oa FT-ICR MS Fingerprints Of Polar NSO Compounds in Sedimentary Pyrolysates Across Geological Time

This study investigates molecular fingerprints of kerogen-derived organic matter across geological time using negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI(–) FT-ICR MS). Ten sedimentary rock samples, spanning from the Ediacaran to the Upper Cretaceous and encompassing diverse depositional settings, were analyzed after open-system pyrolysis (oPy). The oPy setup, developed in-house and adapted for low-TOC samples, enables access to thermally labile polar compounds not extractable by conventional methods. Molecular formulae were assigned and grouped by elemental class and double bond equivalent (DBE). Preliminary results show that heteroatom content and aromaticity vary with inferred redox conditions. Marine anoxic samples such as Posidonia and Eagle Ford display elevated CHNO and CHNSO content with moderate to high DBE, while samples from restricted or transitional settings show more variable signatures. The Hangenberg Shale, deposited after a mass extinction, exhibits low functionalization and CHO-dominated profiles. Observed trends highlight the influence of depositional environment and biological input on molecular preservation. Ongoing work includes expanding the sample set and integrating positive-ion mode and APPI analyses to strengthen interpretations of paleoenvironmental conditions and ecological change.