The geochemistry of sediments from Little Traverse Bay, Lake Michigan: influence of physical processes

Abstract

Geochemical and textural analyses on 27 surficial sediment samples from Little Traverse Bay, Lake Michigan, were used to define the factors controlling the geochemistry of a pristine lacustrine embayment. Concentrations of 17 elements, carbonate and organic carbon, and textural data were subjected to an R-mode factor analysis. The first four factors determined by this analysis accounted for 89.1% of the variance in the data and were considered to have geochemical significance. We interpreted these factors as: (1) a fine-grained alumino-silicate and organics factor; (2) a heavy mineral factor; (3) a feldspar factor; and (4) a calcium carbonate factor. These factors are largely associated with detrital minerals, indicating that the physical processes occurring in the bay are of dominant importance in controlling the geochemistry of bottom sediments. Factor score distributions showed that the geochemistry of the sediments is largely controlled by bathymetry and by current circulation patterns.