A model for monazite/ melt equilibrium and application to the generation of granitic magmas
A model for monazite/ melt equilibrium and application to the generation of granitic magmas
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DOI：
10.1016/0009-2541(93)90250-m
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发表时间：
1993-11
期刊：
影响因子：
3.9
通讯作者：
J. Montel
中科院分区：
文献类型：
--
作者：
J. Montel
为了模拟大陆地壳中Zr、Hf、Ti、P、U、Th、Y和稀土元素（REE）的行为，必须确定控制副矿物与花岗岩熔体之间平衡的参数。本文提出了独居石和贫钙长英质熔体之间的平衡方程。在第一步中，所有的轻稀土元素被认为是一个单一的组成部分，并从现有的实验数据推导出一个方程描述独居石的溶解度。第二步，以秘鲁Macusani的独居石和黑曜石共存的天然实例为基础，研究独居石对稀土元素的分馏作用。独居石的溶解度可以作为温度计，以天然岩浆岩的稀土总量为基准。稀土元素测温法在各种过铝质岩系中的应用表明，它是确定岩浆作用温度的可靠工具。独居石的稀土分馏方程用于讨论熔体和假定的母岩之间的成因关系，使用的独居石在母岩和子岩的稀土元素模式的组合物。该方法已成功地应用于高喜马拉雅玛纳斯鲁和西藏板状花岗岩。独居石的详细岩相学工作，包括电子探针分析和扫描电镜成像的内部结构，结合这里提出的模型，可以是一个有用的工具，破译成因和分化的过铝质花岗岩岩浆在大陆地壳。
In order to model the behaviour of Zr, Hf, Ti, P, U, Th, Y and the rare-earth elements (REE) in the continental crust, the parameters which control the equilibria between accessory minerals and granitic melts must be determined. This paper proposes equations for the equilibrium between monazite and Ca-poor felsic melts. In a first step, all the light REE are considered as a single component and an equation describing monazite solubility is deduced from the available experimental data. In a second step, the fractionation of REE by monazite is investigated on the basis of a natural example of coexisting monazite and obsidian from Macusani, Peru. The solubility of monazite can be used as a thermometer, based on the total REE content of natural magmatic rocks. Application of REE thermometry to various peraluminous rock series suggests that it is a reliable tool for determining temperatures of magmatic processes. The equation governing REE fractionation by monazite is used to discuss genetic relationships between a melt and a presumed parental rock, using the composition of the monazite in the parental rocks and the REE pattern of the daughter rock. This method has been applied successfully to High Himalayan Manaslu and Tibetan Slab granites. It is suggested that detailed petrographical work on monazite including electron microprobe analyses and SEM imaging of its internal structures, combined with the model presented here, can be a useful tool for deciphering the genesis and the differentiation of peraluminous granitic magmas in the continental crust.