Early Ordovician conodonts from Barnicarndy 1 stratigraphic well of the Southern Canning Basin, Western Australia

Abstract

Documented here is the systematic description of conodonts from 10 samples collected within the Nambeet Formation in Barnicarndy 1, a deep stratigraphic drillhole located within the Barnicarndy Graben on the southwestern margin of the Canning Basin, Western Australia. The fauna is represented by 22 identifiable species including a new species, Juanognathus? denticulatus sp. nov., and several age-diagnostic taxa. Three biozones extending from the upper Tremadocian to upper Floian (Lower Ordovician) are recognized in these assemblages, including the Jumudontus gananda Biozone, the Oepikodus communis Biozone and the Paroistodus proteus Biozone, all previously recorded from the Samphire Marsh Member of the Nambeet Formation. Identification of this conodont succession has enabled both precise age constraints for this sequence and correlation to other occurrences of the Samphire Marsh Member, and indicates that this unit reaches an apparent thickness of 925 m (from 1345 to 2270 m depth) in Barnicarndy 1. This newly recovered fauna can be well correlated across the basin, such as with Nambeet Formation faunas intersected in the Olympic 1 petroleum well in the northwestern Broome Platform, and from correlative carbonates on the Lennard Shelf along the northern margin of the Canning Basin. Yong Yi Zhen [ yong-yi.zhen@planning.nsw.gov.au ], Geological Survey of New South Wales, W.B. Clarke Geoscience Center, 947-953 Londonderry Road, Londonderry NSW 2753, Australia; Heidi J Allen [ heidi.allen@dmirs.wa.gov.au ]; Sarah K Martin [ sarah.martin@dmirs.wa.gov.au ], Geological Survey of Western Australia, Department of Mines, Industry Regulation and Safety, Mineral House, 100 Plain Street, East Perth WA 6004.