oa Variation in Terrigenous Organic Matter Inputs in a Pleistocene Prograding Continental Margin, Canterbury Basin, New Zealand

IODP Expedition 317 to the Canterbury Basin, New Zealand recovered a 384 m Holocene, Pleistocene and Pliocene sedimentary succession at Site U1354. One of the objectives of this site was to investigate the facies, paleoenvironments, and depositional processes in a proximal setting on a prograding continental margin. In this work, the focus is on the Pleistocene section, where variation in terrigenous organic matter (OM) inputs is hypothesised to have been controlled by sea level fluctuations. The samples are organically lean, with extractable OM = 0.14–0.34 mg/g, and total organic carbon of 0.02–0.91% over the sequence. n-Alkane distributions are dominated by high molecular weight odd-over-even predominance homologues, which is interpreted to be a signal of dominant terrigenous OM input. However the TAR is very variable in the Pleistocene (17–718), suggesting rapid changes in the amount of terrigenous OM reaching the U1354 site, likely reflecting changes in sea level induced by rapid climate fluctuations. The Pr/Ph ratio suggests most sediment was deposited under suboxic bottom water conditions. The presence of ßß hopanes and hopenes shows that the samples are all thermally immature and well preserved. Oleanane abundance is very variable and shows terrigenous OM was mainly derived from angiosperms.