Viscosity of magmatic liquids: A model
Viscosity of magmatic liquids: A model
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DOI：
10.1016/j.epsl.2008.03.038
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发表时间：
2008-07-15
影响因子：
5.3
通讯作者：
Dingwell, Donald B.
中科院分区：
文献类型：
--
作者：
Giordano, Daniele;Russell, James K.;Dingwell, Donald B.
硅酸盐熔体的粘度控制着天然岩浆中岩浆的运移动力学、喷发方式和物理化学过程(如脱气、结晶)的速率。因此，岩浆液体的综合粘度模型一直是地球科学家的目标。在这里，我们提出了一个模型，它预测了硅酸盐熔体的非Arrhenian牛顿粘度作为T和熔体组成的函数，包括流变学上重要的挥发性组分H2O和F。我们的模型基于>；1770对多组分无水和富挥发分硅酸盐熔体的粘度测量。粘度的非Arrhenian T依赖关系可用VFT方程[logETA=A+B/(T(K)-C)]来解释。优化假设硅酸盐熔体粘度为常见的高温极限(A)，并返回该极限的值-4.55(+0.2)(例如，LOG ETA10(-4.6)PaS)。所有成分相关性都归因于参数B和C，并由另外17个模型系数解释。我们的模型在组成和温度空间上是连续的，并预测了15个对数单位粘度(10(-1)-10(14)PaS)以上的天然含挥发性硅酸盐熔体(SiO_2、Al_2O_3、TiO_2、FeOtot、CaO、MgO、MnO、Na_2O、K_2O、P_2O_5、H_2O、f_2O-1)的粘度。粘度模型还可以预测其他传输性质，包括玻璃化转变温度(T-g)和熔体脆性(M)。随着挥发分含量的增加，T-g和m呈现出较强的系统性下降。这种模式对预测火山喷发类型和了解硅酸盐熔体结构具有重要意义。我们的模型将长达25年的熔体粘度实验研究转变为具有预测能力的参数化，使其与包括火山学、地球物理、岩石学和材料科学在内的不同研究领域相关。(C)2008爱思唯尔B.V.保留所有权利。
The viscosity of silicate melts controls magma transport dynamics, eruption style and rates of physicochemical processes (e.g., degassing, crystallization) in natural magmas. Thus a comprehensive viscosity model for magmatic liquids has long been a goal of earth scientists. Here we present a model that predicts the non-Arrhenian Newtonian viscosity of silicate melts as a function of T and melt composition, including the rheologically important volatile constituents H2O and F. Our model is based on > 1770 measurements of viscosity on multicomponent anhydrous and volatile-rich silicate melts. The non-Arrhenian T-dependence of viscosity is accounted for by the VFT equation [log eta=A + B/(T(K) - C)]. The optimization assumes a common, high-T limit (A) for silicate melt viscosity and returns a value for this limit of -4.55 (+0.2) (e.g., log eta 10(-4.6) Pa s). All compositional dependence is ascribed to the parameters B and C and is accounted for by an additional 17 model coefficients. Our model is continuous in composition- and temperature-space and predicts the viscosity of natural volatile-bearing silicate melts (SiO2, Al2O3, TiO2, FeOtot, CaO, MgO, MnO, Na2O, K2O, P2O5, H2O, F2O-1) over fifteen log units of viscosity (10(-1)-10(14) Pa s). The model for viscosity can also predict other transport properties including glass transition temperatures (T-g) and melt fragility (m). We show strong systematic decreases in T-g and m with increasing volatile content. This pattern has implications for predicting styles of volcanic eruption and understanding silicate melt structure. Our Model transforms a quarter-century of experimental study of melt viscosities, into a parameterisation having a predictive capacity that makes it relevant to diverse fields of research including: volcanology, geophysics, petrology and material sciences. (C) 2008 Elsevier B.V. All rights reserved.