Abstract
The δ34S of seawater sulfate reflects processes operating at the nexus
of sulfur, carbon, and oxygen cycles. However, knowledge of past
seawater sulfate δ34S values must be derived from proxy materials that
are impacted differently by depositional and post-depositional
processes. We produced new timeseries estimates for the δ34S value of
seawater sulfate by combining 6710 published data from three sedimentary
archives—marine barite, evaporites, and carbonate-associated
sulfate—with updated age constraints on the deposits. Robust features
in multiple records capture temporal trends in the δ34S value of
seawater and its interplay with other Phanerozoic geochemical and
stratigraphic trends. However, high-frequency discordances indicate that
each record is differentially prone to depositional biases and
diagenetic overprints. The amount of noise, quantified from the
variograms of each record, increases with age for all δ34S proxies,
indicating that post-depositional processes obscure detailed knowledge
of seawater sulfate’s δ34S value deeper in time.