Age and isotopic characterisation of metasedimentary rocks from the Torlesse Supergroup and Waipapa Group in the central North Island, New Zealand

Abstract

Sr ratios (at metamorphism) and detrital zircon patterns that in part are transitional between Rakaia and Pahau Terrane rocks and in part similar to Waipapa Terrane rocks. Combined detrital zircon age data for all Torlesse and Waipapa Terrane data reveal an essential unity, with a long persistence (260-120 Ma) of predominant Permian-Triassic sources in the form of a major Cordilleran-style batholith, a decline in major early Paleozoic-Precambrian sources between 260 and 220 Ma, and presence of minor Early Carboniferous to Late Devonian sources between 180 and 120 Ma. Rb-Sr and K-Ar ages indicate latest Triassic to Early Cretaceous metamorphism in an evolving accretionary wedge.

Tracing the Caples Terrane through New Zealand using detrital zircon age patterns and radiogenic isotope signatures

“…The former shows strong clustering of data close to the stratigraphic age limit (i.e., zircon sources mostly probably connected to contemporary magmatism) whilst the latter show a more equal division between that and inherited (mostly early Paleozoic and Precambrian) zircon components. Some detailed implications of these data, in particular with respect to the North island basement terranes, are discussed in Adams et al (2009). With particular reference to the South island terranes, the Caples Terrane data well illustrate the most distinctive feature of all eastern Province terrane dataseis (and particularly the accretionary terrane group), that of the prominent and enduring contribution, over 150 m.y., of Late Permian to Early Triassic zircon components.…”

“…11) and Puketona, Northland (fig. 9, and Adams et al 2007), and on Kapiti island, Wellington (Adams et al 2009). This supports the conclusion from Rb-Sr (t)-(i) data that Aspiring Terrane rocks (Norris & Craw 1987) (Pickard et al 2000;Wandres et al 2004b;Adams et al 2007).…”

“…14 detrital zircon 238U/206Pb age components (from this work and all previously published sources) derived from cumulative probability diagrams of greywackes in the Caples Terrane (from fig. 10), and adjacent accretionary Torlesse and Waipapa Terranes (from Adams et al 2009). The Caples Terrane samples are stacked from top to bottom in ascending maximum stratigraphic age order (as denoted by their youngest detrital zircon age components); in some cases small adjustments, ±2 ma, have been made to avoid overlap of important datasets.…”

Refined depositional history and dating of the Tongaporutuan reference section, north Taranaki, New Zealand: new volcanic ash U–Pb zircon ages, biostratigraphy and sedimentation rates

“…The initial zircon screening procedure used here allowed volcanic grains to be quickly differentiated from older detrital contaminants. The technique may be especially useful in studies of sediment provenance in New Zealand basins, given that differences in age between the basin-fill strata and volcanic ashes can be c. >100 Ma (Mortimer 2004;Adams et al 2009aAdams et al , 2009bMaier 2012).…”

From 2D to 3D: Prospectivity modelling in the Taupo Volcanic Zone, New Zealand

“…These remnants include Oligocene limestone and Lower Miocene volcaniclastic sandstone. Volcaniclastic sandstones of the Mesozoic Torlesse and Waipapa terranes comprise the TVZ basement (Adams et al, 2009) supplying heated fluids to the TVZ geothermal systems alongside inferred intrusive rocks (Rowland and Sibson, 2001). Activity ceased along the CVZ from 2 Ma, as the zone merged with the newly developing NNE-trending TVZ (Wilson et al, 1995).…”