Isoprenoidal GDGTs and GDDs associated with anoxic lacustrine environments

We examined membrane-spanning archaeal lipids using ultra high pressure liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) in a suite of sediment samples from both cored sequences (Messel oil shale and Lake Chala) surface sediments (Azorean lakes) encompassing ancient modern (Eocene to Present) lacustrine environments. Additionally we compared the data those marine (Mediterranean sequences, Arabian Sea Monterey outcrop sediments) hypersaline (Vena del Gesso marls) as well suspended particulate matter (SPM) Black Sea. Regular isoprenoidal glycerol dialkyl tetraethers (GDGTs) diethers (GDDs) were most abundant all investigated settings (>90 % 84 respectively). Interestingly, GDGTs with cyclohexyl ring (S-GDGTs) also present almost lake sediments, relative abundances ca. 2–7 and, for first time, their S-GDD counterparts detected (2–10 %). The producers S-GDGTs are still unknown, however our results show that it is likely bottom water anoxia (both seasonally induced or permanent) driving factor production these lipids, whereas previous studies suggested euxinia was required production. Unsaturated (uns-GDGTs, 2 %) only Chala Azorean lakes, but without accompanying uns-GDDs. GMGTs, monoalkyl tetraethers, Messel samples, while GMDs found shale.