Cretaceous to Cenozoic controls on the genesis of the shelf-incising Perth Canyon

Perth Canyon is Australia's second largest submarine canyon, and its elongate and continental shelf-incising morphology contrasts with Australia's more prolific slope-confined canyons. The canyon's sinuous course extends for 120 km from the continental shelf break (~180 m depth, only 50 km offshore from Perth) to its fan at the foot of the continental slope (~4500 m). This seminar will describe the application of a new, internationally-collaborative mapping approach to capture the complexity of the canyon and to link its modern morphology to subsurface data and thereby reconstruct its geological evolution. Infilled incised valleys found in seismic data beneath the canyon headwall suggest that the canyon initially incised in the Late Cretaceous (around 70 million years ago), and subsequent incisions and canyon activity have since declined in scale. Repeat surveys of the canyon headwall following two relatively large earthquakes in 2018 reveal minimal instability of the seafloor and suggest that the canyon is now less active than in it has been in its geological past.