03 Mar 2023
 | 03 Mar 2023

The flexural isostatic response of climatically driven sea-level changes on continental-scale deltas

Sara Polanco, Mike Blum, Tristan Salles, Bruce C. Frederick, Rebecca Farrington, Xuesong Ding, Ben Mather, Claire Mallard, and Louis Moresi

Abstract. The interplay between climate-forced sea-level change, sediment erosion and deposition, and flexural adjustments in deep time on passive margin deltas remains poorly understood. We performed a series of conceptual simulations to investigate flexural isostatic responses to high-frequency fluctuations in water and sediment load associated with climatically driven sea-level changes. We model a large drainage basin that discharges to a continental margin to generate a deltaic depocenter, then prescribe synthetic and climatic-driven sea-level curves of different frequencies to assess flexural response. Results show that flexural isostatic adjustments are bidirectional over 100–1000 kyr timescales and are in sync with the magnitude, frequency, and direction of sea-level fluctuations, and that isostatic adjustments play an important role in driving along-strike and cross-shelf river-mouth migration and sediment accumulation. Our findings demonstrate that climate-forced sea-level changes produce a feedback mechanism that results in self-sustaining creation of accommodation into which sediment is deposited and plays a major role in delta morphology and stratigraphic architecture.

Sara Polanco et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-53', Tor Somme, 13 Apr 2023
  • RC2: 'Comment on egusphere-2023-53', Torbjörn Törnqvist, 29 Apr 2023
  • EC1: 'Associate Editor's Comment on egusphere-2023-53', Andreas Baas, 02 May 2023
    • AC3: 'Reply on EC1', Sara Polanco, 30 Jun 2023

Sara Polanco et al.

Sara Polanco et al.


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Short summary
Two-thirds of the world's most populated cities are situated close to deltas. We use computer simulations to understand how deltas sink or rise in response to climate-driven sea-level changes that operate from thousands to millions of years. Our research shows that because of the interaction between the outer layers of the Earth, sediment transport and sea-level changes deltas develop a self-regulated mechanism that modifies the space they need to gain or lose land.