Geochronology and geochemistry of Palaeozoic intrusive rocks in the Rockvale region, southern New England Orogen, New South Wales

Palaeozoic intrusive rocks of the New England Batholith from the Rockvale district in the southern New England Orogen form three distinct associations: (i) the Carboniferous Rockvale Adamellite, a member of the Hillgrove Suite of deformed S‐type granitoids; (ii) a small I‐type igneous complex on the northwestern margin of the Rockvale Adamellite: several members of this complex have similar chemical compositions to the most mafic members of the Moonbi Suite of New England Batholith I‐types; and (iii) a suite of dyke rocks ranging in composition from calc‐alkaline lamprophyre through hornblende and biotite porphyrite to aplite. Ion‐microprobe U‐Pb zircon analysis indicates intrusion of the Rockvale Adamellite at 303 ±3 Ma (weighted mean 206Pb/238U age; 95% confidence limits). Preliminary investigation of zircon inheritance within the Rockvale Adamellite is consistent with chemical and isotopic indications of derivation of New England Batholith S‐type granitoids from a relatively juvenile protolith. Deforma...

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