The Journal of the Petrological Society of Korea (암석학회지)

The Petrological Society of Korea (한국암석학회)
권호 표지

The Overview of Layered structures in Mafic - Ultramafic Macheon Intrusion

고철질-초고철질 마천관입암의 층상구조 개관

  • Song, Yong-Sun (Department of Environmental Geosciences, Pukyong National University) ;
  • Kim, Dong-Yeon (Department of Environmental Geosciences, Pukyong National University) ;
  • Park, Kye-Hun (Department of Environmental Geosciences, Pukyong National University)
  • 송용선 (부경대학교 환경지질과학과) ;
  • 김동연 (부경대학교 환경지질과학과) ;
  • 박계헌 (부경대학교 환경지질과학과)
  • Published : 2007.09.30
Download PDF
⟨ Previous Next ⟩

Abstract

Macheon Layered Intrusion (MLI) which intruded into Precambrian gneiss complex of the northern Jirisan area, southeastern part of Youngnam (or Sobaeksan) Massif, is a layered mafic-ultramafic complex of Triassic age (ca. 223 Ma). The MLI is divided into Layered Series and Laminated Series. Layered Series is subdivided into Central Zone (Lower Zone) consisting of olivine gabbros and Peripheral Zone (Middle or Upper Zone) consisting of hornblende gabbros based on the type of cumulus texture and the main mafic phase. The Central Zone of Layered Series comprises thinly laminated olivine gabbros and uniform or thickly laminated coarse olivine gabbros which consist of mela-gabbro, troctolite, leuco-troctolite, and anorthositic rocks. Laminated Series is also subdivided into quartz-bearing biotite-pyroxene gabbros and homblende diorite and both have variable amount of interstitial quartz and microcline. Laminated series display moderately to slightly developed igneous lamination which is defined by the planar alignment of lath-shape plagioclases. Chilled margin of quartz-bearing biotite-pyroxene gabbro with surrounding Precambrian gneisses insists shallower intrusion of more felsic cognate magma evolved in the deep a little later. Rocks of Layered Series have orthocumulus to adcumulus olivine, adcumulus to intercumulus plagioclase, and intercumulus to heteradcumulus pyroxene and hornblende. Magmatic modally grading, folding, and cross-lamination are not rarely occurred in thinly layered rocks. These textural characteristics define main mechanisms of the formation of layered and laminated structure in mafic-ultramafic rocks of Macheon Layered Intrusion are gravity settling and in-situ crystallization associated with slumping and density current.

영남(소백산)육괴의 남서부인 지리산지역의 북서부에 선캠브리아 편마암 복합체를 트라이아스기(약 223 Ma)에 관입한 마천층상관입암은 크게 층상계열과 엽상계열의 두 그룹으로 구분되는 고철질-초고철질 암석들로 구성되어 있으며, 마그마혼합의 특성을 잘 보이는 암맥상의 고철질 암이 수반된다. 층상계열은 누적조직의 특성과 주구성 유색광물의 종류에 의해 중앙부의 감람석 반려암대(하부대)와 주변부의 각섬석 반려암대(중 내지 상부대피 두 부분으로 다시 세분된다. 중앙부의 감람석 반려암은 비교적 얇은 우흑질과 우백질의 층들이 규칙적으로 교호된 중립질 반려암질 암과 균질하고 두꺼운 층상구조를 이룬 조립질 반려암질 암들이 서로 협재되어 있으며, 주구성 암종은 우흑질 반려암, 트록토라이트, 우백질 트록토라이트, 사장암질암 등으로 감람석과 사장석이 주구성 광물이다. 엽상계열은 함석영 흑운모휘석 반려암과 보다 분화된 특성의 각섬석 섬록암으로 분류되며 간극상로 산출되는 소량의 석영과 미사장석을 포함하고 있다 주변의 선캠브리아 편마암류와의 접촉대에 냉각대가 발달되어 있어 심부에서 보다 분화된 동원성 마그마가 어느 정도 시간적인 간격을 갖고 좀 더 냉각된 환경에서 관입한 것으로 보인다. 층상계열에 발달된 층상구조는 감람석은 주로 정누적구조 내지 부가누적구조, 사장석은 부가누적 내지 간극누적구조를 보이며, 단사휘석과 각섬석은 간극누적 내지 이형부가누적조직을 이루고 있다. 층상암들에서 마그마작용동안 생성된 습곡구조, 점이층리, 사층리 등이 드물지 않게 산출된다. 마천층상관입암체에 발달된 층상구조와 엽상구조가 주로 중력침전과 제자리 결정작용에 의해 생성되었으며 슬럼핑과 밀도류 흐름작용도 상당한 역할을 하였을 것으로 해석된다.

