A possible early age for a diprotodon (Marsupialia: Diprotodontidae) fossil from the Papua New Guinea highlands

Menzies, J., Davies, H. L., Dunlap, W. J. and Golding, S. D. (2008) A possible early age for a diprotodon (Marsupialia: Diprotodontidae) fossil from the Papua New Guinea highlands. Alcheringa: An Australasian Journal of Palaeontology, 32 2: 129-147. doi:10.1080/03115510801921895

Author Menzies, J.
Davies, H. L.
Dunlap, W. J.
Golding, S. D.
Title A possible early age for a diprotodon (Marsupialia: Diprotodontidae) fossil from the Papua New Guinea highlands
Journal name Alcheringa: An Australasian Journal of Palaeontology   Check publisher's open access policy
ISSN 0331-5518
Publication date 2008-06-01
Sub-type Article (original research)
DOI 10.1080/03115510801921895
Volume 32
Issue 2
Start page 129
End page 147
Total pages 19
Editor S. McLoughlin
Place of publication Abingdon, Oxford
Publisher Taylor & Francis
Language eng
Subject C1
970104 Expanding Knowledge in the Earth Sciences
040303 Geochronology
Abstract A fossil diprotodon jawbone coated and impregnated with a well-cemented fine breccia or tuff was recovered from weakly consolidated Pleistocene lacustrine sediments near Yonki in the Papua New Guinea highlands. The fine breccia includes angular rock and mineral fragments derived from country rock, accretionary lapilli and clay minerals. It does not include any identifiable primary volcanic material. The presence of accretionary lapilli and lack of volcanic clasts suggests an origin by phreatic eruption—an explosive eruption driven by the violent escape of gas. Minerals in the fine breccia have an age of 13.2 ± 0.2 Ma, middle Miocene, as indicated by 40Ar/39Ar analysis. This is the age of the country rock that was blasted by the phreatic eruption. Igneous activity in the Yonki area is thought to have ceased at 7.4 Ma (younger age limit of Elandora Porphyry; late Miocene), and so it is likely, but not certain, that the phreatic eruption occurred not later than 7.4 Ma. The jawbone, as far as can be told from its poor condition, is dentally similar to the late Pliocene and possibly Pleistocene 'Kolopsis' watutense recovered from other sites in New Guinea. Probably, the jawbone, or the living marsupial, was buried in the fine breccia at the time of the phreatic eruption, and its remains were subsequently reworked by river erosion and redeposited in the lacustrine sediments. Recrystallization and loss of primary texture in some of the bone may be a result of heating at the time of, or preceding, the eruption.
Keyword Miocene
New Guinea
Radiometric Dating
Q-Index Code C1
Q-Index Status Confirmed Code

Document type: Journal Article
Sub-type: Article (original research)
Collections: 2009 Higher Education Research Data Collection
School of Earth Sciences Publications
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Created: Sun, 19 Apr 2009, 06:35:11 EST by Ms Christine Sinclair on behalf of School of Earth Sciences