DEPOSTITIONAL ENVIRONMENTS OF LAKE SUPERIOR SANDS THROUGH GRAIN SIZE ANLYSIS

Abstract

As part of the problem of recognizing and reconstructing paleo"' environments of arenaceous units in western Lake Superior, grain size parameters of modern fluvial, littoral and inner neritic lake sediments have been analyzed., Similar studies are reported from other geographic areas. While environmental field boundaries of certain of these studies. are curved and ill defined, other boundaries are differentiated on a linear basis, the system employed here due to the ea:.se with which such a bo1mdary is defined. Of all available graphs, that of phi deviation versus the diameter was found to be the most successful as it correctly classifies 87.6 per cent of all samples into a fluvial and a non-fluvial field. Further differentiated of non-fluvial fields is displayed. While the 'method presented here is quite functional, correlation with other studies indicates that differing lines of separation between genetic fields must be determined on the local geographic level as predetermined by depositional energy factors.