Keywords

References

  1. 김옥준, 홍만섭, 윤석규, 박희인, 박양대, 김기태, 이하영, 윤선, 1964, 한국지질도 운봉도폭설명서. 경상남도. 18p 25p
  2. 김옥준, 박희인, 1958, 산내니켈광상조사보문. 지질광상조사연구보고 제2호, 중앙지질광물연구소
  3. 송용선, 김동연, 박계헌, 정창식, 2004a, 마천 반려암질 층상관입암. 한국암석학회 한국광물학회 공동학술발표회 논문집. 36-38
  4. 송용선, 박계헌, 백인성, 2004b, 마천 반려암질 층상관입암에서 산출되는 크롬-스피넬: 진주층 퇴적물중의 쇄설성 크롬-스피넬의 기원지(provenance)로서의 기능성. 한국암석학회 한국광물학회 공동학술발표회 논문집. 39-41
  5. 박희인, 1958, 산내니켈광상시추조사보고서. 지질광상조사연구보고 제4호, 중앙지질광물연구소. 3-37
  6. 홍만섭, 1965, 지리산지역 지하자원 개발계획조사보고서. 건설부. 92p
  7. Boudreau, A.E., 1995, Crystal aging and the formation of fine-scale igneous layering. Mineral. Petrol., 54, 55-69 https://doi.org/10.1007/BF01162758
  8. Bowen, N.L., 1928, The Evolution of Igneous Rocks. Princeton, NJ. Princeton University Press, 332p
  9. Campbell, I.H., 1978, Some problems with the cumulus theory. Lithos. 11, 311-323 https://doi.org/10.1016/0024-4937(78)90038-5
  10. Campbell, I.H., Roeder, P.L. and Dixon, J.M., 1978, Plagioclase buoyancy in basaltic liquids as determined with a centrifuge furnace. Contrib. to Mineral. and Petrol., 67, 369-377 https://doi.org/10.1007/BF00383297
  11. Chen, C.F. and Turner, J.S., 1980, Crystallization in a double diffusive system. Jour. Geophys. Res., 85, 2573-2593 https://doi.org/10.1029/JB085iB05p02573
  12. Foley, J.P., Light, T.D., Nelson, S.W. and Harris, R.A., 1997, Mineral occurrences associated with mafic-ultramafic and related alkaline complexes in Alaska. Economic Geol. Monographs. 9, 396-449
  13. Higgins, M.D., 1998, Origin of anorthosite by textural coarsening: quantitative measurement of a natural sequence of textural development. Jour. Petrol., 39, 1307-1325 https://doi.org/10.1093/petrology/39.7.1307
  14. Hunter, R.H., 1996, Texture development in cumulate rocks. In: Layered Intrusions (ed. R.G. Cawthorn), Elsevier, 77-101
  15. Irvine, T.N., 1974, Petrology of the Duke Island ultramafic complex southeastern Alaska, Boulder, Co. Geol. Soc. Am. Mem. 138, 240p
  16. Irvine, T.N., 1980, Magmatic infiltration metasomatism, double-diffusive fractional crystallisation, and adcumulus growth in the Muskox and other layered intrusions. In: (ed. R.B. Hargraves) Physics of Magmatic Processes, Princeton University Press, Princeton, NJ, 325-383
  17. Irvine, T.N., 1987, Layering and related structures in the Duke Island and Skaergaard Intrusions: similarities, differences, and origins. In: Origins of Igneous Layering, Dordrecht (ed. I. Parsons), Reidel, 185-245
  18. Kim, C.B. and Turek, A., 1996, Advances in U-Pb zircon geochronology of Mesozoic plutonism in the southwestern part of Ryeongnam massif, Korea. Geochemical Jour., 30, 323-338 https://doi.org/10.2343/geochemj.30.323
  19. Lee, C.A., 1996, A review of mineralization in the Bushveld Complex and some other layered intrusions. In: Layered Intrusions (ed. R.G Cawthorn), Elsevier, 1-43
  20. Lesher and Walker, 1988, Cumulate maturation and melt migration in a temperature gradient. Jour. Geophys. Res. 93, 10295-10311 https://doi.org/10.1029/JB093iB09p10295
  21. Martin. D., 1990, Crystal settling and in situ crystallization in aqueous solutions and magma chambers. Earth Planet Sci. Lett. 96, 336-348 https://doi.org/10.1016/0012-821X(90)90011-L
