Carbonaceous shale is more topical than ever before due to the associated unconventional resources of methane. The use of FTIR, SEM-EDX, and mineralogical analyses has demonstrated a promising approach to assess methanogenesis potentials in a more rapid and reliable manner for preliminary prospecting. Representative core samples from the borehole that penetrated the carbonaceous Mikambeni shale Formations were investigated for methanogenesis potentials. The absorption band stretches from 1650 cm⁻¹ to 1220 cm⁻¹ in wavenumber, corresponding to C-O stretching and OH deformation of acetic and phenolic groups in all studied samples, thereby suggesting biogenic methanogenesis. The CO₂ was produced by decarboxylation of organic matter around 2000 cm⁻¹ and 2300 cm⁻¹ and served as a source of the carboxylic acid that dissolved the feldspar. This dissolution process tended to release K⁺ ions, which facilitated the illitization of the smectite minerals. The SEM-EDX spectroscopy depicted a polyframboidal pyrite structure, which indicated a sulfate reduction of pyrite minerals resulting from microbial activities in an anoxic milieu and causes an increase in alkalinity medium that favors precipitation of dolomite in the presence of Ca and Mg as burial depth increases. The contact diagenesis from the proximity of Sagole geothermal spring via Tshipise fault is suggested to have enhanced the transformation of smectite to chlorite via a mixed layer corrensite in a solid-state gradual replacement reaction pathway. The presence of diagenetic chlorite mineral is characteristic of low-grade metamorphism or high diagenetic zone at a temperature around 200 °C to 230 °C and corresponds to thermal breakdown of kerogen to methane at strong absorption band around 2850 cm⁻¹ and 3000 cm⁻¹, indicating thermal methanogenesis.

中文翻译：

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产甲烷潜力：来自南非林波波省 Tuli 盆地二叠纪 Mikambeni 页岩的矿物成岩作用、SEM 和 FTIR 特征的见解

由于相关的非常规甲烷资源，碳质页岩比以往任何时候都更受关注。FTIR、SEM-EDX 和矿物学分析的使用已经证明了一种有前景的方法，可以以更快速、更可靠的方式评估产甲烷潜力以进行初步勘探。研究了来自钻入碳质 Mikambeni 页岩地层的钻孔的代表性岩心样品的产甲烷潜力。吸收带的波数从 1650 cm ^-1延伸到 1220 cm ^-1，对应于所有研究样品中的 CO 拉伸和乙酸基和酚基的 OH 变形，从而表明生物产甲烷作用。CO ₂是由大约 2000 cm ^-1的有机物脱羧产生的和 2300 cm ^-1并作为溶解长石的羧酸的来源。这种溶解过程倾向于释放 K ⁺离子，促进了蒙脱石矿物的伊利石化。SEM-EDX 光谱描绘了一种多棱形黄铁矿结构，这表明缺氧环境中微生物活动导致黄铁矿矿物的硫酸盐还原，并导致碱度介质增加，这有利于在 Ca 和 Mg 存在下随着埋藏深度的增加白云石的沉淀. Sagole地热泉附近经Tshipise断层的接触成岩作用促进了蒙脱石通过固态逐渐置换反应途径中的混合层corrensite向绿泥石的转化。^-1和 3000 cm ^-1，表明热产甲烷。