Issue 74

N. Meddour et alii, Fracture and Structural Integrity, 74 (2025) 227-261; DOI: 10.3221/IGF-ESIS.74.16

Figure 5: Stone samples and extracted cylindrical specimens.

Figure 6: Thin sections for petrographic analysis.

R ESULTS AND DISCUSSION

Petrographic analysis etrographical examination revealed that the stone sample PE1-5 T1 was a white to beige sedimentary rock with a massive structure and grainstone texture, according to Dunham's classification. It is a fossiliferous limestone composed mainly of carbonate cement containing fossiliferous and detrital material (Fig. 7a, photomicrograph of thin section 01 showing plagioclase, quartz, microcline, and biotite under cross-polarized light at 6.3x magnification). The light-coloured cement is formed by microsparite calcite with an average size of 0.05 mm, occupying around 50% of the total volume of the rock (Fig. 7b, photomicrograph of thin section 01 showing fossils and quartz under cross- polarized light at 6.3x magnification). The rock is characterized by the presence of fossils of various shapes and sizes ranging from 0.05 to 0.6 mm, with tests that are generally whole to occasionally fragmented. Some fossils are recrystallized by secondary calcite. Detrital material is represented by disseminated quartz grains, angular in shape and varying in size from 0.05 to 0.5 mm (Fig. 7c, photomicrograph of thin section 01 showing muscovite under cross-polarized light at 6.3x magnification). The feldspars are represented by elongated plagioclases varying in size from 0.05 to 0.1 mm. The microcline is also distinguished by its squared-off macles. Biotite is rarely seen, in the form of lamellae averaging 0.3 mm in size. Muscovite appears as fine rods, ranging in size from 0.05 to 0.2 mm. Opaque minerals are poorly represented, showing isolated grains of automorphic form and ranging in size from 0.05 to 0.1mm. Porosity is marked by the presence of voids sometimes recrystallized by secondary calcite Tab. 3. For the sample PE 2 -6 (T2) the petrographic study summarised in Tab. 4, shows that it’s a fossiliferous limestone with a massive structure and grainstone texture (Fig. 8a, photomicrograph of thin section 04 showing fossils and quartz under cross-polarized light at 6.3x magnification). It is composed mainly of carbonate cement containing fossils, as well as P

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