Spatial variations in the composition of turbidites due to hydrodynamic fractionation

Abstract

This study uses measurements from physical experiments to document turbidity currents, which are density currents composed of suspended sediment and water, to be effective at hydrodynamically fractionating minerals on the basis of grain density and grain shape alone, resulting in large-scale spatial variations in the composition of their deposits. While grain composition varies spatially, the population sampled at any one location is hydrodynamically equivalent. Spatial variations in composition of the deposits are modeled using exponential decay functions, which are based on initial concentration of grain types and their respective differences in settling velocity. We further discuss implications of this process for addressing practical geophysical problems, in which mineralogical distributions are important, such as provenance and geochronology studies, subsurface imaging, and predicting bulk properties of subsurface reservoirs. © 2013. American Geophysical Union. All Rights Reserved.