Radiometric Constraints on the Timing, Tempo, and Effects of Large Igneous Province Emplacement

Abstract

There is an apparent temporal correlation between large igneous province (LIP) emplacement and global environmental crises, including mass extinctions. Advances in the precision and accuracy of geochronology in the past decade have significantly improved estimates of the timing and duration of LIP emplacement, mass extinction events, and global climate perturbations, and in general have supported a temporal link between them. In this chapter, we review available geochronology of LIPs and of global extinction or climate events. We begin with an overview of the methodological advances permitting improved precision and accuracy in LIP geochronology. We then review the characteristics and geochronology of 12 LIP/event couplets from the past 700 Ma of Earth history, comparing the relative timing of magmatism and global change, and assessing the chronologic support for LIPs playing a causal role in Earth's climatic and biotic crises. We find that (1) improved geochronology in the last decade has shown that nearly all well-dated LIPs erupted in < 1 Ma, irrespective of tectonic setting; (2) for well-dated LIPs with correspondingly well-dated mass extinctions, the LIPs began several hundred ka prior to a relatively short duration extinction event; and (3) for LIPs with a convincing temporal connection to mass extinctions, there seems to be no single characteristic that makes a LIP deadly. Despite much progress, higher precision geochronology of both eruptive and intrusive LIP events and better chronologies from extinction and climate proxy records will be required to further understand how these catastrophic volcanic events have changed the course of our planet's surface evolution.

An evaluation of Deccan Traps eruption rates using geochronologic data

“…To better compare the eruption rates from the two datasets, we have applied the same plotting strategy from Schoene et al (2019) to both the U−Pb and 40 Ar/ 39 Ar datasets. This approach assigns each sample to a position within a composite stratigraphic section plotted as cumulative volume and uses a Bayesian Markov Chain Monte Carlo (MCMC) algorithm to build an age model (Keller, 2018). Here, we use the assigned stratigraphic positions of the basalt samples from Fig.…”

Emplacement of the Franklin large igneous province and initiation of the Sturtian Snowball Earth

“…The Snowball Earth episodes are the most extreme climate changes in Earth's history, and, yet, the triggers for their initiation remain unclear and debated. Studies of the emplacement of large igneous provinces (LIPs) have demonstrated correlations with environmental perturbations (2,3), and geochronological constraints on the older of the two episodes, the Sturtian Snowball Earth, have highlighted a possible correlation in timing of onset with the emplacement of the Franklin LIP [e.g., (4,5)].…”

“…In the past several years, geochronology studies have constrained the duration and tempo of LIP emplacement, showing that >75% of total volume is emplaced in pulses of <5 Ma, with almost all highprecision studies showing emplacement in <1 Ma (3,15). On the basis of the established rates for LIP emplacement, the actual duration of emplacement for the Franklin LIP could be only a small portion of the current range in dates, highlighting the need for higher precision and accuracy in dating.…”

A red bole zircon record of cryptic silicic volcanism in the Deccan Traps, India

“…In particular, the potential for silicic magmas to play an outsized role in driving environmental degradation during LIP emplacement is underappreciated. Because these magmas can release volatiles that reach the upper atmosphere during explosive eruptions (Robock, 2000), knowledge of the frequency and volumes of silicic volcanism is needed for a complete understanding of the relationship between LIP emplacement and mass extinctions (Courtillot and Renne, 2003;Kasbohm et al, 2021).…”