oa Characterization of Sulfur-Bound Lipids in a Transiently Euxinic Lagoon

The biogeochemical investigation of modern analogues for ancient euxinic environments is fundamental to our understanding of the deposition and preservation of biolipids under sulfidic conditions. Thus, contemporary meromictic lakes and stratified marine basins, where sulfide accumulates beneath oxygenated surface waters, serve as reference points for our understanding of organic matter preservation during past periods of oceanic euxinia. Lipid sulfurization appears to take place very rapidly thus rendering a significant lipid component undetectable using conventional GC-MS and LC-MS methods. Through the conversion of biolipids to their fossil lipid counterparts via catalytic hydrogenation of the unsaturated lipids we uncovered the partially reduced GSB carotenoids chlorobactane, paleorenieratane, and isorenieratane. The GSB carotenoids chlorobactane, -isorenieratane, and isorenieratane released from the sulfur-bound fraction via Raney Ni desulfurization is a testament to the rapid sulfurization in euxinic water column. The presence of GSB carotenoids during an ephemeral episode of euxinia in an otherwise shallow water column that is contact with the atmosphere complicates the use of chlorobactane and isorenieratane in the rock record as proxies for oceanic anoxic events.