Developing a radiometrically-dated chronologic sequence for Neogene biotic change in Australia, from the Riversleigh World Heritage Area of Queensland Jon Woodhead a, ⁎, Suzanne J. Hand b , Michael Archer b , Ian Graham b , Kale Sniderman a , Derrick A. Arena b,c , Karen H. Black b , Henk Godthelp b , Philip Creaser b , Elizabeth Price b a School of Earth Sciences, The University of Melbourne, Melbourne, VIC 3010, Australia b School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia c Associated Scientific Limited, Australia abstract article info Article history: Received 3 September 2014 Received in revised form 14 October 2014 Accepted 22 October 2014 Available online xxxx Handling Editor: M. Santosh Keywords: U–Pb geochronology Riversleigh Speleothem Biocorrelation Radiometric U–Pb ages are presented for the Riversleigh World Heritage fossil mammal site in northwestern Queensland, Australia. The ages are determined on speleothems which are generally found in intimate or well-documented association with fossil remains and thus can be assumed to record the age of the latter with a high degree of confidence. The new ages encompass the early (18.2–16.5 Ma) and middle Miocene (15.1– 13.5 Ma) deposits at Riversleigh in addition to the younger Rackham's Roost Site which returns early Pleistocene ages. Together, these provide a robust chronological framework for the interpretation of Neogene biotic change in Australia that has, until now, relied almost entirely upon biocorrelative techniques. In particular they permit closer investigation of links between other regions/faunas and allow comparison with other records of climatic and environmental change. This is the first documented example of a methodology that has widespread potential application across many continents and throughout much of Earth history. © 2014 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved. 1. Introduction Australia is one of the last continents to have a securely dated frame- work for the evolution of its Cenozoic terrestrial biotas. Until now, the vast majority of Australia's mammal-bearing deposits have been dated by biocorrelation, anchored by little more than half a dozen radiometric dates for the entire continent. Some regions have superpositional biotas but most of these are relatively limited in taxic biodiversity making biocorrelation much more difficult. The oldest Australian Cenozoic terrestrial mammal-bearing assem- blage is the Tingamarra Local Fauna (LF) 1 from southeastern Queens- land, radiometrically dated at (minimally) 54.6 Ma (Godthelp et al., 1992). This is the only terrestrial mammal-bearing assemblage for the whole continent in the gap between the early Cretaceous and the late Oligocene (Black et al., 2012a). The only late Oligocene assemblages that have been radiometrically dated are those of the upper Etadunna Formation in South Australia, to which a single reported date has been tentatively applied (Woodburne et al., 1994; see also below). Australia's many Miocene assemblages include the most diverse mammal faunas known for the pre-Quaternary Cenozoic. Only one relatively impoverished assemblage has been radiometrically dated: the sparse early Miocene Geilston Bay LF of Tasmania (Tedford and Kemp, 1998). However, the early Miocene Wynyard LF (one taxon) of Tasmania, the middle Miocene Batesford Quarry LF of Victoria with one mammal taxon, and the mammal-poor late Miocene Beaumaris LF of Victoria (Black et al., 2012a) have been dated on the basis of marine biocorrelation. Among Pliocene assemblages, the early Pliocene Hamilton LF from northwestern Victoria (Turnbull and Lundelius, 1970; Turnbull et al., 2003), the early Pliocene Sunlands LF of South Australia (Pledge, 1987), the middle Pliocene Bluff Downs LF from northeastern Queensland (Rich et al., 1991; Mackness et al., 2000; Mackness and Archer, 2001) and the late Pliocene Awe LF of New Guinea (Plane, 1967; Hoch and Holm, 1986) have been radiometrically dated. In distinct contrast, there are hundreds of radiometrically dated Pleistocene assemblages. Developing an accurate and precise chronology for Australia's Miocene assemblages is critical for many reasons. First, the majority of Australia's pre-Quaternary mammals and mammal assemblages are now known from this epoch. Second, these assemblages document an overlap and gradual transition between relatively archaic groups (e.g., ilariids and wynyardiids) that were common in the late Oligocene and relatively more derived groups (e.g., macropodids and vombatids) that dominated the Pliocene and Quaternary. Third, the history of climate change impacting the continent during this period included a Gondwana Research xxx (2014) xxx–xxx ⁎ Corresponding author. Tel.: +61 3 83446821. E-mail address: jdwood@unimelb.edu.au (J. Woodhead). 1 LF: a faunal assemblage from a specific locality or series of geographically and stratigraphically related localities that are interpreted to represent the same palaeocommunity. GR-01342; No of Pages 15 http://dx.doi.org/10.1016/j.gr.2014.10.004 1342-937X/© 2014 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Gondwana Research journal homepage: www.elsevier.com/locate/gr Please cite this article as: Woodhead, J., et al., Developing a radiometrically-dated chronologic sequence for Neogene biotic change in Australia, from the Riversleigh World Heritag..., Gondwana Research (2014), http://dx.doi.org/10.1016/j.gr.2014.10.004