구조적 의미)

  • Kim, Yong-Jun;Cho, Deung-Lyong;Lee, Chang-Shin
    • Economic and Environmental Geology
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    • v.31 no.5
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    • pp.399-413
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    • 1998
  • Daegang granite is located around the Namwon-gun, Cheolabuk-do, and is an elongate stock $(80 km^{2})$ in the NNE-SSW direction. Daegang granite has the very same mineralogical and geochemical characteristics as those of the typical A-type granites; (1) it is a one feldspar hypersolvus granite, and is classified as an alkali feldspar granite in the lUGS scheme, (2) has small amounts of Fe-rich biotite (annite) and alkali amphibole (ribeckite) that are late in the crystallization sequence of the granitic magma, (3) always contains opaque oxides, fluorite and zircon, (4) shows high and quite homogeneous $SiO_2$, content (mostly 72~77 wt.%) and $(Na_{2}O+K_{2}O)/Al_{2}O_{3}$ ratio (0.90~0.98), (5) contains high Ga, lOOOO*Ga/Ai, $K_{2}O+Na_{2}O$, $(K_{2}O+Na_{2}O)/CaO$, $K_{2}O/MgO$, FeO/MgO, agpaitic index, Zr, Nb, Ce, Y, Zn value or ratio that resemble to those of the Australian A-type granites (Whalen et al., 1987), and (6) has enriched LREE and HREE that show flat variation pattern with slightly depleted in HREE and profound Eu anomalies (Eu/Eu*=0.04~0.l4). In the tectonic discrimination diagrams of Pearce et al. (1984) and Eby (1992), Daegang granite is classified as a within plate granite and $A_{2}-type$.

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Geochronology and Petrochemistry of Foliated Granites between Damyang and Jinan (담양(潭陽)-진안(鎭安)사이에 분포(分布)하는 엽리상화강암류(葉理狀花崗岩類)에 대(對)한 지질시대(地質時代)와 성인(成因)에 관(關)한 연구(硏究))

  • Kim, Cheong Bin;Kim, Yong Jun
    • Economic and Environmental Geology
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    • v.23 no.2
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    • pp.233-244
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    • 1990
  • Plutons of Damyang-Jinan area consist of gray feldspar granite gneiss, biotite granite gneiss, foliated granites, Namweon granites, gabbro, biotite granite and Ogangri granite in term of mineralogical, texture and field evidence. From Isotope data of study area, chronological order of the Plutons are the Pre-cambrian gray feldspar granite gneiss(Ar39-Ar40, hornblende, $1998.4{\pm}8.3Ma$), middle to late Triassic Daegang foliated granite(Rb/Sr, whole rock, $288{\pm}4Ma$), foliated hornblende biotite granodiorite(K/Ar, hornblende, $198.7{\pm}9.9Ma$), Sunchang foliated granodiorite(Rb/Sr, whole rock, $222{\pm}4Ma$), foliated two mica granite, Samori foliated granite and Namweon granite(Rb/Sr, whole rock, $211{\pm}3Ma$: K/Ar, hornblende, $203{\pm}10.2Ma$), middle Jurassic Gabbro(K/Ar, hornblende, $180.7{\pm}9MA$) and biotite granite, and Cretaceous Ogangri granite. According to variations diagrams of $Al_2O_3$ versus normative PI(100 An)/(Ab+An), Daegang foliated granite is plotted on tholeiitic series, and other foliated granites on calc alkaline rock series which are consider to be formed by magmatism at continental margin and island arc region. And alkalinity versus $SiO_2$ shows that Daegang folited granite and Samori foliated granite are correspond to alkaline region, foliated hornblende biotite granodiorite and Sunchang foliated granodiorite to calc alkaline region, and foliated two mica granite to both regions. According to ACF diagrams, Daegang and Samori foliated granites are plotted on S-type. Foliated hornblende biotite granodiorite and Sunchang foliated granodiorite on I-type, and foliated two mica granite on both type. Foliated granites are a series of differentiated products from cogenetic magma, and effected under ductile sheared zone. Characteristic foliation of foliated granites are considered to be generated by dextral strike slip faulting and ductile shearing.

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Mineralogical Properties of Asian Dust in April 6 and 15, 2018, Korea (2018년 4월 6일과 15일 황사의 광물학적 특성)

  • Jeong, Gi Young
    • Journal of the Mineralogical Society of Korea
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    • v.31 no.2
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    • pp.103-111
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    • 2018
  • Mineralogical properties of two Asian dust (Hwangsa) samples collected during dust events in April 6 and 15, 2018 were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD analyses showed that Asian dusts were dominated by phyllosilicates (62 wt%) comprising illite-smectite series clay minerals (ISCMs) (55%), chlorite (3%) and kaolinite (4%). Nonphyllosilicate minerals were quartz (18%), plagioclase (9%), K-feldspar (3%), calcite (3%), and gypsum (2-4%). Mineral compositions determined by SEM chemical analyses were consistent with XRD data. ISCMs occur as submicron grains forming aggregate particles or coating coarse mineral grains such as quartz, plagioclase, K-feldspar, chlorite, and calcite. The ISCMs are often associated with calcite nanofibers and gypsum blades. Mineralogical properties of 2018 dusts were similar to those of previous dusts although clay contents were higher than that of coarse 2012 dust.

