Distribution of acyclic and cyclic biphytanediols in recent marine sediments from IODP Site C0001, Nankai Trough

摘要

The distribution of acyclic and cyclic biphytanediols, which are the putative breakdown products of glycerol dialkyl glycerol tetraethers (GDGTs), was investigated for recent marine sediments from Nankai Trough, offshore Kii Peninsula. The most abundant diol is tricyclic biphytanediol of which relative abundance is in the range from 32 to 46%. The carbon skeleton of the detected tricyclic biphytanediol is the same as would be expected from crenarchaeol and has two cyclopentane rings and one cyclohexane ring. Based on the molecular structure of crenarchaeol, the tricyclic biphytanediol is considered to be derived not only from crenarchaeol but also from other unknown sources. The ring distributions of biphytanediols are different from those of biphytanes obtained from intact polar lipids by chemical treatment, suggesting that biphytanediols are not solely the diagenetic products of in situ GDGTs.