Diffusion-zoned pyroxenes in an isotopically heterogeneous mantle lithosphere beneath the Dunedin Volcanic Group, New Zealand, and their implications for intraplate alkaline magma sources
Hayden B Dalton, James M Scott, Jingao Liu, Tod E Waight, D Graham Pearson, Marco Brenna, Petrus Le Roux, J Michael Palin
LITHOSPHERE | GEOLOGICAL SOC AMER, INC | Published : 2017
An important task in assessing the magma source of an intraplate volcanic province is establishing the composition of the underlying lithospheric mantle. Pyroxenes in peridotite xenoliths from the ~10,000 km2 Dunedin Volcanic Group in New Zealand reveal that the underlying lithospheric mantle is chemically and isotopically heterogeneous and has a complex thermal history. Portions of this mantle have light rare earth element-depleted clinopyroxene trace element concentrations and distinctly radiogenic Nd compositions (εNd(20 Ma) ≥ + 15.5) with model depleted mantle ages that are ≥100 m.y. Older than the overlying Jurassic crust (type 1). The Nd isotopic composition of these moderately fertile..View full abstract
Awarded by Foundation for Research Science and Technology Fellowship
Dalton was supported by an Otago Museum Postgraduate Geology Scholarship and an Australasian Institute of Mining and Mineralogy Education Endowment Trust. Pyroxene trace element and isotope analyses were funded by a Foundation for Research Science and Technology Fellowship (contract UOOX1004) and University of Otago Research Grants to Scott, and a Canada Excellence Research Chairs Government of Canada program and a Canada Foundation for Innovation instrumentation grant to Pearson. We thank Y. Luo for providing assistance with orthopyroxene analyses at the University of Alberta. C. Stirling permitted analysis at the Centre for Trace Element Analysis at Otago. We thank S. Pilet and S. Kidder for comments on a draft, and K. Panter and two anonymous reviewers for thorough and constructive reviews.