• 제목/요약/키워드: continental margin

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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) (Geochronology and Petrochemistry of Foliated Granites between Damyang and Jinan)

  • 김정빈;김용준
    • 자원환경지질
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    • 제23권2호
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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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완도지역(莞島地域)에 분포하는 미문상화강암(微文象花崗岩)에 대한 암석화학적(岩石化學的) 연구(硏究) (Petrochemical Study on the Micrographic Granite in the Wando Area)

  • 신인현;남기상;김희남;박영석;안건상
    • 자원환경지질
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    • 제27권2호
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    • pp.181-190
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    • 1994
  • Petrochemical study on the micrographic granite distributed in the Wando area, the southernmost part of the Yeongdong-Kwangju depression is performed to investigate the petrogenesis and differentiation processes of the granitic magma. Polarized light microscopy for modal analyses, electron probe microanalyses of feldspars and biotite, inductively coupled plasma analyses for major and trace element contents were adopted in the study. The lithology of the study area consists of Precambrian metasediments, Mesozoic volcanic and sedimentary rocks, and micrographic granite which intrude into the former. The micrographic granite in the Wando area are distributed in the shape of a cauldron. Modal and nonnative mineral analyses of the micrographic granite fall in the area of granite and granodiorite. The chemical composition indicates that the micrographic granite is I-type and magnetite series. The micrographic granite is characterized by more than 90% of micrographic texture in volume percent. Feldspars in the micrographic granite is alkali feldspars (Or, 45~93) and plagioclases (albite to oligoclase). The biotite has a intermediate composition between phlogopite and annite solid solution. The results of the petrochemical studies indicate that the granitic magma of calc-alkaline source materials reactivated in a compressional environment at the continental margin, and then was differentiated by fractional crystallization. The micrographic granite intruded into a shallow level of the crust (5~7 km) in the late Cretaceous.

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충주지역 희토류 광상의 성인: 산출상태와 지화학적 특성 (Genesis of the REE Ore Deposits, Chungju District, Korea: Occurrence Features and Geochemical Characteristics)

  • 박맹언;김근수
    • 자원환경지질
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    • 제28권6호
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    • pp.599-612
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    • 1995
  • Some REE ore deposits are located in the middle part the of Korean peninsula. Geotectonically, the REE ore deposits situated on the Kyemyeongsan Formation of northern margin of the Okcheon geosynclinal belt and in the transitional zone between Kyeonggi massif and the Okcheon belt, with a deep-seated fracture separating the two tectonic units. The Kyemyeongsan Formation are different in lithology and metamorphic grade from the Gyeonggi massif and the Okcheon super group. The sequence of Kyemyeongsan Formation is dominantly composed of acidic metavolcanic and volcaniclastic rocks associated with alkaline igneous rocks which are related to volcano-plutonism. The REE ore deposits contain mainly Ce-La, Ta-Nb, Y, Y-Nd and Nd-Th group minerals. More than 15 RE and REE minerals have been found in the deposits, such as allanite, fergusonite, thorite bestnaesite, euxenite, polyclase, monazite, columbite, (Nb)-rutile, okanoganite, sphene, zircon, illmenite and some other unknown minerals. According to the characteristics of the mineral association, the REE ore deposits may be divided into 4 ore types; Zircon-REE, allanite-REE, feldspar-REE and fluorite-REE type. The Sm-Nd isochron age of the REE ore is 330 Ma, and the Sm-Nd model age is 1.11 Ga with ${\varepsilon}_{Nd(t)}$ being - 2.9. This data suggest that the REE ore deposit was formed in the early Carboniferous, and the ore-forming material came from the mantle. The REE ores show distinct light REE enrichment with strong negative Eu anomaly. The REE patterns of schistose rocks from Kyemyeongsan Formation are similar to felsic volcanics from rifts or back arc basins in or near continental crust. The genesis of the REE ore deposit is quite complicated. Different geologic processes are displayed in the studied area; sedimentation, volcanic activity, metamorphism and hydrothermal replacement. Alkali granite has suffered extensive post-magmatic metasomatism of a high temperature to produce alkali metasomatites. Geochemical charateristics show that metasomatism of alkaline fluid was probably the dominant ore-forming process in Chungju district.

