Dehydration kinetics of antigorite using in situ high-temperature infrared microspectroscopy
Dehydration kinetics of antigorite using in situ high-temperature infrared microspectroscopy
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DOI：
10.1007/s00269-013-0573-9
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发表时间：
2013-02
影响因子：
1.4
通讯作者：
M. Sawai;I. Katayama;Arisa Hamada;M. Maeda;S. Nakashima
中科院分区：
文献类型：
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作者：
M. Sawai;I. Katayama;Arisa Hamada;M. Maeda;S. Nakashima
用原位高温红外光谱研究了蛇纹石的脱水动力学。在室温下分析的反辉石样品在3,655-3,660 cm−1(带1)、3,570-3,595 cm−1(带2)和3,450-3,510 cm−1(带3)显示出相对尖锐的条带。带1对应于Mg-OH键，带2和带3对应于与Al取代Si相关的OH。在625-700℃温度范围内的等温动力学加热实验表明，随着加热时间的延长，OH带的吸光度有系统的下降。实验结果表明，一维扩散与实验数据吻合最好，其水带总面积为219kJ·−-1，水带1为245kJ±946kJ·−-1，带2为243kJ·mol-−1，带3为256s±0.53kJ·−-1。结果表明，蛇纹石的脱水过程受一维扩散控制。根据动力学数据计算了反辉石脱水过程中的产液率，范围从3×10−4到3×10−5。由于岩石的松弛速率远低于这些值，因此该速率足以引发水力破裂。这些结果表明，反辉石的快速脱水可以触发与俯冲板块有关的中等深度地震。
The dehydration kinetics of serpentine was investigated using in situ high-temperature infrared microspectroscopy. The analyzed antigorite samples at room temperature show relatively sharp bands at around 3,655–3,660 cm−1(band 1), 3,570–3,595 cm−1(band 2), and 3,450–3,510 cm−1(band 3). Band 1 corresponds to the Mg–OH bond, and bands 2 and 3 correspond to OH associated with the substitution of Al for Si. Isothermal kinetic heating experiments at temperatures ranging from 625 to 700 °C showed a systematic decrease of the OH band absorbance with heating duration. The one-dimensional diffusion was found to provide the best fit to the experimental data, and diffusion coefficients were determined with activation energies of 219 ± 37 kJ mol−1for the total water band area, 245 ± 46 kJ mol−1for band 1, 243 ± 57 kJ mol−1for band 2, and 256 ± 53 kJ mol−1for band 3. The results indicate that the dehydration process is controlled by one-dimensional diffusion through the tetrahedral geometry of serpentine. Fluid production rates during antigorite dehydration were calculated from kinetic data and range from 3 × 10−4to 3 × 10−5. The rates are high enough to provoke hydraulic rupture, since the relaxation rates of rocks are much lower than these values. The results suggest that the rapid dehydration of antigorite can trigger an intermediate-depth earthquake associated with a subducting slab.