The oxygen-bearing geolipids in the Lucaogou shale of Upper Permian, Santanghu Basin, China

An abundant series of C8-C27 γ-n-alkyl-γ-butyrolactones, γ-isoprenoid-alkyl-γ-butyrolactones with side chains consisting of 1-3 isoprenoid units, and C8-C25 δ-n-alkyl-δ-valerolactones were identified in the Upper Permian shale of the Lucaogou Formation of the Santanghu Basin (270-250 Ma) in eastern Xinjiang, China. The possible origin of these compounds is discussed, particularly of those which had not been identified previously as geolipids in Permian rocks. Contributions from microalgae such as eustigmatophytes and transformation of organic matter by bacteria were likely sources of these oxygen-bearing geolipids.