Late Cretaceous and Paleocene terrestrial climates of New Zealand: Leaf fossil evidence from South Island assemblages

Abstract

Univariate and multivariate leaf morphologybased analysis of leaf fossil assemblages from localities in the South Island of New Zealand provide quantitative paleoclimate estimates for the terrestrial Late Cretaceous and Paleocene. Favourable growing conditions with a cool to mild temperate climate are inferred for the youngest pollen zone in the Late Cretaceous (PM2) with moderately high precipitation and high dicotyledonous angiosperm diversity. Mean annual temperature estimates of c. 12-16 and c. 7-11°C were produced from northwest Nelson and North Otago PM2 Zone assemblages, respectively. These different temperature estimates most likely reflect differences in age, although geographic differences may also be a factor. Consistent data from three Paleocene assemblages suggest cool-temperate conditions. Mean annual temperature estimates of c. 6-12°C were produced from these Paleocene assemblages. They also had lower dicotyledonous leaf diversity than the Late Cretaceous assemblages, no more than 30 different angiosperm leaf forms.

The Cretaceous/Tertiary boundary event in New Zealand: Profiling mass extinction

“…When related to the Clarence valley records, these inferred climate cycles are shown to be linked to sea-level changes (Hollis et al 2003a). When linked to evidence for significant relative sea-level changes (Moore 1989;McMillan & Wilson 1997;Laird et al 2003) and cool climatic conditions (Vajda et al 2001;Kennedy 2003;Vajda & Raine 2003) during the early Paleocene throughout New Zealand, a case can be made along the lines proposed by D 'Hondt et al (1996a). Namely, mass extinction of calcareous plankton, resulting in greatly reduced CO 2 drawdown, coupled with injection into the atmosphere of massive quantities of CO 2 following vaporisation of carbonate target rock (O'Keefe & Ahrens 1989;Pope et al 1997), caused long-term disruption to the biogeochemical feedback systems that influence climate.…”

“…Cool climatic conditions for the early Paleocene are also inferred from low-resolution studies of Antarctic plant fossils and sediments (Francis 1991;Askin 1992;Dingle & Lavelle 1998) and New Zealand fossil leaf physiognomy (Kennedy 2003). The terrestrial palynomorph record at mid Waipara (Vajda & Raine 2003) indicates that cool climatic conditions began within Foraminiferal Zone Pa and persisted into upper Radiolarian Zone RP3, that is, a duration equivalent to the inferred cool climate period in Marlborough.…”

“…Occurrences of slumps, olistostromes, and crossbedding in uppermost Cretaceous strata atTora, southeastern Wairarapa, indicate that local tectonic activity and uplift occurred in some areas . Physiognomic analysis of leaf assemblages (Kennedy 2003) and general features of terrestrial palynomorph (Vajda & Raine 2003), planktic foraminiferal, and radiolarian assemblages (Hollis et al 2003b) indicate cool to mild temperate oceanic and climatic conditions, with moderately high precipitation, for latest Cretaceous (Haumurian) New Zealand. Weak cyclic variation in clay content in uppermost Cretaceous strata in Marlborough may reflect climatic cycles, possibly with Milankovitch-scale periodicity .…”

The Miocene climate in New Zealand: Estimates from paleobotanical data

“…To remain 'everwet', annual rainfall would only need to be about 400 mm. Kennedy (2003) reported results from Late Cretaceous-Paleocene assemblages said to contain up to 58 dicotyledonous taxa -but the justification for the extraordinary number of taxa remains unpublished. My impression is that perhaps 5-8 taxa are able to be distinguished in the richest assemblage.…”

An outcrop‐based study of the economically significant Late Cretaceous Rakopi Formation, northwest Nelson, Taranaki Basin, New Zealand

“…The interpretations of depositional setting have largely been based on seismic facies mapping (Thrasher & Cahill 1990;Thrasher 1992), pollen and spore studies (Raine 1984(Raine , 1989(Raine , 1992a(Raine ,b, 1994Crouch 2002), plant macrofossil studies (Mildenhall 1968;Kennedy 1993Kennedy , 1998Kennedy , 2003Kennedy et al 2002), and electric log character (King & Thrasher 1996). Previous workers have regarded the formation as floodplain deposits dominated by meandering stream and overbank environments (Titheridge 1977;Thrasher 1991aThrasher , 1992Wizevich 1994;King & Thrasher 1996).…”