Source-to-sink stratigraphic modelling

Xuesong Ding, Tristan Salles, Nicolas Flament, Patrice Rey

Software Used:

Badlands 1.0

The sedimentary architecture of basin margins reflects the interplay between the rate of change of accommodation creation (dA) and the rate of change of sediment supply (dS). Understanding the quantitative relationship between changes in dA/dS and depositional patterns can help to constrain the contributing factors of the formation of basin margins. This work investigates the development of stratigraphic sequences in a source-to-sink context using Badlands, and proposes quantitative stratigraphic interpretations based on two well-established techniques: the trajectory analysis method (Helland-Hansen & Hampson, 2009) and the accommodation succession method (Neal & Abreu, 2009; Neal et al., 2016).

Model Setup:

Model setup of a source-to-sink generic case. (a) The initial surface consisting of the mountain range (source area), alluvial plain (transfer zone) and continental margin (sink area). (b) Eustatic sea level and its rate of change over 30 Myr. (c) Distance-dependent stretching factor and the resulting thermal subsidence at 10, 20 and 30 Myr across the continental margin.

Conditions:

Variables	Parameter	value
Non Marine Erodibility	K_e	1.e-7
Rainfall	P [m/a]	2.0
(Rainfall * Area) exponent m	m	0.5
Slope exponent n	n	1.0
Slope Minimum for Flood-plain Deposition	slp_cr	0.001
Non-Marine % Max Deposition	perc_dep	0.75
Land sed. Transport by River	criver	10
Land sed. Transport by Wind	caerial	0.001
Lake/Sea sed. Transport by Currents	cmarine	0.005
No. Time Steps To Distribute Marine Deposits	diffnb	5
Marine % Max Deposition	diffprop	0.9

Results:

Interpretation workflow based on the accommodation succession method. Step 1 includes marking stratal terminations (i.e. toplap, onlap and downlap represented using small arrows) and manually picking the break in slope as offlap break. The refilling of incised channels is shown in red, indicating erosional surfaces. Based on the marked stratal contacts, three stratal stacking trends (solid arrows) and three stratigraphic surfaces (coloured solid lines) are then defined in Steps 2 and 3. The three interpreted stacking patterns are filled with different colours, with their bounding times marked (Step 4). Each stacking pattern reflects the evolving ratio between rate of accommodation creation (δA) and rate of sediment supply (δS). (c) Automatically defined stacking patterns according to the calculated temporal evolution of δA − δS (> 0, < 0 and decreasing, or < 0 and increasing) (d).

Citation:

Ding, X., Salles, T., Flament, N., and Rey, P.: Quantitative stratigraphic analysis in a source-to-sink numerical framework, Geosci. Model Dev., 12, 2571–2585, https://doi.org/10.5194/gmd-12-2571-2019, 2019.

Model URL:

https://github.com/XuesongDing/GMD-models