oa ORIGIN AND FATE OF ISOPRENOID GLYCEROL DIALKANOL DIETHERS IN SEDIMENTS FROM LATE MIOCENE TO MID-EOCENE

In the past decade especially, more light has been shed on the high diversity in structures of isoprenoid glycerol dialkyl glycerol tetraethers, providing improved insight into both their origin and fate in different settings. A closely related set of isoprenoidal lipids, isoprenoid glycerol dialkanol diethers (isoGDDs), were reported by Liu at al. (2012a ; 2012b ) in marine subsurface sediments. In this study we investigated the occurrence and distribution of GDGTs and GDDs in sediment cores from 3 well-known organic rich sampling sites, Messel oil shale, Vena del Gesso evaporites and Monterey sediments. The strong correlation in abundance and isomer distributions between isoGDDs and isoGDGTs strongly suggest that isoGDDs predominantly have a diagenetic origin, forming by glycerol cleavage of isoGDGTs. The rate at which this happens likely depends upon many factors. Further work will be carried out in order to ascertain the link between these two lipid classes.