GEOCHEMISTRY OF DUNE FORESET LAMINATIONS

Geochemistry has been used to determine the provenance and diagenetic history of eolian sandstone deposits. However, the grain size, sorting, cementation, and detrital composition change along eolian dune foreset laminae. Documentation of the nature of these changes may be used to generate sampling techniques that will help in acquiring desired data. For example, sampling may be focused in one area or part of the foreset laminae if the average bulk chemistry of the dune or formation is desired, and sampling may be focused in a different location to find abundant zircon grains for provenance studies. Initial documentation of the nature of these changes shows that some geochemical components change fairly predictably along eolian dune foreset laminae between dunes of different sizes and formation of origin. For example, there seems to be a concentration of CaO in the center of dunes and the concentrations of most trace elements drop from the top the bottom of dune foresets. Further analysis and understanding of these changes may be used to generate sampling techniques that will help those interested in eolian dune geochemistry in acquiring desired data. Such an analysis of paleo-dunes in the rock record, when compared to geochemical analysis of modern, active dunes, may also be useful in determining the proportion of eolian dune preservation.