Structural changes induced by thermal maturation of dispersed organic matter (OM) in the Shimanto accretionary complex, southwest Japan, were investigated using micro‐Fourier‐transform infrared spectroscopy and micro‐Raman spectroscopy. Natural dispersed OM exhibits systematic structural changes inferred from D1‐ and G‐band FWHM values, Raman band separation (RBS), and intensity ratios of the D1‐ and G‐bands (I_D1/I_G ratio) from diagenetic zone to anchizone (IC values: 0.75–0.30). Infrared spectra indicate a loss of aliphatic CH _x, aromatic CH _x, and oxygen‐containing structures as temperature increases. These changes are consistent with discontinuities in thermal structures bounded by out‐of‐sequence thrusts. Kinetic pyrolysis experiments indicate that the I_D1/I_G ratio of synthesized OM has a power law relationship with heat treatment time. Kinetic models of temperature dependence were fitted using the I_D1/I_G ratio, and an effective activation energy of 106 ±17 kJ/mol was estimated using an Arrhenius equation. The activation energies estimated by power law rate and Avrami models have a least‐square correlation coefficient of 0.93, indicating the temperature dependence of carbonization. The estimated effective activation energy is consistent with that of coal, lignin, cellulose, and hemicellulose during thermal degradation. On the other hand, RBS, and D1‐ and G‐band FWHM values of OM display more complex changes with increasing heating temperature and time, and it is difficult to constrain rate parameters during pyrolysis experiments. Our data indicate that the I_D1/I_G ratio is controlled by a simple thermally activated process, whereas RBS and D1‐ and G‐band FWHM values can be affected by lithostatic pressure, fluid activity, hydrogen index, and host lithology, as well as temperature. Structural evolution of dispersed OM in mudstones differs between natural and anhydrous closed experimental systems. Natural carbonization based on micro‐Raman spectroscopy should be applied for a limited indicator of thermal maturation, especially for dispersed OM in diagenetic zone.

中文翻译：

---

泥岩中分散有机物的自然和实验结构演化：日本西南部的四万十增生复合体

使用微傅里叶变换红外光谱法和显微拉曼光谱法研究了日本西南部Shimanto增生复合体中由分散有机质（OM）的热成熟引起的结构变化。天然分散的OM表现出从_D1带和G带的FWHM值，拉曼带分离（RBS）以及从成岩带到an裂带的_D1带和G带的强度比（I _D1 / I _G比）推断的系统结构变化（ IC值：0.75–0.30）。红外光谱表明脂肪族CH _x，芳香族CH _x的损失 ，以及随着温度升高的含氧结构。这些变化与以逆序推力为边界的热结构的不连续性是一致的。动力学热解实验表明，合成OM的I _D1 / I _G比与热处理时间呈幂律关系。使用I _D1 / I _G拟合温度依赖性的动力学模型使用Arrhenius方程估算出有效活化能为106±17kJ / mol。幂律率和Avrami模型估计的活化能的最小二乘相关系数为0.93，表明碳化的温度依赖性。在热降解过程中，估计的有效活化能与煤，木质素，纤维素和半纤维素的活化能一致。另一方面，随着加热温度和时间的增加，OM的RBS以及D1和G波段的FWHM值显示出更复杂的变化，并且在热解实验期间很难限制速率参数。我们的数据表明I _D1 / I _G比率可以通过简单的热激活过程来控制，而RBS，D1和G波段的FWHM值会受到静压压力，流体活度，氢指数，主体岩性和温度的影响。天然和无水密闭实验系统中，泥岩中分散的OM的结构演变不同。基于显微拉曼光谱的自然碳化应作为热成熟的有限指标，特别是对于成岩带中的分散OM。