Signature of non-locality in depositional systems

Signature of non-locality in depositional systems: Implications for modeling and
interpretation of stratigraphic records
Vamsi Ganti, Kyle Straub, Efi Foufoula-Georgiou and Mark Meerschaert
Compensational stacking which is defined as the tendency of sediment transport
processes to fill-in topographic lows through deposition is a concept widely used in the
interpretation of the stratigraphic records. Recently, a new metric called the
“compensation index” was proposed to quantify the degree of compensational stacking in
any depositional system and power-law trends were used to describe the decrease in
standard deviation of sedimentation/subsidence with increasing averaging distance. An
explanation of the observed power-law trends was given in terms of the correlation
between elevation increments in time. In this work, we present a possibility of an
alternative explanation for the observed power-law trends using high temporal resolution
data for a delta in an experimental basin undergoing relative subsidence. We demonstrate
that heavy-tailed distributions for periods of non-sedimentation and magnitudes of
sedimentation events can lead to the observed phenomenon with the compensation index
dependent on the tail-index of the two distributions. Further, we show that a truncated
Pareto distribution and a stable density provide a good fit for the densities of periods of
non-sedimentation and magnitudes of sedimentation in the experimental basin. Finally,
implications of the experimentally observed heavy-tails are discussed in the context of
developing transport models in depositional systems.