Fig. 4: Temperature-dependent metabolic transitions revealed through isotopic signatures.

a Carbon isotopes (δ13C(VPDB) Corrected) showing progressive depletion with temperature. b Sulfur isotopes (δ34S(VCDT)) displaying transition from more depleted to less depleted values at 63–64 °C. Blue dots represent measurements; light blue lines show statistically significant cubic regressions (p ≤ 0.05).