Deep-water depositional processes and products in the Northern Carnarvon Basin (NW Shelf Australia ) during the Mesozoic and Cenozoic

Contourites are sedimentary features that result from persistent bottom currents and
are commonly found along continental margins. These features provide valuable
information on ocean circulation patterns, climatic changes, and sedimentary processes.
Despite increased recognition, uncertainties remain regarding their morphological
variations, erosion and sedimentation processes, interaction with downslope processes,
and potential as hydrocarbon reservoirs or seals. To address these uncertainties, this study
utilizes two- and three-dimensional seismic reflection data, exploration data, and ODP wells
from the Northern Carnarvon Basin (offshore NW Australia) to investigate several aspects,
including: i) the distribution and abundance of contourite features and the onset of ocean
circulation; ii) the relationship between seafloor morphology and the distribution and
abundance of contourite deposits; iii) the link between ocean circulation shifts and the
opening of oceanic gateways; iv) the interaction between downslope processes and bottom
alongslope currents and their products; v) the formation of contourite drifts along the
continental margin and the modification of sedimentation pathways and accumulation
areas; and vi) the implications of bottom current processes on petroleum system elements.
This seismic interpretation-based study reveals that: (i) from Latest Jurassic to Recent
sediments, deep-water sedimentation in the Northern Carnarvon Basin was largely
influenced by bottom current processes; (ii) the presence of a marginal plateau in the basin
caused deflection and amplification of bottom currents, leading to extensive contourite
drift formation; (iii) the growth of extensive contourite depositional systems is a clear
indication of the opening and closure of oceanic gateways and the onset and modification
of ocean circulation patterns; (iv) the interaction of turbidity and bottom currents caused
hybrid deposits and altered typical sedimentation patterns; (v) erosional and depositional
contourite features shape the continental margin and modify sediment distribution and
deposition from other deep-water processes; and (vi) bottom currents have high potential
for hydrocarbon reservoir formation.