Magma sources during Gondwana breakup: chemistry and chronology of Cretaceous magmatism in Westland, New Zealand
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- Magma sources during Gondwana breakup: chemistry and chronology of Cretaceous magmatism in Westland, New Zealand
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and A-type plutonism at 82 Ma is significant as it coincides with the age of the oldest seafloor in the Tasman Sea, therefore it represents magmatism coincident with the initiation of seafloor spreading which continued until 53 Ma. New 40Ar-39Ar ages indicate that the intrusion of mafic dikes in basement lithologies both preceded and continued after the initial opening of the Tasman Sea, including an additional population of ages at 70 Ma. This indicates either a prolonged period of extension-related magmatism that continued >10 Ma after initial breakup,
or two discrete episodes of magmatism during Tasman Sea spreading.
Volumetrically minor Cenozoic within-plate magmatism continued sporadically throughout the South Island and bears a characteristic HIMU (high time integrated U/Pb) signature. A detailed geochemistry and chronological
study of Cretaceous mafic and felsic magmatism is currently in progress and aims to better understand the transition of magma sources from a long lived active continental margin through breakup to a passive setting, and to constrain
the onset and evolution of the chemical characteristics of the magmas and their sources, including the origin of the distinctive HIMU signatures.
|Number of pages||1|
|Publication status||Published - 2013|
Geophysical Research Abstracts Vol. 15, EGU2013-3141-1, 2013, EGU General Assembly 2013
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