CSDMS 2015 annual meeting poster QiLi
Exploring the imprint of tectonics on sediment output from a small mountain watershed
Nicole Gasparini, Tulane University, Louisiana, United States.
Kyle Straub, Tulane University, Louisiana, United States.
Abstract:
Changes in tectonics can affect erosion rates across a mountain belt, leading to non-steady sediment flux delivery to fluvial transport systems. This sediment flux record may eventually be recorded in a depositional basin. However, deciphering a tectonic signal from a sedimentary deposit may not be straightforward. Even at the outlet of an erosional watershed the sediment signal produced from time-varying tectonics can already be distorted. In this study, we use the Channel-Hillslope Integrated Landscape Development (CHILD) model to explore how the sediment flux delivered from a mountain watershed responds to non-steady uplift. The modeled uplift rate in each experiment varies between a high and low value. Between experiments we vary the duration of the high and low uplift intervals, but not the magnitude of the uplift rates. We observe that (1) sediment flux does not respond to a change in uplift rate immediately unless the erosional system has reached steady state, and in some cases the sediment flux is out of phase with the uplift rate; (2) the duration of the high or low uplift rate influences the amount of time it takes for the sediment flux to begin increasing (decreasing) after an increase (decrease) in uplift rate; (3) there are cases in which the sediment flux does not record changes in the uplift rate. All of these observations highlight the difficulty in accurately reconstructing the tectonic history from the sediment flux history, let alone from a sedimentary deposit. Results from this study will help to constrain what tectonic signals may be evident in the sediment flux delivered from an erosional system and therefore have the potential to be recorded in stratigraphy, ultimately improving our ability to interpret stratigraphy.
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