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罗丁石

维基百科,自由的百科全书
罗丁岩,地点:马里兰州

罗丁岩(英语:Rodingite)是由钙铁榴石、钙辉石(calcic pyroxene)、符苏岩(vesuvianite)、绿帘石和方柱石(scapolite)组成的交代变质岩 [1]。 主要产于镁铁质岩石靠近蛇纹石化的超镁铁质岩石的地方。 当超镁铁质岩石被镁铁质岩石被蛇纹石化时,所排除的流体副产品含高 pH 值、Ca2+ 和 OH- ,与镁铁质岩石接触后,发生交代变质作用,而造罗丁岩[2][3],罗丁岩的矿物组成变化很大,但都具有高钙、和低硅的特征[4]。 罗丁岩产出最多的地方是蛇绿岩、蛇纹岩混杂岩、海底橄榄岩和榴辉岩地区中。 罗丁岩是根据在新西兰,罗丁河出露的顿山蛇绿岩带的露头而命名[5]

在蛇绿岩 (绿色)的罗丁岩岩墙(白色), 地点:Dun Mountain 蛇绿岩带, 新西兰

罗丁石化

罗丁石化的过程是渐变的。例如在蛇绿岩中的捕虏岩, 其中榴辉岩的罗丁石化 ,从体积,矿物组成,化学成分及纹理都呈现出连续变化。完全被罗丁石化的岩石,其矿物的组合与原岩差异很大[6][7]

全球元素循环

罗丁石化是全球元素循环重要作用之一。它能消除洋壳在变质时大量产出的的Ca。由于洋壳在地球表面的广泛分布,海洋岩石圈的超镁铁质岩在被石蛇纹岩化时,会释出大量Ca。 而罗丁岩的形成就能吸收这些Ca。保持Ca元素在全球的平衡。罗丁岩中的稳定Ca 和放射性 Sr 同位素的组成,与地幔特征相似,因此可证明罗丁石的 Ca 和 Sr 来自地幔 [8]

参考文献

  1. ^ Fettes, Douglas; Desmons, Jacqueline (2007). Metamorphic Rocks - A Classification and Glossary of Terms. Cambridge University Press.
  2. ^ Laborda-López, Casto; López-Sánchez-Vizcaíno, Vicente; Marchesi, Claudio; Gómez-Pugnaire, María Teresa; Garrido, Carlos J.; Jabaloy-Sánchez, Antonio; Padrón-Navarta, José A.; Hydas, Károly (2018). "High‐P metamorphism of rodingites during serpentinite dehydration (Cerro del Almirez, Southern Spain): Implications for the redox state in subduction zones". Journal of Metamorphic Geology. 36: 1141–1173. doi:10.1111/jmg.12440.
  3. ^ Salvioli-Mariani, Emma; Boschetti, Tiziano; Toscani, Lorenzo; Montanini, Alessandra; Petriglieri, Jasmine Rita; Bersani, Danilo (2020). "Multi-stage rodingitization of ophiolitic bodies from Northern Apennines (Italy): Constraints from petrography, geochemistry and thermodynamic modelling". Geoscience Frontiers. 11: 2103–2125. doi:10.1016/j.gsf.2020.04.017.
  4. ^ Python; Marie; Masako; Yoshikawa; Tomoyuki Shibata; Shoji Arai (2011). Dyke swarms: Keys for geodynamic interpretation. Berlin, Heidelberg: Springer. pp. 401–435. Bibcode:2011dskg.book.....S.
  5. ^ Johnston, M. R. (2007). "Nineteenth-century observations of the Dun Mountain Ophiolite Belt, Nelson, New Zealand and trans-Tasman correlations". Geological Society, London, Special Publications. 287 (1): 375–387. Bibcode:2007GSLSP.287..375J. doi:10.1144/sp287.27.
  6. ^ LI, X.-P., ZHANG, L., WEI, C., AI, Y. and CHEN, J. (2007), Petrology of rodingite derived from eclogite in western Tianshan, China. Journal of Metamorphic Geology, 25: 363-382. https://doi.org/10.1111/j.1525-1314.2007.00700.x
  7. ^ Barriga, F., Fyfe, W.S. Development of rodingite in basaltic rocks in serpentinites, East Liguria, Italy. Contr. Mineral. and Petrol. 84, 146–151 (1983). https://doi.org/10.1007/BF00371281
  8. ^ Nikolaus Gussone, Håkon Austrheim, Anne Westhues, Klaus Mezger(2020), Origin of Rodingite Forming Fluids Constrained by Calcium and Strontium Isotope Ratios in the Leka Ophiolite Complex, Chemical Geology, Volume 42, , 119598, ISSN 0009-2541, https://doi.org/10.1016/j.chemgeo.2020.119598. (https://www.sciencedirect.com/science/article/pii/S0009254120301376)