The geochemistry and petrogenesis of Carnley Volcano, Auckland Islands, SW Pacific. Issue 4 (2nd October 2018)

• Record Type: Journal Article
• Authors: Gamble, John A.; Adams, Chris J.; Morris, Paul A.; Wysoczanski, Richard J.; Handler, Monica; Timm, Christian
• Is Part Of: New Zealand journal of geology and geophysics. Volume 61:Issue 4(2018)
• Page Start: 480
• Page End: 497
• Publication Date: 2018-10-02
• Subjects: Intra-plate volcanism -- Auckland Islands -- Zealandia -- SW Pacific -- magma petrogenesis; Geology -- New Zealand -- Periodicals; Geology -- Periodicals; Geophysics -- Periodicals; Geofysica; Geologie; Geology; Geophysics; New Zealand; Periodicals; 559.3
• DOI: 10.1080/00288306.2018.1505642
• Languages: English
• ISSNs: 1175-8791

Abstract

ABSTRACT: Intraplate volcanism across Zealandia, South Eastern Australia, the Ross Sea Embayment and Marie Byrd Land in Antarctica define a magmatic province characterised by basalts with elevated 206 Pb/ 204 Pb (18.9–22.5), 87 Sr/ 86 Sr = ∼0.7035, Light Rare Earth enrichment [(Ce/Yb) n > 10], and convex-up mantle normalised incompatible multi-element patterns, peaking at Nb-Ta, with negative K and Pb anomalies. Trace element abundances and ratios (e.g. Zr/Nb, Y/Zr) resemble Ocean Island Basalts (OIB), distinct from Mid-Ocean Ridge Basalt (MORB), suggesting derivation from OIB-like reservoirs. Our preferred scenario envisages partial melting across the garnet-spinel stability fields involving asthenospheric and lithospheric mantle components. Melts accumulate in a column where the deep (asthenospheric) source is PM and the shallower source a melange of PM and subcontinental lithospheric mantle (DMM+1) enriched by carbonatite. Evolution of primary and near-primary magmas is controlled by olivine + clinopyroxene fractionation. Trachybasalts, trachytes and rhyolites show isotopic evidence for interaction with continental crust.