Late Cretaceous (99-69 Ma) basaltic intraplate volcanism on and around Zealandia: Tracing upper mantle geodynamics from Hikurangi Plateau collision to Gondwana breakup and beyond

Abstract

Collision of a young, buoyant plateau fragment with an active continental margin can lead to subduction cessation, but can it also trigger continental breakup? It has been postulated that the collision of the Hikurangi Plateau with the Gondwana margin at ~110 Ma ago, caused subduction to cease, large-scale extension and ultimately breakoff of the Zealandia microcontinent from West Antarctica through seafloor spreading starting at circa 90 Ma. Here we report new geochemical (major and trace element and Sr-Nd-Pb-Hf isotope) data for Late Cretaceous (99-69Ma) volcanism from Zealandia. Four geographically-separated provinces of intraplate magmatism formed during this time interval: 1) Hikurangi Seamount Province *Manuscript Click here to view linked References

Extent and Cessation of the Mid‐Cretaceous Hikurangi Plateau Underthrusting: Impact on Global Plate Tectonics and the Submarine Chatham Rise

“…Slab tearing created a pathway for mantle upwelling, which affected the evolving southern Zealandia rifted margin around 85 Ma (Hoernle et al, 2020; Riefstahl et al, 2020; Tulloch et al, 2019). Alkaline magmatism occurred on the Chatham Islands between 86 and 79 Ma (Panter et al, 2006) and at several seamounts further to the south and west of the Chatham Islands (Hoernle et al, 2020; Homrighausen et al, 2018; Mortimer, Campbell, & Moerhuis, 2019).…”

“…Alkaline magmatism occurred on the Chatham Islands between 86 and 79 Ma (Panter et al, 2006) and at several seamounts further to the south and west of the Chatham Islands (Hoernle et al, 2020; Homrighausen et al, 2018; Mortimer, Campbell, & Moerhuis, 2019). Isotopic constraints of this intraplate volcanic event indicate a common HIMU end‐member across multiple volcanic provinces in southern Zealandia (Hoernle et al, 2020) and suggest that the same deep‐mantle source was involved in the evolution of the alkaline volcanic provinces located on the South Islands Marlborough (98–69 Ma; McCoy‐West et al, 2010; Mortimer, Campbell, & Moerhuis, 2019; van der Meer et al, 2016, 2017) and seamounts on the Hikurangi Plateau (99–86 Ma; Hoernle et al, 2010). If the mantle was already upwelling beneath the Hikurangi Plateau and the Phoenix Plate at or before 100 Ma, this could have also contributed to shallow subduction and flattening of the Phoenix Plate slab before 100 Ma (Figure 8b).…”

“…Slab tearing created a pathway for mantle upwelling, which affected the evolving southern Zealandia rifted margin around 85 Ma (Hoernle et al, 2020;Riefstahl et al, 2020;Tulloch et al, 2019). Alkaline magmatism occurred on the Chatham Islands between 86 and 79 Ma (Panter et al, 2006) and at several seamounts further to the south and west of the Chatham Islands (Hoernle et al, 2020;Homrighausen et al, 2018;Mortimer, Campbell, & Moerhuis, 2019). Isotopic constraints of this intraplate volcanic event indicate a common HIMU end-member across multiple volcanic provinces in southern Zealandia (Hoernle et al, 2020) and suggest that the same deep-mantle source was involved in the evolution of the alkaline volcanic provinces located on the South Islands Marlborough (98-69 Ma; McCoy-West et al, 2010; Mortimer, 10.1029/2020JB019681 Campbell, & Moerhuis, 2019;van der Meer et al, 2016van der Meer et al, , 2017 and seamounts on the Hikurangi Plateau (99-86 Ma; Hoernle et al, 2010).…”

Introduction to volcanism in Antarctica: 200 million years of subduction, rifting and continental break-up

“…Over a period of a few million years in the Cretaceous, Antarctica's magmatism shifted from arc-related to rift-related during the latest stage of Gondwana break-up that separated Zealandia from Antarctica (c. 90-83 Ma). Rare Late Cretaceous alkaline intraplate magmatism is found in southern Zealandia (Weaver and Smith 1989), including HIMU-like ocean island basalt (OIB) (Panter et al 2006;Hoernle et al 2020), and mafic dykes are present along the Ruppert and Hobbs coasts of Marie Byrd Land (Storey et al 1999). However, the episode was largely amagmatic.…”

Magmatism in Antarctica and its relation to Zealandia

“…McDonough et al 1985;LeMasurier and Rex, 1989;Kyle et al 1992;Lanyon et al 1993;Baker et al 1994;Weaver et al 1994). Mantle plumes have been proposed as one cause of Late Cretaceous volcanism in New Zealand (Hoernle et al 2020) and some Late Cenozoic to on-going volcanic activity in West Antarctica (Hole and LeMasurier 1994;Phillips et al 2018). The presence of a large mantle plume may explain the distribution and origin of the Marie Byrd Land volcanoes (LeMasurier & Landis 1996).…”