ABSTRACT

The Parry Group conformably overlies the Tamworth Group in the Tamworth Trough sequence of northeastern New South Wales. It consists dominantly of olive-green chloritic mudstones together with lithic labile graywacke and sandstone, feldspathic graywacke, argillaceous and lithographic limestone, and polymictic conglomerate. The detritus is thought to have been derived from an andesitic island arc which contained local exposures of older sediments, granite, and acid volcanics. The lithic labile arenites consist dominantly of volcanic rock fragments and plagioclase, generally albitised but occasionally unaltered andesine, with some clinopyroxene, amphibole, chlorite, opaques, and minor quartz. The modal composition of these rocks shows a restricted range of variation through the sequence which suggests that changes of composition of source areas were not marked during the period of deposition of the sequence.