An appraisal of the ages of Phanerozoic large igneous provinces

Abstract

Large igneous provinces (LIPs) are the products of exceptional magmatic events that played important roles in tectonic plate reorganizations, environmental crises, energy resource formation and ore genesis. Studying the ages of LIPs has been crucial for constraining the duration of these magmatic events and deciphering their temporal relationship with associated geological events. There have been a significant number of radio-isotopic dating analyses (e.g., 40Ar/39Ar, U-Pb) conducted for LIPs, especially in the past decade. These dating results have often been directly accepted and propagated into the literature for geological interpretations, regardless of their reliability and precision. This review compiles all published 40Ar/39Ar and U-Pb age determinations for the eighteen Phanerozoic large igneous provinces and critically evaluates each for their statistical robustness and precision. The compiled and filtered age data are easily accessible in an online database (https://shorturl.at/kIQT5) that will be regularly maintained by the authors. Using a filtered dataset of reliable and precise ages, which accounts for ∼30% of all the originally published ages, we discuss the duration of large igneous provinces and compare their relative timing with mass extinctions and global environmental crises. We find that the filtered datasets indeed provide robust evidence for a short duration of a few million years for some LIPs (i.e., Emeishan LIP, Siberian Traps, Central Atlantic magmatic province, Karoo LIP, Ferrar LIP, Paraná–Etendeka LIP, Deccan Traps, and Columbia River basalt group). However, evidence for the claimed short-lived, or long-lived and pulsed magmatism for some LIPs is insufficient (e.g., Yakutsk–Vilyui LIP, Kerguelen LIP, Caribbean LIP, High Arctic LIP, North Atlantic igneous province) and more robust geochronology data are needed to constrain their duration and tempo. The filtered data also strengthen the synchronicity between the peak magmatic phase of most LIPs and their associated environmental crises. Clear correlations are identified between the severity of environmental perturbations and LIPs' magma flux rates and likely their accompanied volatile degassing rates, indicating that LIP-induced rapid and intense volatile degassing may have been an important mechanism for a LIP to trigger the deterioration of the environment and even mass extinction.