Magmatism during Gondwana break-up: new geochronological data from Westland, New Zealand

Newly determined Late Cretaceous 40 Ar/ 39 Ar ages on megacrystic kaersutite from four lamprophyre dikes, and a U-Pb zircon age on a trachyte, from central and north Westland (New Zealand) are presented. These ages suggest that the intrusion of mafic dikes (88-86 and 69 Ma) was not necessarily restr...

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Bibliographic Details
Published in:New Zealand journal of geology and geophysics 2013-12, Vol.56 (4), p.229-242
Main Authors: Van der Meer, QHA, Scott, JM, Waight, TE, Sudo, M, Scherstén, A, Cooper, AF, Spell, TL
Format: Article
Language:English
Subjects:
central Westland
Complex
Earth and Related Environmental Sciences
Fraser
Fraser Complex
geochronology
Geologi
Geological time
Geology
Geovetenskap och miljövetenskap
Gondwana break-up
lamprophyre
Magma
Natural Sciences
Naturvetenskap
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Summary:Newly determined Late Cretaceous 40 Ar/ 39 Ar ages on megacrystic kaersutite from four lamprophyre dikes, and a U-Pb zircon age on a trachyte, from central and north Westland (New Zealand) are presented. These ages suggest that the intrusion of mafic dikes (88-86 and 69 Ma) was not necessarily restricted to the previously established narrow age range of 80-92 Ma. The younger lamprophyre and trachyte dikes (c. 68-70 Ma) imply that tensional stresses in the Western Province were either renewed at this time, or that extension and related magmatism continued during opening of the Tasman Sea. Extension-related magmatism in the region not only preceded Tasman seafloor spreading initiation (starting at c. 83 Ma, lasting to c. 53 Ma), but may have sporadically continued for up to 15 Ma after continental break-up.
ISSN:0028-8306
1175-8791
DOI:10.1080/00288306.2013.826699