Fig. 4

Petrographic images of samples from polarizan mikroskop. (1) The aggregates of the sample containing approximately 25–30% lime lumps are mainly volcanic rock fragments, with occasional metasandstone fragments and quartz minerals. The aggregates are mostly subrounded to rounded in shape. (2) The aggregates of the sample containing approximately 10–15% lime lumps are minerals (mostly quartz, occasionally alkali feldspar), and there are also rock fragments in the sample (mostly volcanic rock fragments, chloritized rock fragments, sporadic metasandstone and limestone fragments). The aggregates are generally equidimensional and slightly rounded in shape. (3) The aggregates of the sample containing sporadic brick fragments and approximately 40–45% lime lumps are mostly rock fragments (mainly volcanic rock fragments, occasional metasandstone fragments), with occasional minerals such as quartz and amphibole. The aggregates are subrounded to rounded in shape. (4) The aggregates of the sample containing approximately 40–45% lime lumps and spatially 3–5% black slag fragments and brownish masses are quartz and rock fragments. The aggregates are subrounded in shape. (5) The aggregates of the sample containing very few black slag fragments and lime lumps are predominantly sand aggregates (mineral and rock fragments) and brick fragments, almost equally distributed. The rock fragments are of volcanic type, and the minerals are quartz and amphibole. (6) The aggregates of the sample containing approximately 2–3% black slag fragments, approximately 45–50% lime lumps, and around 5% brick fragments are rock fragments (chloritized rock fragments). Additionally, there are sporadic occurrences of quartz and amphibole. The aggregates are rounded in shape. (7) The aggregates of the sample containing approximately 2–3% black slag fragments, a single piece of approximately 5–10% brick fragments, and approximately 20% lime lumps are rock fragments (volcanic type) and quartz mineral. The aggregates are subrounded to rounded in shape. (8) The sample contains approximately 30–35% lime lumps and around 10% quartz, with the remaining being volcanic rock fragments. The aggregates have angular to subangular and slightly rounded forms. (9) The aggregates of the sample containing approximately 3–5% black slag fragments and approximately 40–45% lime lumps are quartz and volcanic rock fragments. The aggregates have angular to subangular and slightly rounded forms