Cretaceous termination of subduction at the Zealandia margin of Gondwana: The view from the paleo-trench

Evolution of a Normal Fault System Along Eastern Gondwana, New Zealand

“…These strata are considered to be prerift sedimentary rocks formed in association with arc volcanism (Tulloch et al, 2019). However, due to poor exposure of these outcrops and lack of seismic data in this region, the timing of deposition of these outcrop strata relative to the onset of faulting remains unclear and, consistent with previous publications (Crampton et al, 2019;Laird, 1993;Sutherland et al, 2001), we adopt~105 Ma as the onset of faulting (here inferred to be equivalent to the top basement horizon). The ages of the K40, K65, K80, K90, P00, and P10 horizons adopted in this publication were estimated by correlation to offshore wells (e.g., Kawau-1A, Hoiho-1C, Pukaki-1, Pakaha-1, Rakiura-1, Tara-1, Toroa-1, Galleon-1, Cutter-1, Endeavour-1, Clipper-1, and Caravel-1).…”

A Forearc Stratigraphic Response to Cretaceous Plateau Collision and Slab Detachment, South Island, New Zealand

“…Clastic units were deposited within a largely marine forearc setting along the New Zealand continental margin segment of East Gondwana, and preserve evidence of disrupted deposition between 108 and 95 Ma (Gardiner & Hall, 2021). Collision of the Hikurangi Plateau, a rifted fragment of the Ontong‐Java Nui large igneous province (Hochmuth et al., 2015; Hoernle et al., 2010; Taylor, 2006), from 110 Ma is commonly cited as the catalyst for subduction shut‐down (Crampton et al., 2019; Davy et al., 2008; Mortimer et al., 2019; Riefstahl et al., 2020). However, the timing and implications of plateau collision remain poorly constrained and competing accounts invoke ridge subduction prior to collision that is estimated or inferred as late as 71 Ma (Billen & Stock, 2000; Downey et al., 2007; Seton et al., 2012; Worthington et al., 2006).…”

“…The end of East Gondwanan subduction was an event of global significance, forming the final phase of a global plate reorganization that commenced at 111 Ma, following slab breakoff and subduction shut‐down in the Mesotethys Ocean (Matthews et al., 2012; Müller et al., 2016; Olierook et al., 2020; Schellart et al., 2006; Veevers, 2000; Zundel et al., 2019). Uncertainty remains, however, regarding the timing and manner of East Gondwanan subduction shut‐down (and collision of the Hikurangi Plateau) with estimates ranging between 100 and 86 Ma based variously on mapping of sea‐floor fabrics, stratigraphy, plate reconstructions, and geochronology (Barrett et al., 2018; Billen & Stock, 2000; Crampton et al., 2019; Davy, 2014; Kamp, 1999, 2000; Mazengarb & Harris, 1994; Mortimer et al., 2019; Müller et al., 2016). A sharp decline in the number of detrital zircons with inferred syn‐depositional magmatic ages of ∼100 Ma (Figure 3c) has been interpreted to reflect the cessation of arc magmatism and is often cited as a proxy for subduction shut‐down, although a small number of younger zircons suggest arc magmatism as late as 95 Ma (Adams et al., 2016, supplementary data).…”

“…Mildly deformed mid‐Cretaceous clastic and volcanic cover successions overlie Pahau Terrane (subduction wedge) units with variable thickness. The earliest confirmed cover units in the area are Albian, or New Zealand Urutawan (108.4‐103.3 Ma), located within the north‐eastern Clarence Valley (Crampton et al., 2019). Cover in the southwest of the Awatere Valley around Middlehurst Station (Figure 4a) consists of almost 2 km of Urutawan‐Motuan fluvio‐deltaic sedimentary rocks that are truncated by a c. 100 Ma subaerial unconformity, which is overlain by thin fluvial units and over 1 km of mildly alkaline basalt flows dated from 97.6 ± 3.2 to 90.3 ± 1.6 Ma (Challis & Wellman, 1966; McCoy‐West et al., 2010).…”

K-Ar fault-gouge dating in the Lower Buller gorge constrains the formation of the Paparoa Trough, West Coast, New Zealand

“…The terranes were assembled in the Jurassic and Early Cretaceous on the paleo-Pacific margin of Gondwana (Mortimer 2004;Mortimer et al 2017). Shortly after accretion, Zealandia began to extend and core complexes and various graben systems formed (Bradshaw 1989;Laird and Bradshaw 2004;Crampton et al 2019). On the West Coast of the South Island, the various extension events and associated basin formation phases are variably preserved in rock exposures and through stratigraphic and structural relationships.…”