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A collection of palaeontological papers 1972 (bulletin 150)

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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 .

Abstract Sedimentary and palaeontological samples from steep, deepwater, escarpments of the Wallaby (`Cuvier') Plateau, a vast marginal plateau with an area of some 100,000km² west of Carnarvon, Western Australia, represent the first collected soft rock geologic data from this immense bathymetric high. The impetus for this frontier, integrated study was to better understand the unresolved geologic history of the Wallaby Plateau, which to date has been hampered by a paucity of real rock data, especially due to difficulties in sampling in 2200 to 5700 m water depths; only modern carbonates, largely altered tholeiitic basalts and volcaniclastic rocks have been recorded previously. Variably fossiliferous to unfossiliferous claystone, siltstone and sandstone samples from 12 southern Wallaby Plateau stations (3015 to 5159 m water depths) range from interpreted paralic to shallow water marine settings, and contain low to moderately diverse assemblages of Bivalvia, Gastropoda, Ostracoda, Foraminifera, palynomorphs, very rare nannofossils, and teleost fish fragments, which collectively point to an age range of latest Berriasian to Barremian-Aptian in the Early Cretaceous that pre-dates, straddles and post-dates the breakup and opening of the Cuvier Abyssal Plain. Seismic imaging of the Wallaby Plateau shows a substantial thickness of both dipping and flat-lying, sub-parallel reflectors beneath parts of the Early Cretaceous Gondwanan break-up unconformity. This information, taken together with the recent identification of Oxfordian-Kimmeridgian foraminifera from the same location, may indicate the presence of pre-breakup sedimentary section beneath parts of the the Wallaby Plateau. Keywords: Systematic palaeontology; Mollusca; Foraminifera; Ostracoda; dinoflagellate cysts; Early Cretaceous; Wallaby Plateau; Australia

While brachiopods from the Devonian of the Canning Basin were first described by Hosking (1933),the only monograph of the fauna is that of Veevers (1959), who also introduced a comprehensive zonation forthe basin. Veevers had at his disposal the earlier collection of Teichert (1949), and the large collections madeby the BMR and WAPET survey parties (see Guppy et al., 1958). The BMR survey also had the benefit of airphotography taken in 1947. Most (but unfortunately not all) of Veevers' localities were marked on the airphotos, which are still held by the palaeontological group of BMR. Veevers quoted air-photo coordinates forhis and the WAPET localities, and I have found these very useful in cross-checking the marked points, wherefield and published numbering systems have diverged. In the process, I discovered several misprints in Veevers'published list. As a recent BMR project to analyse the development of the Canning Basin progressed, it becameapparent that any use of Veevers' brachiopod biostratigraphy was severely limited by uncertainty over the correctstratigraphic position of his localities, in terms of more recently published geological maps (especially Playford& Lowry, 1966). This report is an attempt to address that problem. From all available information, but particularly the air-photos, I have plotted the localities quoted byVeevers onto the current 1:100,000 topographic sheets. Except in areas of little topographic expression thiscould be done with an accuracy equal to that of the map compilations. The results are presented in the firstsection of this report, in which I give as detailed as possible a description of the location of each publishedbrachiopod locality. Coincidentally I have been compiling a catalogue of the BMR holdings of published corals.In the process of providing locality and stratigraphy details I found that there were frequently small discrepanciesfor the heights quoted for localities in measured sections by Hill & Jell (1970) on the one hand, and Veevers(1959) and Veevers & Wells (1961) on the other. I have no way to resolve this, and quote Veevers' figuresherein. I then compared Veevers' published stratigraphic information on the localities against the maps inPlayford & Lowry (1966). These are at the same scale of 1:100,000, although with the old 10,000 yard grid.There were a few topographic discrepancies, but in general this was straightforward. Note was also taken,where possible, of more recent published geological maps (e.g. Druce & Radke, 1979). In making thiscomparison I found relatively few significant changes were needed, other than those resulting from actualchanges in stratigraphic terminology. In the absence of additional biostratigraphic data, I could not generallygo beyond the reassessment of the zonation made by Roberts et al. (1972). However, work on conodont faunasby Nicoll (1980) near a couple of key localities in the Crurithyris apena Zone has led me to establish with someconfidence that that zone must extend into the early Famennian. This partly or completely closes the gapbetween it and the succeeding Nyege scopimus Zone shown by Roberts et al, and is discussed in more detailbelow. Several of the species described by Veevers have since been either fully revised, or at least placed indifferent genera. A few new taxa have also been described. I have brought the results together here in a singlesystematic list, as well as incorporating them in the various lists showing brachiopod distribution, and the tableof zonal distribution.