ORIGIN OF THE APSLEY PARAGNEISS

Abstract

The Apsley paragneiss, a belt of biotitequartz-feldspar gneiss in eastern Ontario, was mapped on a scale of 4 inches = 1 mile. It is shewn that the paragneiss is a member of the Dungannon formation, an important stratigraphic unit of the Grenville series. Fifty hand specimens were collected for modal analyses and ten chip samples were collected for major and minor element analyses. The constituent minerals were separated from the rock for chemical analysis and were examined by optical and X-ray methods. A sodic and a potassic type of paragneiss are recognized. The sodic typo probably is the metamorphic equivalent of sodic graywacke and the potassic type the equivalent of shale interbedded with the graywacke. it is concluded that the metamorphism which affected the Apsley member was approximately isochemical and took place at about 400oC.