Foraminiferal signatures of mass transport from the North-West
Continental Shelf off Western Australia, IODP Expedition 356
Abstract
In 2015, Integrated Ocean Discovery Program Expedition 356 drilled along
the margin off Western Australian to investigate the history of the
Indonesian Throughflow (ITF) and its integral role in the development of
global thermohaline circulation and climate. Throughout the expedition,
a suite of foraminiferal analyses were employed wherein planktic
specimens provided biostratigraphy and an incredibly diverse benthic
fauna (~ 260 species) was used to reveal palaeo- water
depth, palaeobathymetric setting and variable conditions at the
sediment-water interface. Benthic foraminiferal biofacies are
particularly sensitive to changes in environmental conditions, have a
rapid turnover and are ideal proxies for monitoring physical and
chemical changes in marine environments. When this information is
combined with lithostratigraphic and other microfossil data, a robust
understanding of past environments and past geological events can be
reconstructed. Shipboard data were used to isolate horizons of interest
for more intense sampling at IODP Site U1461, situated on the North-West
Shelf, at 127 m of water depth. The shipboard data revealed a large
(~150 m-thick) turbidite horizon hosting benthic
foraminifera from a substantially shallower water depth than the horizon
immediately preceding the horizon. We present preliminary foraminiferal
results combined with shipboard sedimentary descriptions to better
constrain the deposit’s occurrence in the biostratigraphic record, use
benthic foraminifera to elucidate the deposit’s sedimentary origins and
link this event with others in the region to investigate potential
catalysts for its deposition.