Fluvio-deltaic avulsions during relative sea-level fall

A.G. Nijhuis, D.A. Edmonds, R.L. Caldwell, J.A. Cederberg, R.L. Slingerland, J.L. Best, D.R. Parsons, Ruth Alison Joyce Robinson

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)

Abstract

Understanding river response to changes in relative sea level (RSL) is essential for predicting fluvial stratigraphy and source-to-sink dynamics. Recent theoretical work has suggested that rivers can remain aggradational during RSL fall, but field data are needed to verify this response and investigate sediment deposition processes. We show with field work and modeling that fluvio-deltaic systems can remain aggradational or at grade during RSL fall, leading to superelevation and continuation of delta lobe avulsions. The field site is the Goose River, Newfoundland-Labrador, Canada, which has experienced steady RSL fall of around 3-4 mm yr-1 in the past 5 k.y. from post-glacial isostatic rebound. Elevation analysis and optically stimulated luminescence dating suggest that the Goose River avulsed and deposited three delta lobes during RSL fall. Simulation results from Delft3D software show that if the characteristic fluvial response time is longer than the duration of RSL fall, then fluvial systems remain aggradational or at grade, and continue to avulse during RSL fall due to superelevation. Intriguingly, we find that avulsions become more frequent at faster rates of RSL fall, provided the system response time remains longer than the duration of RSL fall. This work suggests that RSL fall rate may influence the architecture of falling-stage or forced regression deposits by controlling the number of deposited delta lobes.
Original languageEnglish
Pages (from-to)719-722
Number of pages4
JournalGeology
Volume43
Issue number8
Early online date10 Jul 2015
DOIs
Publication statusPublished - Aug 2015

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