SUMMARY

Downcore stable isotopic and elemental measurements from ODP Site 1166 indicate changes in OM that correspond to changes in the depositional environment on the Prydz Bay continental shelf since the Late Cretaceous. Large changes in TOC (6.5 to <0.5 wt%) and TN reflect the transition from preglacial sediments with primary OM to highly mature recycled OM deposited during glacial conditions. ¹³C_org and ¹⁵N values indicate a mixture of marine algal and terrestrial sources of OM. Most samples have high C/N values, indicative of terrestrial OM. Although the limited foraminifer ¹³C and ¹⁸O data set precludes any paleoclimatic interpretation, shifts of 0.5 to 1 amplitude in ¹³C and ¹⁸O values of N. pachyderma (s.) may reflect Pliocene to Pleistocene glacial-interglacial cycling in Prydz Bay.