Toward a quantitative model of metamorphic nucleation and growth
Toward a quantitative model of metamorphic nucleation and growth
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DOI：
10.1007/s00410-011-0635-2
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发表时间：
2011-11-01
影响因子：
3.5
通讯作者：
de Capitani, C.
中科院分区：
文献类型：
--
作者：
Gaidies, F.;Pattison, D. R. M.;de Capitani, C.
在多组分模型系统中，基于经典的成核和反应速率理论以及吉布斯自由能耗散，模拟了等压加热过程中变质石榴石的形成过程。研究了界面能、石榴石团簇表面化学迁移率、升温速率和压力对界面控制石榴石形核和生长动力学的相关影响。据发现，界面能控制偏离平衡所需的成核石榴石，如果在石榴石的表面的附着和分离过程限制的整体结晶速率。BC省纳尔逊陨石晕的变岩中石榴石成核的界面能估计在0.03和0.3 J/m（2）之间，压力约为1.5 J/m（2）。3,500巴这对应于Ca的石榴石形成反应的热过度。30 A摄氏度。加热速率对热超跃的影响可以忽略不计。一个显着的反馈之间的化学分馏与石榴石形成和石榴石的成核和晶体生长的动力学引起其对数正态形的晶体尺寸分布预测。
The formation of metamorphic garnet during isobaric heating is simulated on the basis of the classical nucleation and reaction rate theories and Gibbs free energy dissipation in a multi-component model system. The relative influences are studied of interfacial energy, chemical mobility at the surface of garnet clusters, heating rate and pressure on interface-controlled garnet nucleation and growth kinetics. It is found that the interfacial energy controls the departure from equilibrium required to nucleate garnet if attachment and detachment processes at the surface of garnet limit the overall crystallization rate. The interfacial energy for nucleation of garnet in a metapelite of the aureole of the Nelson Batholith, BC, is estimated to range between 0.03 and 0.3 J/m(2) at a pressure of ca. 3,500 bar. This corresponds to a thermal overstep of the garnet-forming reaction of ca. 30A degrees C. The influence of the heating rate on thermal overstepping is negligible. A significant feedback is predicted between chemical fractionation associated with garnet formation and the kinetics of nucleation and crystal growth of garnet giving rise to its lognormal-shaped crystal size distribution.