Middle Miocene isotope stratigraphy and paleoceanographic evolution of the northwest and southwest Australian margins (Wombat Plateau and Great Australian Bight)

The six main delta13C maxima of the „Monterey Excursion“ between 16.4 and 13.6 Ma and the characteristic stepped increase in delta18O between 14.5 and 13.9 Ma are clearly identified.

The sedimentary record of the shallower ODP Sites 1126 and 1134 [Great Australian Bight (GAB), SWAustralia, 783.8 and 701 m water depth, respectively] is truncated by several unconformities. However, a composite benthic stable isotope curve for these sites provides a first middle Miocene bathyal record for southwest Australia. The delta18O and delta13C curves for Sites 1126 and 1134 indicate a cooler, better-ventilated water mass at ~700 m water depth in the Great Australian Bight since approximately 16 Ma.