The mid-Cretaceous transition from basement to cover within sedimentary rocks in eastern New Zealand: evidence from detrital zircon age patterns

Abstract

Detrital zircon U-Pb ages for 30 Late Jurassic and Cretaceous sandstones from the Eastern Province of eastern New Zealand, combined with previously-published geochronological and palaeontological data, constrain the time of deposition in the Pahau and Waioeka terranes of the Cretaceous accretionary margin of Zealandia, and their adjacent cover strata. The zircon age patterns also constrain possible sediment source areas and mid-Cretaceous geodynamic models of the transition from basement accretionary wedge to passive-margin cover successions. Pahau Terrane deposition was mainly Barremian to Aptian but continued locally through to late Albian time, with major source areas in the adjacent Kaweka and Waipapa terranes and minor inputs from the inboard Median Batholith. Waioeka Terrane deposition was mainly Albian, with distinctive and exclusive sediment sources, principally from the Median Batholith but with minor inputs from the Western Province. Alternative tectonic models to deliver such exclusive Median Batholith and Western Province-derived sediment to the mid-Cretaceous Zealandia continental margin are: (1) the creation of a rift depression across Zealandia or (2) sinistral displacement of South Zealandia with respect to North Zealandia, to expose Western Province rocks directly at the Zealandia margin. Detrital zircon age patterns of Cretaceous cover successions of the Eastern Province of eastern New Zealand demonstrate purely local sources in the adjacent Kaweka and Waipapa terranes. Cretaceous zircon components show a decline in successions of late Early Cretaceous age and disappear by late Late Cretaceous time, suggesting the abandonment or loss of access to both the Median Batholith and Western Province as sediment sources.

Paleozoic evolution of western Marie Byrd Land, Antarctica

“…The Neoproterozoic-Cambrian population of zircons from the Swanson Formation contains more evolved ε Hf(t) values than the Mesoprotero zoic population, which is consistent with derivation from igneous and metamorphic rocks associated with crustal reworking in the Ross-Delamerian orogen Adams et al, 2013). In the Central Transantarctic Mountains, the oldest intrusive rocks are dated at ca.…”

“…It is a folded and cleaved metaturbidite sequence that accumulated outboard of the Cambrian Ross-Delamerian orogen. In a regional context, based on the similarity of U-Pb ages of detrital zircons, the Swanson Formation has been correlated with the Robertson Bay Group in north Victoria Land and the Greenland Group in the Western Province of New Zealand Adams et al, 2013). Paleocurrent data from the Swanson Formation have been interpreted to suggest fl ow predominantly toward the north (Bradshaw et al, 1983), indicating a source terrain to the south.…”

“…2) from Adams et al (2013), are plotted as histograms and normalized probability distributions in Figures 3A-3F. In addition, the ages of inherited grains (interpreted as >400 Ma) in the Ford Granodiorite suite, the Devonian-Carboniferous granites, and the diatexites are plotted in Figure 3G.…”

Cretaceous sedimentation and metamorphism of the western Alpine Schist protoliths associated with the Pounamu Ultramafic Belt, Westland, New Zealand

“…Other Pahau sandstones of Cretaceous or probable Cretaceous ages from Marlborough and Wairarapa yielded 114Á129 Ma and 136Á177 Ma populations that comprised 12% and 7% of the samples, respectively (Pickard et al 2000). In north Canterbury, Adams et al (2013b) determined a minimum detrital zircon age population of 10491 Ma in basement Pahau terrane greywacke. Cretaceous detrital zircon ages have also been reported in the North Island greywacke sequences from the Morrinsville facies of the Waipapa terrane and from the Omaio facies of the Torlesse (Cawood et al 1999).…”

“…In the Omaio facies, 50% of zircons have ages between 99 and 133 Ma, while in the Morrinsville facies populations range from c. 141 to 166 Ma. The youngest detrital zircon populations determined by Adams et al (2013b) in Omaio facies rocks range from 10092 to 11291 Ma. These basement ages overlap with a UÁPb age of 101.690.2 Ma from tuff bed T2 in the unconformably overlying Karekare Formation cover sequence at Motu Falls, Raukumara Peninsula (Crampton et al 2004).…”