Stratigraphy,sedimentology, structure and tectonics of Lower Ordovician and Devonian strata of South Mootwingee,Darling Basin,western New South Wales

K‐Ar age measurements using the ⁴⁰Ar/³⁹Ar total fusion technique on nephrite from two occurrences in the Great Serpentine Belt southeast of Tamworth yielded ages of 273 ± 5.8 and 280 ± 5.6 m.y. The K‐Ar ages indicate that tectonic emplacement, during which the nephrite was produced as a reaction product between ultra‐mafic rock and country rock, occurred early in the Permian about 275–280 m.y. ago.     

Stratigraphy,structure and tectonics of Lower Ordovician and Devonian strata of the central part of the Wonominta Block,western New South Wales

K‐Ar age determinations on granites from Central Queensland support the conclusions of field mapping, that the intrusives of the Anakie High are generally older than the rocks of the Drummond Basin. Results on granites from the Bowen‐Collinsville region indicate that they pre‐date most of the Bowen Basin sediments. Four ages are reported for basement rock from bore‐cores in the Great Artesian Basin. They confirm Precambrian basement to the south of the Mt. Isa‐Cloncurry area, and suggest possible Precambrian in the Long‐reach Spur. Two samples from the Nebine Ridge give Lower Carboniferous results. A previous report of Permian basement in the Surat Basin has been shown to be incorrect.