Constraints on the creation of a HIMU-Like isotopic reservoir beneath New Zealand
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Constraints on the creation of a HIMU-Like isotopic reservoir beneath New Zealand. / van der Meer, Quinten; Waight, Tod Earle; Scott, James.
In: Mineralogical Magazine, Vol. 77, No. 5, 2013, p. 2392.Research output: Contribution to journal › Conference abstract in journal › Research › peer-review
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T1 - Constraints on the creation of a HIMU-Like isotopic reservoir beneath New Zealand
AU - van der Meer, Quinten
AU - Waight, Tod Earle
AU - Scott, James
N1 - Goldschmidt conference, Florence Italy. Published in Mineralogical Magazine, 77(5) 2392
PY - 2013
Y1 - 2013
N2 - The New Zealand microcontinent (Zealandia) formed as the active eastern margin of Gondwana. Upon cessation of subduction at ~110 Ma, extension led to opening of the Tasman Sea at 82 Ma, preceded by the formation of metamorphic core complexes, the opening and filling of halfgraben structures and the intrusion of mafic dikes (~88 to 68 Ma). Subsequently, Zealandia has been punctuated by volumetrically minor, intermittent yet widespread intraplatemagmatism from ~100 Ma through to recent times. This magmatism has typical OIB-like trace element abundances and radiogenic isotope compositions that trend towards a HIMU (high time integrated U/Pb) end member mantlecomposition. Recent publications have argued that that the intraplate OIB-like magmatism is not related to a mantle plume but is rather formed by delamination of mantle lithosphere, replacement by asthenosphere and associated partial melting. The variably diluted HIMU signature is interpreted to be the result of mixing between depleted mantle bearing a HIMU component with an Enriched Mantle or continental crust component.New geochemical and isotopic analyses suggest the dike swarms also have an OIB-like chemistry. Initial Pb isotopic compositions of the dikes however are more similar to Pacific MORB. It is possible that the HIMU-like component inZealandia is a result of trace element enrichment (with high U/Pb and Th/Pb) of a depleted mantle melt region in the Cretaceous. This source has remained stable beneath Zealandia while Pb ingrowth proceeded rapidly in U-Th richdomains. Repeated melt extraction from this source resulted in the intraplate magmatism with HIMU-like Pb isotopes. Isotopic data from peridotite xenoliths in the Cenozoic intraplate volcanoes reveal that the spinel facies lithosphericmantle beneath Zealandia also has high 206Pb/204Pb ratios. Lithospheric peridotite mantle is a potential source component for the intraplate basalts, which require an additional garnet rich source component.
AB - The New Zealand microcontinent (Zealandia) formed as the active eastern margin of Gondwana. Upon cessation of subduction at ~110 Ma, extension led to opening of the Tasman Sea at 82 Ma, preceded by the formation of metamorphic core complexes, the opening and filling of halfgraben structures and the intrusion of mafic dikes (~88 to 68 Ma). Subsequently, Zealandia has been punctuated by volumetrically minor, intermittent yet widespread intraplatemagmatism from ~100 Ma through to recent times. This magmatism has typical OIB-like trace element abundances and radiogenic isotope compositions that trend towards a HIMU (high time integrated U/Pb) end member mantlecomposition. Recent publications have argued that that the intraplate OIB-like magmatism is not related to a mantle plume but is rather formed by delamination of mantle lithosphere, replacement by asthenosphere and associated partial melting. The variably diluted HIMU signature is interpreted to be the result of mixing between depleted mantle bearing a HIMU component with an Enriched Mantle or continental crust component.New geochemical and isotopic analyses suggest the dike swarms also have an OIB-like chemistry. Initial Pb isotopic compositions of the dikes however are more similar to Pacific MORB. It is possible that the HIMU-like component inZealandia is a result of trace element enrichment (with high U/Pb and Th/Pb) of a depleted mantle melt region in the Cretaceous. This source has remained stable beneath Zealandia while Pb ingrowth proceeded rapidly in U-Th richdomains. Repeated melt extraction from this source resulted in the intraplate magmatism with HIMU-like Pb isotopes. Isotopic data from peridotite xenoliths in the Cenozoic intraplate volcanoes reveal that the spinel facies lithosphericmantle beneath Zealandia also has high 206Pb/204Pb ratios. Lithospheric peridotite mantle is a potential source component for the intraplate basalts, which require an additional garnet rich source component.
U2 - 10.1180/minmag.2013.077.5.22
DO - 10.1180/minmag.2013.077.5.22
M3 - Conference abstract in journal
VL - 77
SP - 2392
JO - Mineralogical Magazine
JF - Mineralogical Magazine
SN - 0026-461X
IS - 5
ER -
ID: 120128948