Sulfur isotopic composition is a potentially powerful tool for
exploring the timing and mechanisms of organic sulfurization
reactions due to the large downcore porewater sulfur isotope gradient
typically generated by microbial sulfate reduction in anoxic
sediments. The sulfur isotopic composition of bulk pools has been
used to constrain the timing of kerogen and extractable OSC formation
relative to pyrite and other sedimentary sulfur sinks. However,
because OSCs form at different rates and during various stages of
early diagenesis (Vairavamurthy and Mopper, 1987;
Vairavamurthy et al., 1994; Sinninghe Damsté et al., 2007;
Werne et al., 2008), bulk OS potentially represents a mixture of
OSCs with diverse d34S values. Our results represent the first d34S
measurements for individual OSCs in complex lipid extracts from