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花岗变晶岩

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花岗变晶岩(英语:Granofels)是指中到粗粒变质岩,具有等颗粒,它形晶和显晶石特征的纹理[1]。典型变质岩例如石英岩、大理岩、紫苏花岗岩和其他,没有叶理和缺失斑状变晶的变质岩,均属花岗变晶岩。 这些变质岩通常其颗粒肉眼可见、且颗粒之间为弥合边界,多由三邻近颗粒相接,相交处为120° 相交[2].。 但在应力下,能产生叶理结构,导致片状纹理[3]。但花岗变晶岩缺乏明显的叶面理或线状理[4].


广为人所知的岩石,例如大理石角岩,均属花岗变晶岩[5].

角岩是一组接触变质岩的组名,是和火成岩接触而造成的高温变质岩。具坚硬、易碎,坚韧和耐用特点。这些特性是由于片状或棱柱状细粒晶体呈无规则排列[6] [7] [2]

角岩的原岩,有砂岩页岩板岩石灰岩等。经过变质后。它们原有的层理或解理面会消失,当和火山活动带来的热液接触时,会造成交代作用(英语:metasomatism),原岩的成分会变化[8]。角岩最常见于上地壳或中地壳的花岗岩侵入体的周边。最常见的角岩是黑云母角岩,呈深褐色至黑色,含大量闪亮的黑色云母小晶体[9]

大理岩石灰岩白云岩等受接触、区域变质作用重结晶形成,方解石和白云石的含量一般大于50%,有的达99%。大理岩遇稀盐酸反应产生二氧化碳。这是因为含有石灰的岩石遇稀盐酸会产生化学反应。这个效应时常被用来测定岩石是否含有石灰[10]。 化学反应:CaCO3+2HCl→ CaCl2+CO2+H2O

一般大理岩中含有少量的其他变质矿物,属于碳酸盐类石材,其主要成分以碳酸钙为主,约占50%以上,由于原来岩石中所含杂质不同(硅质、泥质、碳质、铁质、火山碎屑物质等),及变质作用的温度、压力、水含量等差别,伴生矿物也不同[11]。如:

  • 由较纯的碳酸盐岩石形成的大理岩中,方解石、白云石占90%以上,有时可含很少的石墨、白云母、磁铁矿、黄铁矿等,在低温高压下方解石可转变成文石 [12]
  • 由含硅质的碳酸盐岩石形成的大理岩中,在中、低温时可含有滑石、透闪石、阳起石、石英等,在中、高温时可含有透辉石、斜方辉石、镁橄榄石、硅灰石、方镁石等,在高温低压条件下可出现粒硅钙石、钙镁橄榄石、镁黄长石等[13]
  • 由含泥质的碳酸盐岩石形成的大理岩中,在中、低温时可含有蛇纹石、绿泥石、绿帘石黝帘石、符山石、黑云母、酸性斜长石、微斜长石等,在中、高温时可含有方柱石、钙铝榴石、粒硅镁石、金云母、尖晶石磷灰石、中基性斜长石、正长石等[14]

大理岩一般有典型的粒状变晶结构,颗粒粗细不一。岩石中的方解石、白云石颗粒之间成紧密镶嵌结构。在某些区域变质作用形成的大理岩中,由于方解石的光轴成定向排列,使大理岩具有较强的透光性,有的大理岩可透光2厘米,是优良的雕刻材料。大理岩多为块状构造,也有不少具条带、条纹、斑块或斑点等构造,经过加工后成为有不同颜色和花纹的装饰建筑材料[15]

参考文献

  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