Department of Early Prehistory and Quaternary Ecology, University of Tübingen, Tübingen, Germany.
Department of Archaeology, Ethnology and Museology, Faculty of History, Archaeology and Ethnology, Al-Farabi Kazakh National University, Almaty, Kazakhstan.
PLoS One. 2022 Apr 22;17(4):e0265640. doi: 10.1371/journal.pone.0265640. eCollection 2022.
The study of lithic raw material quality has become one of the major interpretive tools to investigate the raw material selection behaviour and its influence to the knapping technology. In order to make objective assessments of raw material quality, we need to measure their mechanical properties (e.g., fracture resistance, hardness, modulus of elasticity). However, such comprehensive investigations are lacking for the Palaeolithic of Kazakhstan. In this work, we investigate geological and archaeological lithic raw material samples of chert, porphyry, and shale collected from the Inner Asian Mountain Corridor (henceforth IAMC). Selected samples of aforementioned rocks were tested by means of Vickers and Knoop indentation methods to determine the main aspect of their mechanical properties: their indentation fracture resistance (a value closely related to fracture toughness). These tests were complemented by traditional petrographic studies to characterise the mineralogical composition and evaluate the level of impurities that could have potentially affected the mechanical properties. The results show that materials, such as porphyry possess fracture toughness values that can be compared to those of chert. Previously, porphyry was thought to be of lower quality due to the anisotropic composition and coarse feldspar and quartz phenocrysts embedded in a silica rich matrix. However, our analysis suggests that different raw materials are not different in terms of indentation fracture resistance. This work also offers first insight into the quality of archaeological porphyry that was utilised as a primary raw material at various Upper Palaeolithic sites in the Inner Asian Mountain Corridor from 47-21 ka cal BP.
研究石器原料质量已成为探讨原料选择行为及其对石器技术影响的主要解释工具之一。为了对原料质量进行客观评估，我们需要测量它们的机械性能（例如，抗断裂性、硬度、弹性模量）。然而，对于哈萨克斯坦的旧石器时代，这种全面的研究还很缺乏。在这项工作中，我们研究了从内亚山地走廊（简称 IAMC）采集的燧石、斑岩和页岩的地质和考古石器原料样本。选择上述岩石的样本进行维氏和努普压痕法测试，以确定其机械性能的主要方面：它们的压痕抗断裂性（与断裂韧性密切相关的值）。这些测试辅以传统的岩矿研究，以确定矿物成分并评估可能影响机械性能的杂质水平。结果表明，斑岩等材料具有可与燧石相媲美的断裂韧性值。此前，由于斑岩的各向异性组成以及嵌入富硅基质中的粗长石和石英斑晶，人们认为其质量较低。然而，我们的分析表明，不同的原料在压痕抗断裂性方面并没有差异。这项工作还首次深入了解了在 47-21 千年前的内亚山地走廊的各个旧石器时代晚期遗址中用作主要原料的考古斑岩的质量。
