Conodonts and tabulate corals from the Upper Ordovician Angullong Formation of central New South Wales, Australia

Abstract

Zhen, Y.Y., Wang, G.X. & Percival, I.G., August 2016. Conodonts and tabulate corals from the Upper Ordovician Angullong Formation of central New South Wales, Australia. Alcheringa 41, xxx–xxx. ISSN 0311-5518.

The Angullong Formation is the youngest Ordovician unit exposed in the Cliefden Caves area of central New South Wales. Its maximum age is constrained by a Styracograptus uncinatus graptolite Biozone fauna at the very top of the underlying Malongulli Formation, but the few fossils previously reported from higher in the Angullong Formation are either long-ranging or poorly known. From allochthonous limestone clasts in the middle part of the formation, we document a conodont fauna comprising Aphelognathus grandis, A. solidum, Aphelognathus sp., Aphelognathus? sp., Belodina confluens, Drepanoistodus suberectus, Panderodus gracilis, Panderodus sp., Phragmodus undatus, Pseudobelodina inclinata and Pseudobelodina? sp. aff. P. obtusa, which supports correlation with the Aphelognathus grandis Biozone (late Katian) of the North American Midcontinent succession. The species concepts of Aphelognathus and Pseudobelodina are reviewed in detail. Associated corals are exclusively tabulates, dominated by agetolitids, including Agetolites angullongensis sp. nov., Heliolites orientalis, Hemiagetolites breviseptatus, Hemiagetolites sp. cf. H. spinimarginatus, Navoites sp. cf. N. circumflexa, Plasmoporella bacilliforma, P. marginata, Quepora sp. cf. Q. calamus and Sarcinula sp. Affinities of the coral fauna from the Angullong Formation are closer to faunas from northern NSW and northern Queensland than to the locally recognized Fauna III of late Eastonian age in central NSW. We propose a subdivision of Fauna III to account for this difference, with the late Katian Fauna IIIB characterized by the incoming of agetolitid corals. The currently known distribution of representatives of this group with adequate age constraints suggests that agetolitids possibly originated in North China, subsequently migrating to Tarim, South China and adjacent peri-Gondwanan terranes while also spreading eastward to northern Gondwana, where they progressively moved through eastern Australia to reach the central NSW region by the early Bolindian.

Yong Yi Zhen* ([email protected]) and Ian G. Percival ([email protected]), Geological Survey of New South Wales, W.B. Clarke Geoscience Centre, 947–953 Londonderry Road, Londonderry, NSW 2753, Australia; Guangxu Wang ([email protected]), State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, 39 East Beijing Road Nanjing 210008 PR China.

Key words:

• Conodonts
• tabulate corals
• Ordovician
• Katian
• biostratigraphy
• palaeobiogeography
• New South Wales

Acknowledgements

G.X. Wang’s visit to Australia and field trip in central NSW in November 2014 were jointly funded by the National Natural Science Foundation of China (Grants no. 41521061 and 41290260), the State Key Laboratory of Palaeobiology and Stratigraphy (LPS) (Grant no. Y526050104) and the Geological Survey of New South Wales. Paul Meszaros and Michael Bruce (Geological Survey of New South Wales) respectively assisted with conodont sample acid leaching and residue separation, and coral thin-section preparation. SEM studies of conodonts were carried out at the Electron Microscope Unit of the Australian Museum. Barry Webby and Chris Barnes are thanked for their constructive and helpful comments. Y.Y. Zhen and I.G. Percival publish with the permission of the Executive Director, Geological Survey of New South Wales. This is a contribution to IGCP Project 591: The Early to Middle Paleozoic Revolution.