- GeoRef, Copyright 2006, American Geological Institute.
Twenty-nine samples of shale and twelve of sandstone were collected from the Vanoss Fm. (Pennsylvanian) of Oklahoma, use in sodium bisulfate, and analyzed for feldspar types and abundances as a function of increasing distance from a known granitic source. Normative total feldspar, orthoclase, and calculated orthoclase and perthite percentages in the Q + F fraction of the 3.5 phi -4.0 phi sediment in the shales decrease exponentially with increasing distance from their source from amounts exceeding 50% 40 km from the granite source to values consistently below 5% 112 km from the source. No diagenetic effects are evident. Percentages of normative albite (in oligoclase grains), however, show irregular variations among samples at distances of less than 60 km from the granite (12%-36%) and then drop precipitously to values of less than 5% because of diagenesis. The percentages of feldspar in the 3.5 phi -4.0 phi fraction in fused samples of Vanoss sandstones are consistently higher in the shales than in associated sandstones, even for the feldspar varieties that suffered very little diagenesis. This proved to be an artifact of the fusion technique as applied to ancient sedimentary rocks and indicates that great caution is required in the interpretation of data obtained by sodium bisulfate fusion .