Origin of Sangumburi, Jeju Island (제주도 산굼부리의 성인)

  • Kil, Youngwoo;Yun, Sung-Hyo;Lee, Moon Won;Yang, Kyounghee;Seol, Junghwan
    • The Journal of the Petrological Society of Korea
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    • v.25 no.3
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    • pp.283-298
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    • 2016
  • Sangumburi crater, designated as Natural Monument No. 63, recognized as a maar, but precise geological mapping and geological characteristics in the field indicate that Sangumburi crater is a pit crater. Two stages of volcanic activities created Sangumburi pit crater. Lava flow (aphanitic pyroxene basalt I) and associated pyroclastic deposit (pyroclast I), composed of ash and lapilli, were formed at the stage 1. In the stage 2, lava flow (feldspar olivine basalt) was overlain by lava flow (aphanitic pyroxene basalt II) and associated pyroclastic deposit (pyroclast II), composed of agglomerate. Sangumburi pit crater formed at $0.073{\pm}0.036Ma$, determined by Ar-Ar age dating for the feldspar olivine basalt at the stage 2. It is not clear the preferred migration direction of subsurface magma after Sangumburi pit crater formed.

Correlation analysis between Engineering properties and mineralogy of clay sediments in New Busan Port area of the estuary of the Nakdong River (낙동강 유역 신항만부지 지역 점토 퇴적물의 광물조성과 토질특성의 상관성)

  • Lee, Son-Kap;Hwang, Jin-Yun;Chung, Seong-Gyo;Kim, Sung-Wook
    • Proceedings of the Korean Geotechical Society Conference
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    • 2004.03b
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    • pp.483-490
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    • 2004
  • Nakdong River Plain and its adjoining sea arc unusually covered by very thick soft clay sediments which were caned Pusan clays, sometimes reaching 40-70m. Since early 1990s a large number of geotechnical investigations have been carried out for land reclamation works in the area, including Busan city and its neighboring cities. Nevertheless, geotechnical engineers have paid little attention to studying geological characteristics on the clays, except some researches related to mineralogy, geo-chemistry, benthic foraminiferal fauna etc. The purpose of reserach is the knowledge of the correlation between engineering properties and mineralogy of clay sediments. The correlation analysis carry out multiple regression that have independent variables (Engineering properties) and dependent variables (mineralogy, geochemistry). Engineering properties of clay are correlated with the mineral compositions and geochemical characteristics. The result of the analysis is Wn = -0,6Feldspar + 1.1pH + 0.01TDS + 27.5, Ip = 0.36Clay + 1.44Vermiculite + 0.94clay mineral - 22.118, PI. = 0.005TDS - 0.31Feldspar + 22.43, eo = 0.02Vermiculite - 0.01Quartz + TDS + 0.93, ${\nu}$t = 0.009Quartz - 0.06Conductivity + 1.67, E50 = 1.94Vermicuhte - 0.96Kaohnite -0.53silt + 49.64, SR = -0.25Kaolinite + 1.5pH -2.3Conductivity, Cc = 0.03pH + TDS -0.2, LL = 0.5Clay + 1.3Vermiculite + 5.5Conductivity + 0.8Caly mineral -20.48

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An Exploratory Study on the Geometrical Reconstruction of the Late Cretaceous Misiryeong Laccolith and the Lost Size of the Baekdam Basin (백악기 후기 미시령 병반의 기하학적 복원과 백담분지의 규모에 관한 소고)

  • Chwae, Uee-Chan;Kim, You-Bong;Suzuki, Kazuhiro;Choi, Sung-Ja
    • Economic and Environmental Geology
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    • v.44 no.4
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    • pp.321-327
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    • 2011
  • As a product of geological mapping of the Changamjeom Sheet (1:50,000) located around Misiryeong at a distance towards the west from Sokcho city, a small laccolith of hypabyssal rocks has been geometrically reconstructed to understand the original laccolith shape using structural contour lines of random spot sediments laid on the quartz feldspar porphyry and a schematic cross section. The laccolith age is constrained to ca. $84.4{\pm}1.8$ Ma (SHRIMP). The originated Baekdam sedimentary basin with the lost size has been yielded to 6 km wide and 16 km long.

Geochemistry of Main Gangue Minerals at the Sangdong Tungsten Deposit (상동(上東) 중석광상(重石鑛床)의 주맥석(主脈石) 광물(鑛物)에 대(對)한 지화학(地化學))

  • Moon, Kun Joo
    • Economic and Environmental Geology
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    • v.17 no.2
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    • pp.79-90
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    • 1984
  • Microprobe analyses have disclosed geochemical compositions of the main components such as garnet, pyroxene, amphibole, chlorite, biotite, and muscovite in the Sangdong W skarn deposit and this study has identified several minerals which were previously unrecorded from this deposit; they are scapolite, zeolite, K-feldspar, rutile. illite and apophyllite. The $Fe^{+3}/Fe^{+2}$ or Mg/(Mg+Fe) ratios of coexisting minerals represents that these minerals were partially in equilibrium.

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