Late Ordovician allochthonous limestones in Late Silurian Barnby Hills Shale, central western New South Wales

Y. Y. Zhen*, I. G. Percival, J. R. Farrell

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    13 Citations (Scopus)


    Allochthonous limestone blocks exposed in the Eurimbla area, west of the Mitchell Highway between Molong and Wellington, are substantially older than the enclosing Bamby Hills Shale of Late Silurian age. Nine of the blocks yielded a diverse Late Ordovician conodont fauna, dominated by Panderodus gracilis, Belodina confluens, Periodon grandis, Paroistodus? nowlani and Yaoxianognathus? tunguskaensis. Occurrence of Taoqupognathus blandus in seven sampled blocks indicates an early Eastonian (Ea2) age, although rare Taoqupognathus tumidus in one suggests an extension into the late Eastonian (Ea3). These age determinations are confirmed by the presence of a silicified brachiopod fauna with typical elements (predominantly Mabella halis and Doleroides mixticius) of the previously defined fauna B of Eastonian 2 age. The conodont and articulate brachiopod faunas from the Eurimbla blocks are comparable with those from autochthonous limestones of Eastonian age elsewhere in the Molong Volcanic Belt, in particular the Bowan Park Group, except for occurrence of the conodont Webbygnathus munusculum and brachiopod Sowerbyella billabongensis which, in the Lachlan Orogen, are otherwise known only from the Junee-Narromine Volcanic Belt to the west. The allochthonous blocks may have been subject to one or more episodes of erosion and redeposition, prior to final emplacement in the Barnby Hills Shale.

    Original languageEnglish
    Pages (from-to)29-51
    Number of pages23
    JournalProceedings of the Linnean Society of New South Wales
    Publication statusPublished - Jan 2003


    • Allochthonous limestones
    • Bamby Hills Shale
    • Brachiopods
    • Conodonts
    • Late Ordovician
    • Late Silurian

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