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담양(潭陽)-진안(鎭安)사이에 분포(分布)하는 엽리상화강암류(葉理狀花崗岩類)에 대(對)한 암석화학적(岩石化學的) 연구(硏究) (Geochemical Study on Foliated Granites in the Damyang-Jinan area)

  • 김정빈;김용준;홍세선
    • 자원환경지질
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    • 제23권1호
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    • pp.87-104
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    • 1990
  • Foliated granites between Damyang and Jinan are subdivided into Daegang foliated granite, Foliated hornblende biotite granodiorite, Sunchang foliated granodiorite, Foliated two mica granite and Samori foliated granite by mineral and texture. From EPMA data of the foliated granites following results are achieved. Composition of plagioclase are correspond to andesine, oligoclase and albite in Foliated hornblende biotite granodiorite, Sunchang foliated granodiorite and other foliated granites, respectively. And amphiboles are calcic hornblende in Foliated hornblende biotite granodiorite, and riebeckite in Daegang foliated granite. In differentiation index(D. I.) and Larsen index(L. I.), Daegang foliated granite, Foliated two mica granite and Samori foliated granite which belong to granite are 83.12-95.54 and 25.86-29.05 and Foliated hornblende biotite granodiorite and Sunchang foliated granodiorite of diorite to granodiorite are 54.99-78.54(D. I.) and 6.48-21.01(L. I.). Harker and AMF diagrams plotted from foliated granites show that the granites are product of calc alkali rock series orignated from co-magma. Characteristic foliation of foliated granites fromed by ductile deformation at deep zone of dextral strike slip fault. Foliated granites are considered as a series of differentiated product of Triassic Igneous activity of Songrim disturbance. According to REE, (La/Lu) and Eu/Sm, Foliated hornblende biotite granodiorite and Sunchang foliated granodiorite are correspond to granodiorite, and other foliated granites are monzo-and syeno-granite. Foliated granites having 0.20-0.01 of Em/Sm ratio are plutons emplaced by the tectonic setting in continents and continental margin.

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ArcGP 자료를 이용한 북극 스발바드 군도의 중력특성 (A Gravity Characteristic of Svalbard Archipelago in Arctic by Using ArcGP Data)

  • 유상훈;김창환;황종선;민경덕
    • 한국지구물리탐사학회:학술대회논문집
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    • 한국지구물리탐사학회 2005년도 공동학술대회 논문집
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    • pp.255-260
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    • 2005
  • ArcGP 중력자료를 이용하여 다산과학기지가 위치한 북극 스발바드 군도의 중력 특성을 살펴보았다. 지형자료와 유사한 형태로 분포하는 free-air 중력이상에서 보이던 비활성 대륙 연변부의 가장자리 효과는 부게보정 후 보이지 않고, 육상지역의 GTOPO30 지형자료를 이용한 지형보정을 거친 완전 부게 중력이상에서 육상지역에서 해양지역으로 갈수록 중력이상이 증가하는 즉, 모호면의 상승과 관련이 깊은 특성이 관찰된다. 지형으로부터 산출된 중력치와 free-air 중력이상과의 상관관계를 볼 때, 육상지역이 해양지역에 비해 지각평형이 다소 덜 이루어진 것으로 파악되며, 파워스펙트럼 분석을 통해 결정된 절단파수를 이용한 필터링 후 계산된 잔여이상에서 육상지역의 단층대를 따라 발달하는 특징적인 고이상대와 두꺼운 퇴적층에서 기인한 저이상대가 보이고 있다. 또한, 해양지역 대륙사면의 최하부에서 기반 함몰 내지는 기반암 상부의 두꺼운 퇴적층과 관련이 있는 저이상대가 발달하고 있다.

