Autogenic delta progradation during sea-level rise within incised valleys

Laure Guerit (1) , Brady Z. Foreman (2) , Chen Chen (3) , Chris Paola (4) , Sebastien Castelltort (5)

1 GR - Géosciences Rennes
2 WWU - Western Washington University
3 UNIGE - Université de Genève = University of Geneva
4 UMN - University of Minnesota [Twin Cities]
5 University of Geneva

Using a simple conceptual model of incised-valley evolution, we show that the classic sequence stratigraphic phenomenon of bayhead deltaic systems can be generated by purely autogenic progradation during the late stage of valley flooding. This transient "auto-advance" event occurs under conditions of constant base-level rise and sediment supply, and results from a strong decrease of in-valley accommodation as base-level rises towards the valley apex. We present a laboratory experiment to illustrate the plausibility of this mechanism and apply it to the Trinity and Brazos rivers incised valleys (Texas, USA) as field case studies. Auto-advance can produce out-of-sequence regressive bayhead diastems during highstands similar to a transient Manuscript submitted to Geology change in allogenic forcing. Combined with other recent studies, our findings support the idea that meso-scale autogenic patterns are ubiquitous in the fluvio-deltaic record, and need to be more extensively incorporated into reconstructions of Earth surface evolution and reservoir models.

Domains: Sciences of the Universe [physics]; Earth Sciences

Laure Guerit, Brady Z. Foreman, Chen Chen, Chris Paola, Sebastien Castelltort. Autogenic delta progradation during sea-level rise within incised valleys. Geology, 2021, 49 (3), pp.273-277. ⟨10.1130/G47976.1⟩. ⟨hal-02992439⟩