Environmental significance of mid- to late Holocene sapropels in Old Man Lake, Coorong coastal plain, South Australia: An isotopic, biomarker and palaeoecological perspective

► Three Holocene sapropel units were deposited in Old Man Lake during increasing aridity. ► TOC, HI, biomarker and isotopic composition lack lateral and secular uniformity. ► Each represents a ∼500 yr interval of elevated diatom and chlorophyte productivity. ► Such sapropel genesis did not necessarily require an anoxic hypolimnion. ► The significance of shallow 'sapropel events' as palaeoclimate proxies is unconfirmed.