How do basin margins record long-term tectonic and climatic changes?

Jinyu Zhang,Zoltán Sylvester,Jacob Covault

doi:10.1130/g47498.1

Abstract

Abstract A long-standing goal of sedimentary geoscience is to understand how tectonic and climatic changes are reflected in basin fill. Here, we use 14 numerical models of continental-scale sediment-routing systems spanning millions of years to investigate the responses of sediment supply and basin sedimentation to changes in uplift and precipitation in the source area. We also investigate the extent to which these signals can be altered by relative sea level (the sum of subsidence and eustasy). In cases of constant relative sea level, sediment supply and margin progradation have similar responses because nearly all of the sediment is transported beyond the coastal plain and continental shelf to the basin margin. Thus, margin progradation can be used as a proxy for sediment supply. However, changes in uplift and precipitation result in different erosional patterns in the source area and different basin-margin depositional patterns. Changes in uplift result in gradual (over several million years) adjustment to new steady states of source-area erosion and margin progradation, whereas changes in precipitation result in abrupt changes in erosion and progradation followed by a return to the initial steady states. In cases of changing relative sea level, sediment storage on the shelf attenuates signals of uplift, but signals of precipitation change can be interpreted in the basin-margin record because climate-induced sediment supply changes are large enough to influence margin progradation. Understanding the relationship between sediment supply and basin-margin progradation, and their linked responses to forcings, improves our ability to interpret signals of environmental change in the stratigraphic record.

Highlights

Sediment supply is considered as the de facto carrier of signals of environmental change from upstream to downstream reaches of sedimentrouting systems (Romans et al, 2016; Sharman et al, 2019)
We focus our analysis on experimental scenarios with acceleration of margin progradation under rising relative sea level because we are interested in the potential for attenuation of uplift and precipitation signals
Our results are especially applicable to field cases in which the role of relative sea-level change on margin progradation is negligible

Summary

INTRODUCTION

Sediment supply is considered as the de facto carrier of signals of environmental change from upstream to downstream reaches of sedimentrouting systems (Romans et al, 2016; Sharman et al, 2019). In spite of decades of research on either the controls on sediment generation and transport (e.g., Densmore et al, 2007; Armitage et al, 2011) or basin-margin development (e.g., Payton, 1977; Wilgus et al, 1988), there has been less work on the relationship between the two and their coupled response to tectonic and climatic forcings (Carvajal et al, 2009). We designed a series of numerical models to better understand the long-term (106–107 yr) relationship between sediment supply and basin stratigraphic evolution under different forcing mechanisms. (2) How does basin-margin evolution respond to changes in tectonic uplift and precipitation in the source area within a catchment?. Results from this study can be used to reconstruct the tectonic and climatic histories of ancient basin-margin records and their source areas

METHODOLOGY

Findings

DISCUSSION AND CONCLUSIONS