A younger and protracted emplacement of the Ontong Java Plateau

Abstract

The submarine volcanic emplacement of the Ontong Java Plateau (OJP) is the suggested cause of Ocean Anoxic Event 1a (OAE 1a). However, no precise timing and duration exists for the formation of OJP, and its connection to OAE1a relies mainly on proxies in the sedimentary record. We provide high-precision 40 Ar/ 39 Ar data from OJP drill and dredge sites that considerably improve OJP’s eruptive history. The ages determined from this work are as much as 10 million years younger than previous dates and indicate a protracted formation over at least 6 million years. OJP now appears too young to have caused OAE1a, but we suggest that it may have had a role in the later OAE1b. The protracted eruptive sequence has implications for the emplacement dynamics of OJP and other large igneous provinces.

Causes of Late Cretaceous subduction termination below South China and Borneo: Was the Proto-South China Sea underlain by an oceanic plateau?

“…Alternatively, the different ages may be related to a main event of oceanic plateau formation in the latest Jurassic, with secondary volcanism after the main stage of plateau formation. The Ontong Java Plateau, for example, had a main stage of formation at around 117-118 Ma, but later-stage magmatism also occurred from ~111-108 Ma and at c. 90 Ma (Mahoney et al, 1993;Fitton et al, 2004;Korenaga, 2005;Davidson et al, 2023). The c. 20 Ma age difference in the Pontus Plate volcanoes is therefore not unusual.…”

Heterogeneous Crustal Structure of the Hikurangi Plateau Revealed by SHIRE Seismic Data: Origin and Implications for Plate Boundary Tectonics

“…The Hikurangi Plateau is subducting along New Zealand's Hikurangi margin at a rate of ∼20–60 mm/year (Figure 1) (Mortimer & Parkinson, 1996; Reyners et al., 2011; Wallace et al., 2004). The Plateau is thought to have formed between ∼96 and 118 Ma as part of a larger Hikurangi‐Manihiki‐Ontong Java Plateau, which would represent the largest magmatic event preserved at Earth's surface (Coffin & Eldholm, 1994; Davidson et al., 2023; Hoernle et al., 2010; Taylor, 2006; Tejada et al., 2023; Timm et al., 2011). Rifting, followed by seafloor spreading at the Osbourn Trough separated the Hikurangi and Manihiki Plateaus, with the Hikurangi Plateau drifting south before its collision and incipient subduction at the Gondwana margin, which has been linked to the cessation of subduction in this region (Billen & Stock, 2000; Davy et al., 2008a; Hoernle et al., 2020; Lonsdale, 1997; Riefstahl et al., 2020; Wood & Davy, 1994).…”