A 251 ma diorite clast from a maitai group conglomerate and a c. 259 ma microdiorite sill intruding the productus creek group, Southland, New Zealand: Note

N. Mortimer*, R. E. Turnbull, A. H.F. Robertson, H. J. Campbell

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract / Description of output

We present the results of U–Pb dating of zircons of two Late Permian igneous rocks from the Dun Mountain–Maitai and Brook Street terranes of New Zealand’s South Island. A conglomerate clast of hornblende diorite from the Early–Middle Triassic Stephens Subgroup, Maitai Group, gives an age of 251.1 ± 1.6 Ma. A sample of hypabyssal andesite–microdiorite (Weetwood Formation) that intrudes the Late Permian Productus Creek Group of the Brook Street Terrane gives an age of 258.8 ± 7.9 Ma. The intermediate and subalkaline geochemistry of the two samples is not distinctive of specific tectonic settings, but their ages match plutons of the I-type, subduction-related Longwood Suite of the nearby Median Batholith. Assuming that correlation with the Longwood Suite is correct, the Weetwood sample increases the known areal extent of intrusion of the Longwood Suite; and the Stephens Subgroup Formation clast is consistent with a detrital link between Gondwana and the Dun Mountain–Maitai Terrane by the Middle Triassic. However, because of uncertainties regarding the timing of magmatism along other parts of the Gondwana margin, the data in this paper do not establish any specific provenance links

Original languageEnglish
Title of host publicationGeological Society Memoir
PublisherGeological Society of London
Chapter12
Pages287-292
Number of pages6
Edition1
DOIs
Publication statusPublished - 1 May 2019

Publication series

NameGeological Society Memoir
Number1
Volume49
ISSN (Print)0435-4052

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