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Abstract EANA2025-21


Calcite-Mediated Preservation of Prebiotic Molecules in a High-Altitude Hydrothermal System: Insights from Puga Hot Spring, Ladakh, India

Amritpal Singh Chaddha(1,2*), Sunil Kumar Shukla(2), Anupam Sharma(1,2), Kamlesh Kumar(1,2), M.G. Thakkar(2), Devendra Kumar Patel(3), G.N.V. Satyanarayana(3)
(1)Geochemistry Laboratory, Birbal Sahni Institute of Palaeosciences, Lucknow -226 007, India. (2) Earth and Planetary Exploration Group (EPEG), Birbal Sahni Institute of Palaeosciences, Lucknow - 226 007, India. (3)Analytical Chemistry, Regulatory Toxicology Group, CSIR-Indian Institute of Toxicology Research; Lucknow – 226 001, India.


Understanding how mineral surfaces concentrate, catalyse, and preserve prebiotic molecules is crucial for decoding life’s origins. Laboratory experiments have shown that calcium carbonate can facilitate peptide bond formation and nucleoside phosphorylation, yet in situ evidence from natural settings remains limited. This study evaluates whether travertine deposits at the Puga hot spring (4,414 m a.s.l., Ladakh, India) serve as both reactors and archives for early organic chemistry under cold, CO₂-rich hydrothermal conditions.

We analysed a white travertine from the Puga hot spring and applied an interdisciplinary suite of techniques for biogeochemical fingerprinting such as mineralogical textures, major, trace, REEs concentration, and preserved organic signatures. The deposit proved to be >99 wt % low-Mg calcite with foliated and rhombohedral morphologies entrapping diatoms, while GC-MS/MS revealed β-alanine, formamide, pyran-2-thione, cyclooctasulphur, and hexadecenoic methyl ester co-localized with carbonate phases; major-element data (CaO > 93 wt %) showed enrichments in Sr, Cs, and Ba and depletions in HFSEs/REEs, and isotopic values (δ 13 C ≈ –5 ‰, δ18O ≈ –24 ‰ VPDB) support a model of rapid CO2 degassing and cooling in a meteoric-influenced, cold-climate hydrothermal system.

Puga travertine functions as a dual catalyst–matrix system, encapsulating and protecting prebiotic molecules and microbial remnants during rapid carbonate precipitation. We propose a four-stage model- (1) CO2-driven nucleation, (2) organic adsorption and catalysis, (3) diatom entombment, and (4) progressive burial that underscores the potential of calcite sinters as natural analogues for early-Earth and extraterrestrial life-detection environments. This work is a classic example of research attempting from field to the lab and into the space which bridges laboratory findings with field evidence, advancing our understanding of mineral-templated prebiotic chemistry.