The effect of iron content on the kinetics of talc dehydration and its geological significance
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摘要:
在常压下研究了2种不同铁含量滑石的原位X射线衍射高温脱水反应。选取粒径2~5μm的2种不同铁含量的滑石样品，在常压、空气氛围下进行了同步辐射原位X射线衍射脱水实验。实验结果表明，铁含量高的滑石脱水温度明显偏低，2个滑石样品在常压下发生明显脱水反应的温度相差达127℃以上。滑石在常压下的脱水动力机制为随机成核和生长机制，符合Avrami方程。将实验数据拟合Avrami方程得出：n=1.669。由实验结果可以推测，不同铁含量的滑石脱水深度可能有几十到上百千米的差别，研究铁含量与滑石脱水动力的相关性对于了解俯冲带浅-中源地震的成因机制具有重要意义。
Abstract:The effect of iron content on the kinetics of talc dehydration was studied with talc of different iron values using in-situ synchrotron X-ray diffraction (XRD).The sample particle size is 2~5μm.The air atmosphere synchrotron radiation in situ XRD de-hydration experiment was carried out under atmospheric pressure.High content of iron obviously resulted in lower dehydration tem-perature.The difference of the dehydration temperature of two samples was above 127℃.The dehydration of talc followed random nucleation and growth mechanism, and fitted Avrami equation, with n being 1.669.The results suggest that the dehydration of differ-ent iron values of talc may occur at the different depths around hundreds of kilometers, so the study was significant to the understand-ing of the genetic mechanism of earthquakes in the subduction zone.
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Keywords:
- talc /
- dehydration /
- iron content /
- in-situ /
- XRD /
- earthquake
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致谢: 感谢中国科学院上海应用物理研究所文闻老师在X射线衍射实验过程中给予的巨大帮助。
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图 2 1号滑石脱水反应XRD图谱（915℃恒温）
Tlc—滑石；En—顽火辉石；Qt—石英
Figure 2. The XRD spectrum of No 1 talc dehydration
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图 3 2号滑石脱水反应XRD图谱（700~910℃）
Tlc—滑石；En—顽火辉石；Qt—石英
Figure 3. The XRD spectrum of No.2 talc dehydration
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图 4 1号、2号滑石最强衍射峰强度在脱水反应期间的变化（2θ=4.16686°）
Figure 4. The change of the strongest diffraction peaks of No.1 and No.2 talc dehydration
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图 5 1号滑石脱水反应中滑石和顽火辉石的XRD图谱（915℃恒温）
Tlc—滑石；En—顽火辉石
Figure 5. The XRD spectra of talc and enstatite in No.1 talc dehydration
表 1 滑石的组成成分
Table 1 The composition of two kinds of talc
% 编号 SiO2 TiO2 FeO MgO CaO2 K2O Na2O Al2O3 Cr2O3 P2O5 LOI 总计 1 62.35 0.01 0.50 31.31 0.08 0.05 0.01 0.10 0.08 0.04 5.74 100.20 2 63.269 0.012 2.532 29.650 0.023 0.039 0.069 0.055 0.050 95.714 注：1号滑石为X射线荧光分析结果；2号滑石为电子探针分析结果 
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