The Journal of the Petrological Society of Korea (암석학회지)

The Petrological Society of Korea (한국암석학회)
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Interpretations of Staurolite Porphyroblast and Pseudomorph Formed During Polymetamorphism Using THERMOCALC

THERMOCALC를 이용한 다변성작용 동안 성장한 십자석 반상변정과 가상의 해석

  • Kim Hyeong-Soo (Department of Earth Science Education, Kyungpook National University)
  • 김형수 (경북대학교 사범대학 지구과학교육과)
  • Published : 2006.03.01
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Abstract

Staurolite grains in staurolite, kyanite and sillimanite zones occurred in the Littleton Formation, Northcentral Massachusetts have interpreted to form by Barrovian-type metamorphism during Acadian orogeny. However, various occurrence of staurolite in the three zones, (a) porphyroblast, (b) randomly oriented and coarse-grained muscovite pseudomorph after staurolite, (c) recrystallized staurolite at the margin of garnet porphyroblast and within the pseudomorph, indicates that they have resulted from polymetamorphism. Staurolite in these three metamorphic zones can be formed by demise of chlorite or chloritoid that depends on difference of bulk-rock compositions and changes of P-T conditions. Staurolite modal proportion calculated in MnNCKFHASH system using THERMOCALC program reveals that staurolite could have grown with garnet with increasing pressure and temperature, if it coexist with chlorite. After demise of chlorite and appearance of biotite, staurolite mode decrease with increasing pressure and temperature. Therefore, based on the previous P-T paths for the Acadian metamorhism, staurolite porphyroblast grew with garnet during 400-370 Ma. Randomly oriented and coarse-grained muscovite pseudomorphs after staurolite probably have grown due to heating with appearance of kyanite and sillimanite. Consequently, pseudomorphisrn of staurolite occurred by heating derived from locally intense Alleghanian shearing (ca. 320-300 Ma) overprinted the Acadian metamorphism. Recrystallized fine-grained staurolite in sillimanite zone observed between the grain boundaries of muscovite in the pseudomorphs and at the edge of garnet porphyrobasts has formed during decreasing temperature and pressure (ca. 300-280 Ma) after peak temperature (ca. $700^{\circ}C$) of the Allegllanian metamorphism.

북중부 메사추세츠 주에 위치하는 리틀톤 층에 분포하는 십자석대, 남정석대, 규선석대에서 산출되는 십자석은 아카디안 조산운동의 바로비안(Barrovian) 형태의 변성작용에 의해 생성된 것으로 알려져 있다. 그러나 세 변성대에서 십자석은 (1) 반상변정, (2) 조립질 백운모로 치환된 가상, (3) 가상 내부와 석류석 결정 외각부에서 재결정된 십자석 등으로 다양한 형태로 산출되기 때문에, 이들은 다변성작용에 의해 형성된 것임을 지시하고, 또한 십자석의 형성은 전암성분의 차이와 온도-압력 조건의 변화에 따라 녹니석 또는 경녹니석의 소멸에 의해 형성될 수 있다. THERMOCALC 프로그램을 이용하여 MnNCKFMASH 계에서 계산된 십자석 modal proportion은 십자석이 녹니석과 공존한다면, 온도-압력이 증가하면서 석류석과 같이 성장할 수 있다 그러나 녹니석이 소멸된 후, 흑운모와 공존하면, 십자석의 modal proportion은 온도-압력이 증가하면 감소한다. 따라서 기존의 아카디안 변성작용의 온도-압력시간 경로에 의하면. 십자석 반상변정은 석류석과 같이 약 400-370Ma 시기에 형성된 것으로 판단된다. 방향성이 없고 조립질 백운모에 의해 부분적으로 또는 완전히 치환된 십자석 가상은 온도의 상승에 의해 (즉, 남정석 또는 규선석의 형성) 형성될 수 있다. 따라서 연구지역의 십자석 가상화작용은 아카디안 변성작용을 중첩한 알레게니안 전단운동(약 320-300 Ma)에 의해 국부적으로 발생한 온도의 상승으로 인해 발생한 것으로 판단된다 규선석대에서만 관찰된 석류석 결정 외각부에서 재결정된 십자석과 십자석을 치환한 조립질 백운모 견정 사이에 재결정된 십자석은 알레게니안 최고 온도 조건(약 $700^{\circ}C$)후 온도-압력이 감소하는 동안(약 300-280 Ma)재결정된 것으로 판단된다.

