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 com..., , # Dryad dataset

Dataset DOI: [10.5061/dryad.v6wwpzh7k](10.5061/dryad.v6wwpzh7k)

### Files and variables

#### File: supplement_OM.xlsx

This file contains the data related to sediment geochemistry, radiometric dating, and organic matter composition for the linked publication. It is organized into three sheets:

\"AC212_210Pb\" Contains **lead-210 radionuclide data** and sediment characteristics for core AC212, used to estimate sediment accumulation rates.

\"AC212_OM\" Provides **organic matter and isotopic composition data** for samples from core AC212.

\"SURFACE_GRABS\" Includes **surface sediment grab data** collected from multiple locations within and near Astoria Canyon, focusing on organic carbon and isotope characteristics.

##### Variables

* `% TOC` percent total organic carbon
* `210Pb_excess at collection, salt+mud correction (dpm/g)` excess lead-210 activity at the time of sediment collection
* `Auth` author of dataset
* `C:N (atomic)` atomic ratio of carbon to nitrogen
* `Dens...,