Volume and recurrence of submarine‐fan‐building turbidity currents

Abstract

Submarine fans are archives of Earth-surface processes and change, recording information about the turbidity currents that construct and sculpt them. The volume and recurrence of turbidity currents are of great interest for geohazard assessment, source-to-sink modelling, and hydrocarbon reservoir characterization. Yet, such dynamics are poorly constrained. This study integrates data from four Quaternary submarine fans to reconstruct the volume and recurrence of the formative turbidity currents. Calculated event volumes vary over four orders of magnitude (10 5 to 10 9 m 3 ), whereas recurrence intervals vary less, from 50 to 650 years.The calculated turbidity-current-event volume magnitudes appear to be related to slope position and basin confinement. Intraslope-fan deposits have small event volumes (ca 10 6 m 3 ) while ponded-fan deposits have very large event volumes

The evolution of submarine slope-channel systems: Timing of incision, bypass, and aggradation in Late Cretaceous Nanaimo Group channel-system strata, British Columbia, Canada

“…Repeat bathymetric surveys and direct monitoring provide evidence for multiphase sediment-transport processes in many active unfilled canyons and slope-channel systems (Conway et al, 2012;Gales et al, 2019;Vendettuoli et al, 2019). For example, local deposition of sediment by regular turbidity currents is commonly observed in slope channels but these deposits are eventually flushed downslope during less-frequent, larger-magnitude flow events (Jobe et al, 2018;Paull et al, 2018;Stacey et al, 2019). In some cases, such net-transport conditions can persist for millions of years (e.g., 5 m.y.…”

“…Our data set sheds light on the fidelity of the stratigraphic record and also provides temporal context for the commonly recognized stratigraphic evolution of submarine channels. Horizontally to vertically aligned channelform stacking patterns are observed globally over a wide range of temporal and spatial scales (spanning distances up to 20 km laterally and >1000 m vertically, over time scales ranging from 10 4 to 10 6 yr; Jobe et al, 2018;Sansom, 2018). Although calculated durations may not be directly applicable to systems of varying longevity, their relative comparison is informative and potentially useful for evaluating the temporal significance of this pattern in other deposits.…”

Quantifying tabularity of turbidite beds and its relationship to the inferred degree of basin confinement

“…Calculations of flow volumes and transported grain sizes 18 (including the fraction of clay) requires very detailed dataset collected for this type of purpose, 19 especially in unconfined systems (e.g. Jobe et al, 2018). Finally, these first order controls will be 20 themselves the result of changes in the boundary condition or in the development stage of a 21 turbidite system (e.g.…”

Controls on submarine channel-modifying processes identified through morphometric scaling relationships

“…Turbidity currents are driven by gravity acting on this excess density, and contrary to fluvial flows, cannot travel downslope without entrained sediment. Turbidity currents are thought to typically last hours or days, although week-long flows have been documented (Cooper et al, 2013;Azpiroz-Zabala et al, 2017), and occur relatively infrequently in deep-water settings (a few times per year to every few hundred years; Paull et al, 2014;Stevens et al, 2014;Jobe et al, 2018). This contrasts the perennial flows of many fluvial channels, although highly variable discharge in some rivers may result in relatively few flows exhibiting disproportionate control on channel morphology (Wolman and Miller, 1960;Plink-Björklund, 2015).…”