In this investigation, two different varieties of ‘Prada’ limestones were studied: a dark grey texture, bearing quartz, clay minerals, organic matter and pyrites, and a light grey texture with little or no presence of such components. We have observed two effects of different intensity when heating the dark texture from 400 °C: (1) the explosion of certain samples and (2) greater thermal damage than in the light grey texture. Chemical and mineralogical composition, texture, microstructure, and physical properties (i.e. colour, open porosity, P and S-wave velocity) have been evaluated at temperatures of 105, 300, 400, and 500 °C in order to identify differences between textures. The violence of the explosive events was clear and cannot be confounded with ordinary splitting and cracking on thermally treated rocks: exploded samples underwent a total loss of integrity, displacing and overturning the surrounding samples, and embedding fragments in the walls of the furnace, whose impacts were clearly heard in the laboratory. Thermogravimetric results allowed the identification of a process of oxidation of pyrites releasing SO2 from 400 °C. This process jointly with the presence of microfissures in the dark texture, would cause a dramatic increase in pore pressure, leading to a rapid growth and coalescence of microcracks that leads to a process of catastrophic decay in rock integrity. In addition to the explosive events, average ultrasound velocities and open porosity showed a greater variation in the dark grey texture from 400 °C. That result also points towards a significant contribution of oxidation of pyrites on the thermo-chemical damage of the rock, among other factors such as the pre-existence of microfissures and the thermal expansion coefficient mismatch between minerals. Implications in underground infrastructure and mining engineering works are critical, as the explosive potential of pyrite-bearing limestones bears risk for mass fracturing and dramatic strength decay from 400 °C. Moreover, SO2 released has harmful effects on health of people and the potential to form acid compounds that corrode materials, shortening their durability and increasing maintenance costs.

中文翻译：

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含黄铁矿的石灰石的温度诱发爆炸行为和热化学损伤：原因和机制

在这项调查中，研究了两种不同种类的“普拉达”石灰岩：深灰色质地，含有石英、粘土矿物、有机物质和黄铁矿，以及浅灰色质地，几乎没有或没有此类成分。当从 400 °C 加热深色纹理时，我们观察到两种不同强度的影响：（1）某些样品的爆炸和（2）比浅灰色纹理更大的热损伤。已在 105、300、400 和 500 °C 的温度下对化学和矿物组成、质地、微观结构和物理特性（即颜色、开孔率、P 和 S 波速度）进行了评估，以识别质地之间的差异。爆炸事件的剧烈程度是明确的，不能与热处理岩石上的普通劈裂和开裂混淆：爆炸的样品完全丧失了完整性，周围的样品被移位并倾覆，碎片嵌入炉壁，在实验室中可以清楚地听到其撞击声。热重结果允许鉴定黄铁矿从 400 °C 释放 SO2 的氧化过程。这一过程与暗纹理中微裂缝的存在共同导致孔隙压力急剧增加，导致微裂缝的快速增长和合并，从而导致岩石完整性的灾难性衰减过程。除了爆炸事件外，平均超声速度和开放孔隙度在 400°C 后的深灰色纹理中显示出更大的变化。该结果还表明黄铁矿氧化对岩石的热化学损伤有显着贡献，除其他因素外，例如微裂缝的预先存在和矿物之间的热膨胀系数不匹配。对地下基础设施和采矿工程的影响至关重要，因为含黄铁矿的石灰岩的爆炸潜力在 400 °C 时存在大规模破裂和强度急剧下降的风险。此外，释放的二氧化硫对人体健康有害，并有可能形成腐蚀材料的酸性化合物，缩短材料的耐用性并增加维护成本。因为含黄铁矿的石灰岩具有爆炸潜力，从 400 °C 开始存在大规模破裂和强度急剧下降的风险。此外，释放的二氧化硫对人体健康有害，并有可能形成腐蚀材料的酸性化合物，缩短材料的耐用性并增加维护成本。因为含黄铁矿的石灰岩具有爆炸潜力，从 400 °C 开始存在大规模破裂和强度急剧下降的风险。此外，释放的二氧化硫对人体健康有害，并有可能形成腐蚀材料的酸性化合物，缩短材料的耐用性并增加维护成本。