Precambrian-Cambrian trace fossils from Western New South Wales

The distribution of trace fossils in the upper part of the Adelaidean succession (Farnell Group) of the Barrier Range near Fowlers Gap is reviewed. Of the main, stratigraphically distinct assemblages, the older from the Fowlers Gap Formation, contains only a few, simple, non-diagnostic, sinuous and branching trails, and is assumed to be of latest Precambrian age. The assemblage in the succeeding Lintiss Vale Formation has a high diversity, mainly of simple behavioural types produced by worm-like animals and molluscs, but lacking arthropod traces. It therefore represents a latest Precambrian or an earliest Cambrian assemblage. A third ichnofauna with simple, sinuous and branching trails is recorded from the Wonominta Beds of the Warratta inlier west of Tibooburra. The occurrence of these trails indicates that at least in the northern areas of ‘basement’ Wonominta outcrop the rocks are no older than latest Precambrian (i.e. the age of the earliest indubitable traces of animal activity) and, judging from the size of some of the trails and longitudinal ribbing on others, are more likely to represent younger deposits of Cambrian or even Early Ordovician age. A fourth assemblage including trace fossils Planolites and Chondrites is reported from the ‘flyschlike’ Copper Mine Range Beds west of White Cliffs. This association has not been described, previously from ‘flysch-like’ deposits older than Early Cambrian.