Data from: Flood-driven turbidite deposition in a highstand-detached submarine canyon

Turbidites on active margins represent key archives of great earthquakes,
yet turbidity currents triggered by nonseismic events complicate
paleoearthquake records and influence geochemical budgets. Sediment cores
collected from Astoria Canyon address whether ocean-process-triggered
turbidity currents are preserved in “highstand-inactive” canyon
stratigraphy. Detailed analysis of a turbidite-bearing core indicates
fluvial origin on the basis of sedimentology, geochronology, and organic
matter composition. Turbidites are 15 cm thick, graded, and laminated.
Turbidite 210Pb activity is low, and depositional ages align with major
Columbia River floods. Turbidite organic matter is terrestrial and modern
(-26‰ δ13Corg, 18 C:N, ~6 mg lignin per 100 mg OC). These deposits provide
the first direct evidence of turbidite deposition that post-dates the
latest megathrust earthquake in northern Cascadia, with implications
including that highstand stratigraphy preserves nonseismic events,
turbidite composition reflects sediment source, and turbidite deposition
represents a significant component of sediment and carbon accumulation.