Keywords

References

  1. 김형수, 2000, 뉴잉글랜드 펠람돔 주변부 데본기 변성 이질암의 변성 온도-압력 경로. 한국암석학회지, 9, 211- 237
  2. Bell T.H. and Kim, H.S., 2004, Preservation of deformation and metamorphism through extensive younger orogenic overprinting: Alleghanian versus Acadian orogenesis in central New England. Jour. Struct. Geol., 26, 1591-1613 https://doi.org/10.1016/j.jsg.2004.01.006
  3. Brodie, K.H. and Rutter, E.H., 1985, On the relationship between deformation and metamorphism with special reference to the behaviour of basic rocks. In: Metamorphic Reactions, Kinetics, Textures and Deformations (eds Thompson, A.B., and Rubie, D.C.). Advanced in Physical Geochemistry, 4, 138-179
  4. Forster, C.T. Jr., 1983, Thermodynamic models of biotite pseudomorphs after staurolite. Am. Minerl., 68, 389-397
  5. Fyfe, W.S., Price, N.J. and Thompson, A.B., 1978, Fluids in the Earth's crust. Elsvier, Amsterdam
  6. Guidotti, C.V., 1970, The mineralogy and petrology of the transition from the lower to upper sillimanite zone in the Oquossoc area, Maine. Jour. Petrol., 11, 277-336 https://doi.org/10.1093/petrology/11.2.277
  7. Guidotti, C.V., Cheney, J.T. and Hernry, D.J., 1988, Compositional variation of biotite as a function of metamorphic reactions and mineral assemblage in the pelitic schists of western Maine. Am. Jour. Sci., 288A, 270-292
  8. Guidotti, C.V. and Johnson, S.E., 2002, Pseudomorphs and associated microtextures of western Maine, USA. Jour. Struct. Geol., 24, 1139-1156 https://doi.org/10.1016/S0191-8141(01)00097-9
  9. Guitotti, C.V., 1993, Textural aspects of high T-low P polymetamorphism in the Rangeley area, western Maine: general implications for studies of Acadian metamorphic rocks in New England (abstarct). Geol. Soc. Am. Abstract with Program, 25, A21
  10. Harrison, T.M., Spear, F.S. and Heizler, M.T., 1989, Geochronologic studies in central New England II: Post-Acadian hinged and differentiated uplift. Geology, 17, 185- 189 https://doi.org/10.1130/0091-7613(1989)017<0185:GSICNE>2.3.CO;2
  11. Hollocher, K.T., 1987, Systematic retrograde metamorphism of sillimanite-staurolite schist, New Salem area, Massachusetts. Geol. Soc. Am. Bull., 98, 621-634 https://doi.org/10.1130/0016-7606(1987)98<621:SRMOSS>2.0.CO;2
  12. Johnson, S.E. and Vernon, R.H., 1995, Stepping stones and pitfalls in deformation of anticlockwise P-T-t path: the low-P, high-T Cooma Complex, Australia. Jour. Metam. Geol., 13, 165-183 https://doi.org/10.1111/j.1525-1314.1995.tb00212.x
  13. Kim, H.S., 2001, A new approach to distinguishing multiple phases of metamorphism and deformation: Application to the Northeastern Appalachian. Geosciences Journal, 5, 65-84 https://doi.org/10.1007/BF02910174
  14. Kim H.S. and Bell T.H., 2005, Combining compositional zoning and foliation intersection axes (FIAs) in garnet to quantitatively determine early P-T-t paths in multiply deformed and metamorphosed schist: north central Massachusetts, USA. Contrib. Mineral. Petrol., 149, 141-163 https://doi.org/10.1007/s00410-004-0640-9
  15. Kretz, R., 1983, Symbols for rock-forming minerals. Am. Mineral., 68, 277-279
  16. Mahar E.M., Baker J.M., Powell R., Holland, T.J.B. and Howell, N., 1997, The effect of Mn on mineral stability in metapelites. Jour. Metam. Geol., 15, 223-238 https://doi.org/10.1111/j.1525-1314.1997.00011.x
  17. Moecher, D.P., 1999, The distribution, style and intensity of Alleghanian metamorphism in south-central New England: Petrologic evidence from the Pelham and Willimantic Domes. Jour. Geol., 107, 449-471 https://doi.org/10.1086/314359
