Continental-scale geographic change across Zealandia during Paleogene subduction initiation

Rupert Sutherland ,A Bordenave,G Asatryan,A.L Keller,K.M Pascher,Cherry Newsam ,Adriane R Lam ,Huai-Hsuan May Huang ,Thomas Westerhold ,Margot J Cramwinckel ,H Li ,Stephen F Pekar ,Joyeeta Bhattacharya ,Michael Gurnis ,Peter Blum ,Hiroki Matsui ,Donald E Penman ,Laia Alegret ,W Stratford ,Martino Giorgioni ,Julien Collot ,Hugh E G Morgans ,Liao Chang ,Edoardo Dallanave ,Dustin T Harper ,Claudia Agnini ,M K Drake ,Gerald R Dickens ,Saneatsu Saito ,Samuel Étienne ,Park Yh ,Xiwen Zhou

doi:10.1130/g47008.1

Abstract

Abstract Data from International Ocean Discovery Program (IODP) Expedition 371 reveal vertical movements of 1–3 km in northern Zealandia during early Cenozoic subduction initiation in the western Pacific Ocean. Lord Howe Rise rose from deep (∼1 km) water to sea level and subsided back, with peak uplift at 50 Ma in the north and between 41 and 32 Ma in the south. The New Caledonia Trough subsided 2–3 km between 55 and 45 Ma. We suggest these elevation changes resulted from crust delamination and mantle flow that led to slab formation. We propose a “subduction resurrection” model in which (1) a subduction rupture event activated lithospheric-scale faults across a broad region during less than ∼5 m.y., and (2) tectonic forces evolved over a further 4–8 m.y. as subducted slabs grew in size and drove plate-motion change. Such a subduction rupture event may have involved nucleation and lateral propagation of slip-weakening rupture along an interconnected set of preexisting weaknesses adjacent to density anomalies.

Highlights

Major global plate-motion change occurred between 52 and 43 Ma, as manifested by the Emperor-Hawaii bend (Steinberger et al, 2004; O’Connor et al, 2013), reorientation of midocean ridges (Muller et al, 2000; Steinberger et al, 2004; Cande et al, 2010), and rifting of Antarctica (Cande et al, 2000)
We discuss the evidence collected and reasons for topographic change, and we propose a new framework for understanding subduction initiation
We discovered Paleogene fossils indicative of nearby neritic conditions at sites far below sea level (Fig. DR3)

Summary

INTRODUCTION

Major global plate-motion change occurred between 52 and 43 Ma, as manifested by the Emperor-Hawaii bend (Steinberger et al, 2004; O’Connor et al, 2013), reorientation of midocean ridges (Muller et al, 2000; Steinberger et al, 2004; Cande et al, 2010), and rifting of Antarctica (Cande et al, 2000) This coincided with subduction initiation (Fig. 1) in the IzuBonin-Mariana (IBM) system (Arculus et al, 2015; Reagan et al, 2017), and nascent collision of the Indian and Asian plates (Aitchison et al, 2007).

Marine continental slopes

Tonga forearc

Lord Howe Rise

Buoyant rising of blueschist