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남한의 백악기-제3기초 화강암과 마그마 혼합 : 시공간적 변화와 지구조적 의미(다중 슬랩 윈도우 모델) (Cretaceous to Early Tertiary Granites and Magma Mixing in South Korea : Their Spatio-temporal Variations and Tectonic Implications (Multiple Slab Window Model))

  • 김종선;김건기;좌용주;손문
    • 암석학회지
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    • 제21권2호
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    • pp.203-216
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    • 2012
  • 한반도 남부의 백악기-제3기초 화강암의 암석학적 특징과 연대측정 자료들을 종합하여 시공간적 변화를 반영하는 지구조 모델을 제안하고자 하였다. 여러 암석기재와 지화학적 연구결과로부터 이들 화강암류는 대륙 연변부에서 해양지각의 섭입에 의해 형성된 마그마 기원으로 지각 천처에서 정치된 특징을 보인다. 또한 화강암류 내에는 고화과정 중 맨틀에서 유래한 염기성 마그마의 주입에 의한 마그마 혼합을 지시하는 다양한 형태와 크기의 MME들이 분포한다. MME의 분포와 화강암의 연령자료를 함께 살펴보면 시공간적으로 일정한 시기의 것들이 일정한 지역에 한정되어 분포하는 양상을 보인다. 이러한 특징은 후기 백악기의 이자나기-태평양판의 해령섭입으로 인한 다중 슬랩 윈도우 모델에 의해 설명될 수 있다.

한반도 서남부에 분포하는 중성-염기성 심성암류에 대한 암석학적 연구 (Petrological Study on the Intermediate-basic Plutonic Rocks in the Southwestern Part of the Korean Peninsula)

  • 김용준;박재봉;박병규
    • 한국지구과학회지
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    • 제27권5호
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    • pp.528-538
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    • 2006
  • 이 연구의 목적은 한반도 서남부에 분포하는 중성-염기성 심성암류의 지화학적 특성과 성인을 밝히는데 있다. 이들 중성-염기성암류는 주로 선캠브리아기의 회장암-반려암, 트라이아스기의 각섬석반려암(지리산 지역), 쥬라기의 섬록암-섬장암(지리산 지역과 북부 지역) 그리고 백악기 반려암-섬록암(남부 지역)으로 구성되어 있다. 암괴형의 회장암은 많은 관입체로 구성되어 있으며 반려암-노라이트-트록토라이트와 우백질 반려암으로 이루어진 반려암질암에 의해 관입되어 있다. 주 성분-미량 성분의 변화도, AMF 삼각도와 Pl-Px-Ol 삼각도에서, 우리는 한반도 서남부에 분포하는 중성-염기성암류가 Daly의 값과 유사한 경향을 보이며 칼크-알카리질암류에 속함을 보여준다. REE (La/Yb)cw와 Eu/Sm 값에 따르면 이들 암류는 경희토류가 중희토류보다 부화되어 있으며, 이는 대륙 연변부의 지구조에서 정치한 화성암류의 특징이다.

Local Seismic Activity around the Lützow-Holm Bay, East Antarctica

  • Kaminuma, Katsutada;Kanao, Masaki
    • Ocean and Polar Research
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    • 제26권3호
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    • pp.523-529
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    • 2004
  • The seismic monitoring at Syowa Station$(69^{\circ}S,\;39^{\circ}E: SYO)$, located on the continental margin of the Eastern Dronning Maud Land, East Antarctica, began in 1959. Phase readings of the earthquakes have been reported since 1967 and have been annually published as part of the Data Report Series of the National Institute of Polar Research since 1968. An observation of a tripartite seismic network was carried out at SYO for a period of three years from 1987 to 1990. Epicenters of local earthquakes were determined for the first time by using the array network for the three-year period. Many different types of earthquakes, such as the mainshock-aftershock type, twin earthquake, earthquake swarms, etc., were detected during the period. After this, local events around SYO have been detected empirically from their waveforms recorded on seismograms. The seismic activity for the period of 1987-1990 was higher than that of the following decade. Earthquake epicenters, occurring during that period, were highly localized along the coast and in the central part of the $L\"{u}tzow-Holm$ Bay (LHB). Nine local earthquakes, recorded during the period of 1990-1996, showed many different types of events. The seismicity for the period of 1990-1996 was very low and the magnitudes ranged from 0.1 to 1.4. The locations of some events were determined by using the single station method for SYO, i.e., using the particle motions of the initial phase and S-P time. Two local events were detected in 1998 and one event in 2001. It would be estimated that the stress concentration was related to the glacial rebound around the LHB. Afterwards, we will be able to eventually examine the relationship between the seismicity around Antarctica and deglacial phenomena such as crustal uplift, and sea level change within the earth environmental system.

