New Zealand's Geological Foundations

We formally introduce 14 new high-level stratigraphic names to augment existing names and to hierarchically organise all of New Zealand's onland and offshore Cambrian–Holocene rocks and unconsolidated deposits. The two highest-level units are Austral Superprovince (new) and Zealandia Megasequence (new). These encompass all stratigraphic units of the country's Cambrian–Early Cretaceous basement rocks and Late Cretaceous–Holocene cover rocks and sediments, respectively. Most high-level constituents of the Austral Superprovince are in current and common usage: Eastern and Western Provinces consist of 12 tectonostratigraphic terranes, 10 igneous suites, 5 batholiths and Haast Schist. Ferrar, Tarpaulin and Jaquiery suites (new) have been added to existing plutonic suites to describe all known compositional variation in the Tuhua Intrusives. Zealandia Megasequence consists of five predominantly sedimentary, partly unconformity-bounded units and one igneous unit. Momotu and Haerenga supergroups (new) comprise lo...

https://www.tandfonline.com/doi/pdf/10.1080/00288306.2014.946062

High-level stratigraphic scheme for New Zealand rocks

https://www.earthbyte.org/Resources/Pdf/Matthews_105-100Ma_event_EPSL2012.pdf

A global-scale plate reorganization event at 105−100 Ma

Author Posting. © The Author, 2006. This is the author's version of the work. It is posted here by permission of Oxford University Press for personal use, not for redistribution. The definitive version was published in Journal of Petrology 27 (2006): 1673-1704, doi:10.1093/petrology/egl024.

/pdf/the-origin-of-himu-in-the-sw-pacific-evidence-from-1k783gazas.pdf

The Origin of HIMU in the SW Pacific: Evidence from Intraplate Volcanism in Southern New Zealand and Subantarctic Islands

Abstract We report new, highly precise, U–Pb and Ar/Ar ages for seven Cretaceous rhyolites, tuffs and granites from across Zealandia spanning a 30 Ma period from arc magmatism to continental break-up. Combined with previously published data, these reveal a strong episodicity in Cretaceous silicic magmatism outside the Median Batholith. 112 Ma tuffs are known only from the Eastern Province in association with a Cretaceous normal fault system. Both 101 and 97 Ma groups of rhyolites and tuffs occur across the entire width and half the length of Zealandia from near the palaeotrench to the continental interior, indicating widespread and effectively instantaneous extension. We attribute an increase in A-type character with time (112–101–97–88–82 Ma) to the progressive thinning of the Zealandia continental crust whereby, with time, there is less opportunity for crustal contamination. Extension directions associated with 101, 97 and 82 Ma magmatism and associated core complex exhumation across Zealandia are all oriented c. 30° oblique to the margin. These observations suggest Zealandia rifting was controlled by either >83 Ma capture of Zealandia by the Pacific Plate and/or <83 Ma Zealandia–West Antarctica spreading, rather than by laterally migrating triple junctions, slab windows or plume heads.

Cretaceous felsic volcanism in New Zealand and Lord Howe Rise (Zealandia) as a precursor to final Gondwana break-up

The Break-up of a Long-term Relationship: the Cretaceous Separation of New Zealand from Gondwana

The Taranaki Basin, situated offshore western New Zealand, is one of several large sedimentary basins formed during the Late Cretaceous in response to break-up of the palaeo-Pacific margin of Gondwana. A review of published structural, stratigraphic and geochronological data indicates that NE to NNE striking basement faults, generated during Palaeozoic to Mesozoic terrane accretion along the Gondwana margin, have strongly influenced the development of the basin. The main basin-bounding faults, the Cape Egmont Fault Zone and the Taranaki Fault, correspond to the boundaries of a narrow belt of plutonic rocks known as the Median Tectonic Zone. Geological data from onshore South Island suggests that right-lateral movement occurred along the boundaries of the Median Tectonic Zone during the Early Cretaceous. From the Late Cretaceous to Early Tertiary, NE to NNE striking normal faults within the Taranaki Basin controlled deposition in a series of en-echelon half-grabens and sub-basins. Many of the normal faults were later reactivated during a phase of compressional deformation associated with the development of the Australian-Pacific plate boundary through New Zealand. Reverse movement on the Taranaki Fault began in the early Miocene and deformation propagated westward reaching the Cape Egmont Fault Zone in the late Miocene to early Pliocene.

M. G. Laird

Papers

The Break-up of a Long-term Relationship: the Cretaceous Separation of New Zealand from Gondwana

The influence of basement structure on the evolution of the Taranaki Basin, New Zealand