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Seth Burgess (2019)
Deciphering mass extinction triggers.
Science 363(6429): 815-816
DOI: 10.1126/science.aaw0473
Five mass extinction events have punctuated the evolution of life on Earth, each reshaping the biosphere by ending the success of an overwhelming proportion of species and creating ecological space for organisms that later inhabited the planet (1). Knowledge of the cause or causes of these events can inform understanding of how the biosphere responds to dramatic environmental change and can help to validate hypotheses about probable outcomes of anthropogenic changes. The nuanced interplay between the climate and ocean systems and the organisms that depend on them is preserved in the rock record for past mass extinctions. Reports by Sprain et al. (2) and Schoene et al. (3) on pages 866 and 862, respectively, of this issue focus on the cause of what is perhaps the most infamous of these mass extinctions, the K-Pg extinction, which marks the boundary between the Cretaceous and Paleogene periods on the geologic time scale.
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Blair Schoene, Michael P. Eddy, Kyle M. Samperton, C. Brenhin Keller, Gerta Keller, Thierry Adatte & Syed F. R. Khadri (2019)
U-Pb constraints on pulsed eruption of the Deccan Traps across the end-Cretaceous mass extinction.
Science 363(6429):Â 862-866
DOI: 10.1126/science.aau2422
Two timelines for extinction
The Cretaceous-Paleogene extinction that wiped out the nonavian dinosaurs 66 million years ago was correlated with two extreme events: The Chicxulub impact occurred at roughly the same time that massive amounts of lava were erupting from the Deccan Traps (see the Perspective by Burgess). Sprain et al. used argon-argon dating of the volcanic ash from the Deccan Traps to argue that a steady eruption of the flood basalts mostly occurred after the Chicxulub impact. Schoene et al. used uranium-lead dating of zircons from ash beds and concluded that four large magmatic pulses occurred during the flood basalt eruption, the first of which preceded the Chicxulub impact. Whatever the correct ordering of events, better constraints on the timing and rates of the eruption will help elucidate how volcanic gas influenced climate.
Abstract
Temporal correlation between some continental flood basalt eruptions and mass extinctions has been proposed to indicate causality, with eruptive volatile release driving environmental degradation and extinction. We tested this model for the Deccan Traps flood basalt province, which, along with the Chicxulub bolide impact, is implicated in the Cretaceous-Paleogene (K-Pg) extinction approximately 66 million years ago. We estimated Deccan eruption rates with uranium-lead (U-Pb) zircon geochronology and resolved four high-volume eruptive periods. According to this model, maximum eruption rates occurred before and after the K-Pg extinction, with one such pulse initiating tens of thousands of years prior to both the bolide impact and extinction. These findings support extinction models that incorporate both catastrophic events as drivers of environmental deterioration associated with the K-Pg extinction and its aftermath.
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Courtney J. Sprain, Paul R. Renne, LoÃc Vanderkluysen, Kanchan Pande, Stephen Self & Tushar Mittal (2019)
The eruptive tempo of Deccan volcanism in relation to the Cretaceous-Paleogene boundary.
Science 363(6429): 866-870
DOI: 10.1126/science.aav1446
Two timelines for extinction
The Cretaceous-Paleogene extinction that wiped out the nonavian dinosaurs 66 million years ago was correlated with two extreme events: The Chicxulub impact occurred at roughly the same time that massive amounts of lava were erupting from the Deccan Traps (see the Perspective by Burgess). Sprain et al. used argon-argon dating of the volcanic ash from the Deccan Traps to argue that a steady eruption of the flood basalts mostly occurred after the Chicxulub impact. Schoene et al. used uranium-lead dating of zircons from ash beds and concluded that four large magmatic pulses occurred during the flood basalt eruption, the first of which preceded the Chicxulub impact. Whatever the correct ordering of events, better constraints on the timing and rates of the eruption will help elucidate how volcanic gas influenced climate.
Abstract
Late Cretaceous records of environmental change suggest that Deccan Traps (DT) volcanism contributed to the Cretaceous-Paleogene boundary (KPB) ecosystem crisis. However, testing this hypothesis requires identification of the KPB in the DT. We constrain the location of the KPB with high-precision argon-40/argon-39 data to be coincident with changes in the magmatic plumbing system. We also found that the DT did not erupt in three discrete large pulses and that >90% of DT volume erupted in <1 million years, with ~75% emplaced post-KPB. Late Cretaceous records of climate change coincide temporally with the eruption of the smallest DT phases, suggesting that either the release of climate-modifying gases is not directly related to eruptive volume or DT volcanism was not the source of Late Cretaceous climate change.
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News:
The Real Dino Killer: A OneâTwo Punch
An asteroid impact and volcanoes acting together could have done in the beasts, new rock dates indicate
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Do volcanoes or an asteroid deserve blame for dinosaur extinction