ABSTRACT

Previous work on the use of detrital quartz as an index to provenance is critically examined, and it is concluded that the only two valid criteria advanced are 1) composite nature of polygranular fragments, and 2) shape of monogranular particles. The present study develops the second criterion, an attempt being made to group grains as either igneous or metamorphic solely on the basis of shape. Measurement of elongations (long axis/short axis) of several thousand quartz grains from sandstones of each of two formations revealed a statistical difference in the grain shapes of the two sandstones. Grains from several badly weathered crystalline rocks were also measured, and it was found that the average elongation for the grains of a granite was less than that for the grains of a schist By analogy, it is concluded that the grain shape difference between the two sandstones is due to their derivation from different source rocks.