Abstract
Accurate dating of marine sediments is essential to reconstruct past
changes in oceanography and climate. Benthic foraminiferal oxygen
isotope series from such sediments record long-term changes in global
ice volume and deep-water temperature. They are commonly used in the
Plio-Pleistocene to correlate deep ocean records and to construct age
models. However, continental margin settings often display much higher
sedimentation rates due to variations in regional depositional setting
and local input of sediment. Here, it is necessary to create a regional
multi-site framework to allow precise dating of strata. We create such a
high-resolution regional framework to determine the ages of events for
the Northwest Shelf (NWS) of Australia, which was cored by International
Ocean Discovery Program (IODP) Expedition 356. We employ benthic
foraminiferal oxygen and carbon isotopes to construct an
astronomically-tuned age model for IODP Site U1463. The age model is
applied to the IODP Site U1463 downhole-logging natural gamma radiation
(NGR) depth-series, which was then correlated to the NGR of other IODP
sites and several industry wells in the area. The IODP Site U1463
age-depth model provides geologic time anchors for numerous sedimentary
archives on the NWS. This approach allows assigning ages to regional
seismic reflectors and the timing of key climate-related siliciclastic
phases in a predominantly carbonate-rich sequence like the Bare
Formation. Finally, this age model is used to chronologically calibrate
planktonic foraminiferal biostratigraphic datums showing that the
Indonesian Throughflow had shoaled enough during the early Pliocene to
act as biogeographical barrier between the Pacific and Indian Ocean.