Change from calc‐alkaline to adakitic magmatism recorded in the Early Cretaceous Darran Complex, Fiordland, New Zealand
| Autor: | David Shelley, Anekant M Wandres, John D. Bradshaw, Steve Weaver |
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| Rok vydání: | 1998 |
| Předmět: | |
| Zdroj: | New Zealand Journal of Geology and Geophysics. 41:1-14 |
| ISSN: | 1175-8791 0028-8306 |
| DOI: | 10.1080/00288306.1998.9514786 |
| Popis: | The Early Cretaceous Darran Complex of the Median Tectonic Zone near Milford, South Island, New Zealand, consists dominantly of biotite ‐ two‐pyroxene diorites cut by biotite‐hornblende microdiorite and quartz monzodiorite dikes. The host diorite gives a 138 ± 2.9 Ma SHRIMP age on zircons, which is interpreted to be the age of igneous crystallisation. The calc‐alkaline geochemistry of the host diorites and the microdiorites is attributed to melting of a mantle wedge source fluxed by slab‐derived fluids. Ductile deformation (D1) of the host diorite and the microdiorite dikes took place at mid‐upper amphibolite facies conditions, with extension lineations indicating a top to the NNE sense of shear. A SHRIMP age of 136 ± 1.9 Ma on zircons from a quartz monzodiorite dike injected along D1 shears is statistically indistinguishable from that of the host diorite. This suggests that D1 was synmagmatic and that subduction, during or shortly after magma emplacement, was oblique to the Gondwana margin at c.... |
| Databáze: | OpenAIRE |
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