Estimation of oxygen diffusivity from anion porosity in minerals
Estimation of oxygen diffusivity from anion porosity in minerals
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DOI：
10.2343/geochemj.32.71
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发表时间：
1998-04
影响因子：
0.8
通讯作者：
Yong‐Fei Zheng;B. Fu
中科院分区：
文献类型：
--
作者：
Yong‐Fei Zheng;B. Fu
提出了一种利用阴离子孔隙度预测多种矿物氧扩散率的经验模型。它是基于在无水和热液条件下的实验扩散数据的检查。假设所有矿物的活化能与指前因子之间的关系遵循一个共同的补偿规律，无论扩散介质是H2O、OH-、CO2还是O2。然而，H2O分子和OH-基团体积相对较小，因此在具有给定阴离子孔隙度的矿物结构中比CO2和O2更容易迁移。因此，热液条件下氧在矿物中的扩散速率大于无水条件下。在无水和热液条件下，分别估计了约130种矿物中氧扩散的Arrhenius参数。对于具有地球化学意义的矿物，氧扩散率的经验结果是内部一致的，因此可以应用于高温矿物组合冷却过程中的氧同位素地质速度测定。
An empirical model for predicting oxygen diffusivity from anion porosity is presented for a wide range of minerals. It is based on the examination of experimental diffusion data under anhydrous and hydrothermal conditions. The relationship between activation energies and pre-exponential factors in all minerals is assumed to obey a common compensation law regardless of diffusion medium (H2O, OH-, CO2 or O2). However, the H2O molecules and OH- groups are relatively small in volume and thus can migrate within mineral structures with given anion porosities easier than the CO2 and O2. As a result, the rates of oxygen diffusion in minerals under hydrothermal conditions are greater than those under anhydrous conditions. The Arrhenius parameters for oxygen diffusion in about 130 minerals have been estimated for the anhydrous and hydrothermal conditions, respectively. The empirical results on oxygen diffusivity are internally consistent for the minerals of geochemical interest and thus can be applicable to oxygen isotope geospeedometry during cooling of high-temperature mineral assemblages.