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| Titel: |
Geochronology and geochemistry of Palaeozoic intrusive rocks in the Rockvale region, southern New England Orogen, New South Wales |
| Auteur: |
Kent, A. J. R. |
| Verschenen in: |
Australian journal of earth sciences |
| Paginering: | Jaargang 41 (1994) nr. 4 pagina's 365-379 |
| Jaar: |
1994-08 |
| Inhoud: |
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. Deformation of the Rockvale Adamellite occurred after complete crystallization of the pluton and prior to emplacement of dykes and I-type intrusives. K-Ar biotite and hornblende ages show broadly synchronous intrusion of I-type magmas and lamprophyre dykes at ca 255 Ma, indicating that mantle magmatism associated with lamprophyres was contemporaneous with the crustal production of I-type melts. Chemical similarities between the most mafic Moonbi Suite members and calc-alkaline lamprophyres may also indicate a direct mantle contribution to some I-type magmas. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 4 van 11 gevonden artikelen
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