  22. McBirney, A.R., 1985, Further considerations of double-diffusive stratification and layering in the Skaergaard Intrusion. Jour. Petrol. 26, 993-1001 https://doi.org/10.1093/petrology/26.4.993
  23. McBirney, A.R., 1996, The Skaergaard Intrusion. In: Layered Intrusions (ed. R.G. Cawthorn), Elsevier, 147-180
  24. McBirney, A.R. and Hunter, R.H., 1995, The cumulative paradigm reconsidered. Jour. Geol., 103, 114-122 https://doi.org/10.1086/629727
  25. McBirney, A.R. and Noyes, R.M., 1979, Crystallization and layering of the Skaergaard intrusion. Jour. Petrol., 20, 487-554 https://doi.org/10.1093/petrology/20.3.487
  26. Morse, S.A., 1973, The feldspar/magma density paradox. In: The Nain Anorthosite Project, Labrador: Field Report 1972. Amherst, MA (ed. S.A. Morse), University of Massachusetts at Amherst, 113-116
  27. Morse. S.A., 1986a, Thermal structure of crystallizing magma with two-phase convection. Geol. Mag. 123, 205-214 https://doi.org/10.1017/S0016756800034701
  28. Morse, S.A. 1986b, Convection in aid of adcumulus growth. Jour. Petrol. 27, 1183-1214 https://doi.org/10.1093/petrology/27.5.1183
  29. Mukherjee, A. and Das, S., 2002, The plagioclase-magma density paradox re-examined and the crystallization of Proterozoic anorthosites: a discussion. Jour. Petrol, 43, 1979-1983 https://doi.org/10.1093/petrology/43.10.1979
  30. Naslund and McBirney, 1996, Mechanism of formation of igneous layering. In: Layered Intrusions (ed. R.G. Cawthorn), Elsevier, 1-43
  31. Nicolas, A., 1992, Kinematics in magmatic rocks with special reference to gabbro. Jour. Petrol, 33, 891-915 https://doi.org/10.1093/petrology/33.4.891
  32. Paterson, S.R. Vernon, R.H. and Tobisch, O.T., 1989, A review of criteria for the identification of magmatic and tectonic foliations in granitoids. Jour. Structural Geol., 11, 349-363 https://doi.org/10.1016/0191-8141(89)90074-6
  33. Scoates, J.S., 2000, The plagioclase-magma density paradox re-examined and the crystallization of Proterozoic anorthosites. Jour. Petrol, 41, 627-649 https://doi.org/10.1093/petrology/41.5.627
  34. Scoates, J.S. 2002, The plagioclase-magma density paradox re-examined and the crystallization of Proterozoic anorthosites: a reply. Jour. Petrol, 43, 1979-1983 https://doi.org/10.1093/petrology/43.10.1979
  35. Taylor, Jr., H.P., 1967, The zoned ultramafic complexes of southeastern Alaska. In: Ultramafic and related rocks (ed. P.J. Wyllie), Wiley, New York, 97-121
  36. Taylor, Jr., H.P., and Noble, J.A., 1969, Origin of magnetite in the zoned ultramafic complexes of southeastern Alaska. In: Magmatic Ore Deposits (ed. H.D.B. Wilson), Economic Geol., Monographs, 4. 209-230
  37. Wager, L.R., 1963, The mechanism of adcumulus growth in the layered series of the Skaergaard intrusion. Miner. Soc. Am. Spec. Paper 1, 1-9
  38. Wager, L.R. and Brown, G.M., 1968, Layered Igneous Rocks, Oliver and Boyd, Edinburgh. 588p
  39. Wager, L.R., Brown, G.M. and Wadsworth, W.J., 1960, Types of igneous cumulates. Jour. Petrol., 1, 73-85 https://doi.org/10.1093/petrology/1.1.73
  40. Wager L.R. and Deer W.A., 1939, Geological investigations in East Greenland, Part III. The petrology of the Skaergaard Intrusion, Kangerdlugssuaq, East Greenland. Meddelelser om Gronland 105, 1-352
  41. Wilson, H.D.B., 1969, Magmatic Ore Deposits. Economic Geol., Monographs, 4. 366p