An examination of Ordovician conodont faunas from 42 wells in the Canning Basin from which Ordovician conodont faunas have been recovered has been undertaken to provide biostratigraphic control on Ordovician sedimentation in the basin, especially in the WillaraSub-basin and adjacent Broome Arch areas (Table 1). In addition, preliminary conodontbiostratigraphic data from the Prices Creek Ordovician outcrop area on the northern marginof the basin are also mentioned (Nicoll & others, 1993).
The recovery of conodont elements from samples is highly variable, and few of the wellshave yielded the abundant faunas that are desirable for biostratigraphic control. However, most wells have provided enough data to establish a generalised conodont based biostratigraphy through the interval from the Nambeet Formation to the top of the NitaFormation. Conodonts in the Bongabinni Formation are of Ordovician age but are not included in a formal zone. A number of the samples appear to have been over-acidised whenoriginally processed. The resulting conodonts are etched and discoloured. This also means that some of the conodonts may have been destroyed in the processing. The possibility exists thatnew processing of some of these samples might result in better control of the section.
Material presented includes samples originally prepared and examined by Robert McTavish of WAPET in the 1960's-1970's (McTavish, 1973), samples prepared for Western Mining in the 1980's by Simon Watson (Watson, 1988) and Robert S. Nicoll, determinations by NormanSavage, and material prepared by the Australian Geological Survey (BMR) in the period
1965-1993. Where possible, all previous identifications have been checked for this report. This has not been possible with the samples studied by N.M. Savage (University of Oregon)because the prepared material has not been located.
All samples have been examined for thermal maturation using conodont colour alteration and the results indicated on the well summary sheet and against each sample. The stratigraphic determinations used in this report have been drawn from a number of sources. Most have been taken from the well completion reports, but some have beenmodified to conform with revised interpretations of well stratigraphy .
