High-precision U-Pb ID-TIMS geochronology from the voluminous (≥37,500km3) Devonian Karamea Suite in western New Zealand suggest that the entire suite of ‘S-type’ granites were emplaced within a ~2.1 Ma burst of ‘flare-up’ magmatism. Volume-time relationships with respect to the generation and emplacement of magmas is of particular interest, and suggests that the Karamea Suite occupies an end-member position from the standpoint of catastrophic crustal melting, seemingly requiring a sweet spot of very wet, fertile crust, and a high heat flux from the mantle.
This talk will outline new U-Pb dating, in situ O-Hf-isotopic analyses in zircon, and whole rock geochemistry that indicate that the high magma production rates and rapid crustal melting required the intimate interaction of lower-mid-crustal material with hot asthenospheric magma, necessitating emplacement within an extensional setting.
