Palaeontological and biostratigraphic studies for each Phanerozoic system are briefly summarised for the entire Canning Basin, with emphasis on the Palaeozoic. Biostratigraphic analysis of sixkey wells on the Lennard Shelf (May River 1, Langoora 1, Meda 1, Meda 2, Blackstone 1 and.Mimosa 1) are given in an Appendix. A synthesis of this information has led to the identificationof ten major stratigraphic breaks within the Palaeozoic succession on the Lennard Shelf:
1.The entire Cambrian Period and most of the Tremadocian.
2.Much of the Silurian and the Early Devonian (resulting from an Early Silurian age for theWorral Formation, and a Late Ordovician - earliest Silurian age for the underlying CarribuddyGroup).
3.Within the early Famennian (a break of variable duration in different parts of the study area).
4.WI& the late Famennian (corresponding to the Upper postera, and Lower expansa conodontZones).
5.Within the latest Famennian (Strunian - possibly representing the global sea-level fall in theMiddle praesulcata Zone, just prior to the WC boundary).
6.Within the latest Toumaisian-early Visean (between the Laurel Formation and the AndersonFormation; the least plausible stratigraphic break).
7.Within the latest Visean-early Namurian (representing the maculosa assemblage).
8.The late Westphalian and most or all of the Stephanian (representing the birkheadensis Zone).
9.The early part of the Sterlitamaldan Stage (between the base of the Nura Nura Member of thePoole Sandstone, and the top of the Grant Group.
10.The latest Permian (Dorashamian = Changhsingian) Stage (representing the
Protohaploxypinus microcotpus Zone; between the upper part of the Hardman Formation and thelower part of the Blina Shale).
Biostratigraphic control provided by conodonts, ostracods, naicrovertebrates and spores hasunderpinned AGSO sequence analyses of seismic and well data for a new interpretation of theoutcropping and subsurface Late Devonian reef complexes. Revised ages effect theunderstanding of the petroleum resource potential in the Ordovician sequence. Some formationswithin the Carribuddy Group may behave as effective seals to source and reservoir rocks in theNita Goldwyer Formations.
