Extensive nanoindentation testing over a range of deflection depths of up to 4 μm yielded a large dataset, providing a viable framework for the statistical assessment of the mechanical properties, specifically elastic modulus () and hardness (), of compositionally diverse organic-rich mudstone samples. The data from indentations as shallow as 300–400 nm were clustered using the -means algorithm to identify three mechanical categories in the samples: a soft pseudophase (e.g., organic matter, gypsum, and clay minerals), a stiff pseudophase (e.g., quartz and feldspar), and a transitional composite-like pseudophase bridging the soft and hard minerals. The initially diverse values of and for the mechanical pseudophases were observed to converge to a constant value at indentations beyond 2–2.5 μm (varying between different samples), implying the existence of a minimal probing depth for assessing the bulk and of heterogeneous mudstone samples. The obtained bulk and values (8–21 GPa and 0.3–0.9 GPa, respectively) demonstrated a strong correlation with the mineralogical composition of the indented samples. Despite containing a notable proportion of mechanically stiff components (>45 vol%), the bulk mechanical parameters determined in this study were significantly lower than those reported for major shale formations such as the Barnett and Longmaxi Shale. This discrepancy is primarily due to the presence of organic matter with low thermal maturity (R < 0.6%), which constitutes <36 vol% of the samples, and a significant gypsum content, accounting for <15 vol%.

中文翻译：

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成分多样的世界级哈萨克斯坦烃源岩的地质力学特征和矿物学相关性：纳米压痕测试的见解


在高达 4 μm 的偏转深度范围内进行广泛的纳米压痕测试，产生了一个大型数据集，为对成分多样的富含有机物泥岩样品的机械性能（特别是弹性模量 () 和硬度 ()）进行统计评估提供了可行的框架。使用 -means 算法对浅至 300–400 nm 的压痕数据进行聚类，以识别样品中的三个机械类别：软伪相（例如有机质、石膏和粘土矿物）、刚性伪相（例如石英）和长石），以及桥接软矿物和硬矿物的过渡类复合假相。观察到机械伪相的初始不同值在超过 2-2.5 μm 的压痕处收敛到恒定值（不同样品之间有所不同），这意味着存在用于评估块体和非均质泥岩样品的最小探测深度。获得的体积和值（分别为 8-21 GPa 和 0.3-0.9 GPa）表明与压痕样品的矿物成分有很强的相关性。尽管含有显着比例的机械刚性成分 (>45 vol%)，但本研究中确定的整体机械参数明显低于 Barnett 和 Longmaxi 页岩等主要页岩地层报告的参数。这种差异主要是由于存在热成熟度较低的有机物 (R < 0.6%)，占样品的 <36 vol%，并且石膏含量很高，占 <15 vol%。