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 [[email protected]], Geological Survey of New South Wales, W.B. Clarke Geoscience Center, 947-953 Londonderry Road, Londonderry NSW 2753, Australia; Heidi J Allen [[email protected]]; Sarah K Martin [[email protected]], Geological Survey of Western Australia, Department of Mines, Industry Regulation and Safety, Mineral House, 100 Plain Street, East Perth WA 6004.

Keywords:

• Conodonts
• Early Ordovician
• biostratigraphy
• Canning Basin
• Western Australia.

Acknowledgements

Barnicarndy 1 was drilled within the Martu Native Title area, with the approval of the Western Desert Lands Aboriginal Corporation (WDLAC). As a project under the Geoscience Australia’s (GA) Exploring for the Future initiative, establishing detailed biostratigraphic and chronostratigraphic framework in the Barnicarndy 1 deep stratigraphic drillhole has been undertaken by the Geological Survey of Western Australia (GSWA) in collaboration with GA, Geological Survey of New South Wales (GSNSW) and other agencies nationwide. Drilling of deep stratigraphic drillhole Barnicarndy 1 was funded by GA’s Exploring for the Future initiative and operated by GSWA. Yong Yi Zhen’s study of the conodont fauna was supported by GSNSW. Conodont samples were processed at Macquarie University with funding from the GSWA’s Exploration Incentive Scheme. SEM images were prepared in the Electron Microscope Unit of Macquarie University with assistance from Sue Lindsay. Guillermo Albanesi and an anonymous referee are thanked for their careful and constructive reviews of the manuscript. This is a contribution to IGCP Project 735 (Rocks and the Rise of Ordovician Life) and IGCP Project 668 (Equatorial Gondwana History and Early Palaeozoic Evolutionary Dynamics). Yong Yi Zhen publishes with the permission of the Executive Director, GSNSW. Heidi Allen and Sarah Martin publish with permission of the Executive Director, GSWA.

Disclosure statement

No potential conflict of interest was reported by the authors.