옥천지향사대(沃川地向斜帶) 동남대(東南帶)에서의 화성활동(火成活動)(III)(나주(羅州)-남창지역(南倉地域)을 중심(中心)으로) (The study on the Igneous Activity in the Southeastern Zone(SE-zone) of the Ogcheon Geosynclinal Belt,Korea(III) (with the Igneous Activity between Naju and Namchang Area))

  • 김용준;박영석;주승환;오민수;박재봉
    • 자원환경지질
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    • 제24권3호
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    • pp.261-276
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    • 1991
  • The main aspect of this study are to clarify igneous activity of igneous rocks, which is a member of various intrusives and volcanics exposed in Naju-Namchang area of southern central zone of Ogcheon Geosynclinal Belt, southern part of Youngdong-Kwangju depression zone of tectonic provinces in Korea. Naju-Namchang area are subdivided into three rock belts based on occuring of Cretaceous granites. Three rock belts consist of foliated granites, Jurassic granites and Cretaceous granites in central granitic rock belt (C-C), and acidic tuff and lavas in northwest volcanic rock belt(C-NW) and southeast volcanic rock belt(C-SE). Chemical composition of these igneous rocks show mostly similar trend to the Daly's values on Harker diagram and correspond to VAG + Syn-COLG region on Pearce's discrimination diagram. These igneous rocks vary wide range in total REE amount(37.4-221.3ppm) characterized by enriched LREE content and steep negative slope in Eu(-) anomaly. It is concluded each synchronous granites which composed of serveral rock facies is considered to formed by differentiation of co-magma at continental margin, and igneous activity of study area are two more Pre-Cambrian Orogenies, Songrim Disturbance, Daebo Orogeny and Bulkuksa Disturbance.

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한반도 남서부지역에 분포하는 백악기 화강암류에 대한 지화학적 연구 (Geochemical Study of the Cretaceous Granitic Rocks in Southwestern Part of the Korean Peninsula)

  • 위수민;박세미;최선규;유인창
    • 자원환경지질
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    • 제38권2호
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    • pp.113-127
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    • 2005
  • 한반도 남서부 지역은 고태평양판의 섭입에 의한 화성활동이 매우 활발했던 지역으로 백악기 화강암류와 이와 성인적으로 밀접한 관련이 있는 것으로 추정되는 화산암이 넓게 분포하고 있다. 백악기 화강암류를 형성시킨 마그마의 특성 및 지구조적 환경을 규명하고자 이미 보고 된 185개의 자료와, 야외 지질 조사를 통해 얻은 시료 중 신선한 36개의 시료에 대해 주성분 원소, 미량원소에 대한 지화학 분석을 실시하였다. 본 역 화강암류들은 전형적으로 I-type의 비알칼리암 중 칼크-알칼리 계열에 속하며 ANK vs. ACNK도에 도시해볼 때 대부분 메타알루미나질에 해당된다. 주성분 및 미량원소의 변화경향은 일반적인 화강암류의 분화경향과 유사하지만 지역별 주성분 및 미량원소의 특성을 살펴보면 이들 화강암류가 동원마그마 기원이 아님을 시사한다. 연구 지역의 동쪽에 분포하는 화강암체들은 서부에 비해 높은 Li, Co, Sr Sc의 함량과 낮은 Rb, Nb의 함량을 나타낸다. 미량원소의 함량은 화강암의 세계 평균값보다 전반적으로 높게 나타나는 경향이 있으며, 특히 Cr, Co, Ni, V, Sc등의 철-마그네슘 계열 원소의 함량이 더 높게 나타났다. 희토류원소는 모두 LREE가 HREE 보다 부화되어 화강암류의 전형적인 패턴과 일치하며, 서부 지역이 동부 지역보다 더 뚜렷한 Eu(-)이상을 갖는다. 지구조 판별도에서도 VAG와 syn-COLG 환경에 점시된다. 본 연구지역의 화강암류들은 대륙연변부에서 나타나는 화강암류의 희토류원소의 총량($60{\~}499ppm$)과 $(La/Lu)_{CN}=8.9{\~66}$의 범위에 해당되며 모든 지화학적 자료를 종합해보면 이지역의 화강암류들은 고태평양판의 섭입에 의한 압축장이 작용하는 대륙 연변부에서 생성되었음을 알 수 있다.