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花崗變晶岩

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花崗變晶岩(英語:Granofels)是指中到粗粒變質岩,具有等顆粒,它形晶和顯晶石特徵的紋理[1]。典型變質岩例如石英岩、大理岩、紫蘇花崗岩和其他,沒有葉理和缺失斑狀變晶的變質岩,均屬花崗變晶岩。 這些變質岩通常其顆粒肉眼可見、且顆粒之間為彌合邊界,多由三鄰近顆粒相接,相交處為120° 相交[2].。 但在應力下,能產生葉理結構,導致片狀紋理[3]。但花崗變晶岩缺乏明顯的葉面理或線狀理[4].


廣為人所知的岩石,例如大理石角岩,均屬花崗變晶岩[5].

角岩是一組接觸變質岩的組名,是和火成岩接觸而造成的高溫變質岩。具堅硬、易碎,堅韌和耐用特點。這些特性是由於片狀或稜柱狀細粒晶體呈無規則排列[6] [7] [2]

角岩的原岩,有砂岩頁岩板岩石灰岩等。經過變質後。它們原有的層理或解理面會消失,當和火山活動帶來的熱液接觸時,會造成交代作用(英語:metasomatism),原岩的成分會變化[8]。角岩最常見於上地殼或中地殼的花崗岩侵入體的周邊。最常見的角岩是黑雲母角岩,呈深褐色至黑色,含大量閃亮的黑色雲母小晶體[9]

大理岩石灰岩白雲岩等受接觸、區域變質作用重結晶形成,方解石和白雲石的含量一般大於50%,有的達99%。大理岩遇稀鹽酸反應產生二氧化碳。這是因為含有石灰的岩石遇稀鹽酸會產生化學反應。這個效應時常被用來測定岩石是否含有石灰[10]。 化學反應:CaCO3+2HCl→ CaCl2+CO2+H2O

一般大理岩中含有少量的其他變質礦物,屬於碳酸鹽類石材,其主要成分以碳酸鈣為主,約佔50%以上,由於原來岩石中所含雜質不同(矽質、泥質、碳質、鐵質、火山碎屑物質等),及變質作用的溫度、壓力、水含量等差別,伴生礦物也不同[11]。如:

  • 由較純的碳酸鹽岩石形成的大理岩中,方解石、白雲石佔90%以上,有時可含很少的石墨、白雲母、磁鐵礦、黃鐵礦等,在低溫高壓下方解石可轉變成文石 [12]
  • 由含矽質的碳酸鹽岩石形成的大理岩中,在中、低溫時可含有滑石、透閃石、陽起石、石英等,在中、高溫時可含有透輝石、斜方輝石、鎂橄欖石、矽灰石、方鎂石等,在高溫低壓條件下可出現粒矽鈣石、鈣鎂橄欖石、鎂黃長石等[13]
  • 由含泥質的碳酸鹽岩石形成的大理岩中,在中、低溫時可含有蛇紋石、綠泥石、綠簾石黝簾石、符山石、黑雲母、酸性斜長石、微斜長石等,在中、高溫時可含有方柱石、鈣鋁榴石、粒矽鎂石、金雲母、尖晶石磷灰石、中基性斜長石、正長石等[14]

大理岩一般有典型的粒狀變晶結構,顆粒粗細不一。岩石中的方解石、白雲石顆粒之間成緊密鑲嵌結構。在某些區域變質作用形成的大理岩中,由於方解石的光軸成定向排列,使大理岩具有較強的透光性,有的大理岩可透光2厘米,是優良的雕刻材料。大理岩多為塊狀構造,也有不少具條帶、條紋、斑塊或斑點等構造,經過加工後成為有不同顏色和花紋的裝飾建築材料[15]

參考文獻

  1. ^ Bucher, K ., & Grapes, R. (2011). Petrogenesis of metamorphic rocks. Springer Science & Business Media
  2. ^ 2.0 2.1 Philpotts, A., & Ague, J. (2009). Principles of igneous and metamorphic petrology. Cambridge University Press
  3. ^ Howie, R. A., Zussman, J., & Deer, W. (1992). An introduction to the rock-forming minerals (p. 696). Longman
  4. ^ Goldsmith, Richard (1959). "Granofels, a New Metamorphic Rock Name". The Journal of Geology. 67 (1): 109–110. Bibcode:1959JG.....67..109G. doi:10.1086/626561.
  5. ^ Schmi, Rolf; Fettes, Douglas; Harte, Ben; Davis, Eleutheria; Desmons, Jacqueline (2007). "How to name a metamorphic rock". British Geological Survey.
  6. ^ Yardley, Bruce W.D. (1989). An introduction to metamorphic petrology. Harlow, Essex, England: Longman Scientific & Technical. pp. 12, 26. ISBN 0582300967
  7. ^ Blatt, Harvey; Tracy, Robert J. (1996). Petrology : igneous, sedimentary, and metamorphic (2nd ed.). New York: W.H. Freeman. pp. 367, 512. ISBN 0716724383.
  8. ^ Harry, W. T. (December 1952). "Basic hornfels at a gabbro contact near Carlingford, Eire". Geological Magazine. 89 (6): 411–416. Bibcode:1952GeoM...89..411H. doi:10.1017/S0016756800068114.
  9. ^ Flett, John Smith (1911). "Hornfels" . In Chisholm, Hugh (ed.). Encyclopædia Britannica. 13(11th ed.). Cambridge University Press. pp. 710–711
  10. ^ Environmental degradation of marble". What is Chemistry?. University Federico II of Naples, Italy. Retrieved 5 November 2021.
  11. ^ Shushakova, V., Fuller, E.R., Heidelbach, F. et al. Marble decay induced by thermal strains: simulations and experiments. Environ Earth Sci 69, 1281–1297 (2013). https://doi.org/10.1007/s12665-013-2406-z
  12. ^ O. Akkoyun, "An evaluation of image processing methods applied to marble quality classification," 2010 2nd International Conference on Computer Technology and Development, 2010, pp. 158-162, doi: 10.1109/ICCTD.2010.5646128.
  13. ^ J. Martinez-Alajarin, J. D. Luis-Delgado and L. M. Tomas-Balibrea, "Automatic system for quality-based classification of marble textures," in IEEE Transactions on Systems, Man, and Cybernetics, Part C (Applications and Reviews), vol. 35, no. 4, pp. 488-497, Nov. 2005, doi: 10.1109/TSMCC.2004.843236.
  14. ^ I. Ar and Y. S. Akgul, "A generic system for the classification of marble tiles using Gabor filters," 2008 23rd International Symposium on Computer and Information Sciences, 2008, pp. 1-6, doi: 10.1109/ISCIS.2008.4717915.
  15. ^ Chang, R., Wei, Y., Ma, L., Wang, Y., Liu, H., Song, M. (2011). The Judgment of Beef Marble Texture Based on the MATLAB Image Processing Technology. In: Li, D., Liu, Y., Chen, Y. (eds) Computer and Computing Technologies in Agriculture IV. CCTA 2010. IFIP Advances in Information and Communication Technology, vol 346. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-18354-6_15