Preliminary investigations suggest that shales within conventionally-defined rock units in petroleum well Munkarie 1 exhibit characteristic geochemical trace-element signatures. It appears moreover that the Toolachee Formation here can be subdivided into three chemostratigraphic units not otherwise recognisable from well logs. There is no consistent correlation between trace element and organic carbon contents of the analysed samples; although exhaustive correlations are not yet completed, it seems therefore that a major initial aim of this investigation already has been achieved. Potential stratigraphic applications of these geochemical data warrant further work.