Neoproterozoic interglacial geochemistry & sedimentology of the Tapley Hill Formation in Kingsmill Kreek, Arkaroola, South Australia

Abstract

The break up of the Rodinian supercontinent seems to correspond with the commencement of the Sturtin glaciation which lasted for approximately 60Ma. The Tapley Hill Formation is an interglacial succession of siliciclastic rocks, carbonaceous shales and carbonates deposited in a marine basinal setting before the onset of the Marinoan glacial period. The Kingsmill Creek section of the Tapley Hill Formation is of particular interest because of its lack of diagenesis and metamorphic overprinting. Over 240 rock samples were collected over 481m of section. The samples were exposed to a range of geochemical analyses to look for major and trace elements and carbon and oxygen isotopes. Results confirmed that the Tapley Hill Formation was deposited in an open ocean environment under oxic to sub-oxic conditions below wave base resulting in the oxidation of organic matter. Detrital input was minimal and the rocks have preserved the primary seawater signature. An inorganic carbon excursion at the base of the Tapley Hill Formation agrees with previous findings.