  18. Powell, R. and Holland, T.J.B., 1988, An internally consistent dataset with uncertainties and correlation; 3, Applications to geobarometry, worked examples and a computer program. Jour. Metam. Geol., 6, 173-204 https://doi.org/10.1111/j.1525-1314.1988.tb00415.x
  19. Powell, R., Holland, T.J.B. and Worley, B., 1998, Calculating phase diagrams involving solid solutions via non-linear equations, with examples using THERMOCALC. Jour. Metam. Geol., 16, 577-58 https://doi.org/10.1111/j.1525-1314.1998.00157.x
  20. Reed, R.M. and Williams, M.L., 1989, Petrofabric kinematic indicators in the northern portion of the Pelham domes, north-central Massachusetts (abstract). Geol. Soc. Am. Abstract with Programs, 21, 60
  21. Robinson, P. and Tucker, R.D., 1996, The Acadian in central New England: New problems based on U-Pb ages of igneous zircon and metamorphic monazite and sphene (abstarct). Geol. Soc. Am. Abstract with Program, 28, 94
  22. Robinson, P., 1967, Gneiss domes and recumbent folds of the Orange area, west central Massachusetts. Guidebook New England Intercollegiate Geological Conference, Amherst, Massachusetts, 17-47
  23. Robinson, P., Tucker, R.D., Gromet, L.P., Ashenden, D.D., Williams, M.L., Reed, R.M. and Peterson, V.L., 1992, The Pelham Dome, Central Massachusetts: stratigraphy, geochronology, structure and metamorphism. In: P. Robinson and J.B. Brady (Eds), Guidebook for Field Trips in the Connecticut Valley Region of Massachusetts and Adjacent States, New England Intercollegiate Geological Conference, Amherst, Massachusetts 1, 132-169
  24. Spaer, F.S., 1993, Metamorphic phase equilibria and pressure- temperature-time path. Mineralogical Society of America, Monograph Series, Wasgington D.C., 799 p
  25. Spear, F.S. and Harrison, T.M., 1989, Geochronologic studies in central New England I: Evidence for pre-Acadian metamorphism in eastern Vermont. Geology, 17, 181-184 https://doi.org/10.1130/0091-7613(1989)017<0181:GSICNE>2.3.CO;2
  26. Tinkham, D.K., Zuluaga, C.A. and Stowell, H.H., 2001, Metapelite phase equilibria modeling in MnNCKFMASH: The effect of variable $Al_{2}O_{3}$ and MgO/(MgO+FeO) on mineral stability. Geol. Material. Res., 3, 1-42
  27. Tracy, R.J., Robinson, P. and Thompson, A.B. 1976, Garnet composition and zoning in the determination of temperature and pressure of metamorphism. Am. Mineral., 61, 762-775
  28. Tucker, R.D. and Robinson, P., 1990, Age and setting of the Bronson Hill magmatic arc: A re-evaluation based on UPb zircon ages in southern New England. Geol. Soc. Am. Bull. 102, 1404-1419 https://doi.org/10.1130/0016-7606(1990)102<1404:AASOTB>2.3.CO;2
  29. Tucker, R.D., Robinson, P. and Hollocher, K.T., 1990, U-Pb zircon, titanite, and monazite dating in basement rocks of the Bronsonhill anticlinorium, central Massachusetts, Geol. Soc. Am. Abstract with Program, 20, A216
  30. Vernon, R.H., 1982, Isobaric cooling of two regional metamorphic complexes related to igneous intrusions in southeastern Australia. Geology, 10, 76-81 https://doi.org/10.1130/0091-7613(1982)10<76:ICOTRM>2.0.CO;2
  31. Zartman, R.E., 1988, Three decades of geological studies in the New England Appalachians. Geol. Soc. Am. Bull., 100, 1168-1180 https://doi.org/10.1130/0016-7606(1988)100<1168:TDOGSI>2.3.CO;2
  32. Zen, E-an., Goldsmith, R., Ratcliffe, N.L., Robinson, P. and Stanley, R.S. 1983, Bedrock geological map of Massachusetts. U.S. Geological Survey, Washington D.C., scale 1:250,000