Title:
Catastrophic Trigger That Led to Earth's Largest Mass Extinction Revealed in Fossils
Author:
David Nield
Published:
Science Alert, 21 October 2020
From the article:
Scientists think they've finally come closer to identifying the cause of Earth's worst mass extinction, by tracking down the geochemical trigger that may have started it all. Known as the Great Dying, the Permian-Triassic extinction event happened around 252 million years ago. The new research is based on a study of fossil shells left behind by clam-like brachiopods in what today is the Southern Alps.
Note from blog owner:
The research was published in a scholarly publication.
Title:
Permian–Triassic mass extinction pulses driven by major marine carbon cycle perturbations
Authors:
Hana Jurikova, Marcus Gutjahr, Klaus Wallmann, Sascha Flögel, Volker Liebetrau, Renato Posenato, Lucia Angiolini, Claudio Garbelli, Uwe Brand, Michael Wiedenbeck & Anton Eisenhauer
Published:
Nature Geoscience, 19 October 2020
Abstract:
The Permian/Triassic boundary approximately 251.9 million years ago marked the most severe environmental crisis identified in the geological record, which dictated the onwards course for the evolution of life. Magmatism from Siberian Traps is thought to have played an important role, but the causational trigger and its feedbacks are yet to be fully understood. Here we present a new boron-isotope-derived seawater pH record from fossil brachiopod shells deposited on the Tethys shelf that demonstrates a substantial decline in seawater pH coeval with the onset of the mass extinction in the latest Permian. Combined with carbon isotope data, our results are integrated in a geochemical model that resolves the carbon cycle dynamics as well as the ocean redox conditions and nitrogen isotope turnover. We find that the initial ocean acidification was intimately linked to a large pulse of carbon degassing from the Siberian sill intrusions. We unravel the consequences of the greenhouse effect on the marine environment, and show how elevated sea surface temperatures, export production and nutrient input driven by increased rates of chemical weathering gave rise to widespread deoxygenation and sporadic sulfide poisoning of the oceans in the earliest Triassic. Our findings enable us to assemble a consistent biogeochemical reconstruction of the mechanisms that resulted in the largest Phanerozoic mass extinction.