Abstract Stromatolites from the Paleoproterozoic Jhamarkotra Formation of the Aravalli Supergroup, northwest India, provide critical archives for reconstructing early Earth environments and assessing potential biosignatures relevant to astrobiological exploration. This study integrates petrographic, spectroscopic, isotopic, and geochemical analyses to understand diagenesis, mineralogical stabilization, and preservation of organic components within these stromatolites. The stromatolites show alternating micritic-dolomitic laminae, with XRD patterns confirming dolomite as the dominant carbonate phase with subordinate calcite. FTIR and VNIR spectra exhibit absorption bands at 2650–2500 cm⁻¹ and 2312–2323 nm, respectively, typical of dolomite, while Raman spectra reveal organic signatures within carbonates with Raman shift at ∼1350 and 1600 cm⁻¹, suggesting remnants of carbonaceous matter. Isotopic compositions (δ¹³CVPDB: -2.8‰ to + 0.9‰; δ¹⁸OVPDB: -8‰ to -16‰) indicate limited diagenetic alteration and retention of primary marine signatures. REE patterns normalized to PAAS show slight HREE enrichment and variable Eu anomalies (Eu/Eu*)SN = 0.8–1.2, reflecting episodic hydrothermal influence. Mn/Sr ratios 10 across all samples imply preservation of original isotopic compositions despite post-depositional recrystallization. SEM-EDS analyses reveal micritic to coarser dolomite textures with sulfide inclusions, suggesting microbial sulfate reduction under mildly reducing conditions. The integration of geochemical and spectral datasets demonstrates that, although partial recrystallization occurred, pristine features, such as organo-mineral aggregates and microbial textural fabrics, remain well preserved. The spectral detectability of these organics and minerals establishes a methodological link to remote life-detection strategies. These findings underscore the utility of stromatolites as analog archives for assessing potential biosignatures on Mars, where carbonate-bearing deposits may similarly retain spectral fingerprints of microbial activity.
K et al. (Wed,) studied this question.