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Volcanism, Impacts and Mass Extinctions: Causes and Effects
Natural HIstory Museum, London
27-29 March 2013
The Natural History Museum in London recently hosted an international, multi-disciplinary conference that brought together 150 researchers in geology, geophysics, geochemistry, volcanology, sedimentology, paleontology and astronomy to review and assess recent research into the causes of mass extinction events. Participants included seasoned experts as well as younger researchers and students. Through listening and learning from each other and by spirited, constructive discussions, a new, collaborative and multi-disciplinary approach to resolving outstanding problems in this field was explored. The data and concepts presented and discussed at the meeting also have value well beyond the geosciences, particularly with regard to understanding modern environmental crises.
The main conclusions of the conference were:
1) Large igneous province volcanism, along with associated climate and environmental changes, is likely to have played a significant role in at least four of the five major mass extinctions in earth history: the end-Cretaceous, end-Triassic, end-Permian (comprising two distinct extinction events) and end-Devonian. However, the exact causal mechanisms by which 50-90% of the species preserved in the fossil record went extinct at each event remains to be worked out. Better age control for individual lava units and extinction events is critical to establish the relationship between the causes and effects.
2) There was overwhelming agreement that a single large asteroid or comet impact (Chicxulub) could not have been the sole cause of the end-Cretaceous mass extinction, but rather was a contributing factor. The long-term biological, environmental and climatic changes before, at and after the bolide impact horizon call for a multi-causal scenario, certainly involving volcanism and possibly multiple impacts or comet showers.
3) Participants gained an improved understanding of how large igneous province eruptions affect the biosphere. This included data and conclusions derived from atmospheric chemistry, geochronology of eruptions, associated mechanisms of climatic changes and the direct effects on species-level extinctions.
4) Mass extinction patterns can tell us much about the age, tempo and nature of the catastrophe and the type of environments that were most affected. We know most about the end-Cretaceous mass extinction. However, similarly detailed records are still needed for the other mass extinctions. If common patterns, or critical differences, between all mass extinctions are found these can yield critical evidence for or against specific extinction mechanisms.
5) Ultimately, the effects of volcanism, impacts, sea-level and climate changes (warming and cooling), ocean acidification, ocean anoxia and atmospheric changes have to be considered in any extinction scenario in order to understand the causes and consequences of mass extinctions. Moreover, these data hold keys to help us understand, and cope with, the looming environmental and extinction crises in the modern world.
A planned GSA Special Paper will serve not only as a lasting record of the meeting, but will also act as important guide for the multi-disciplinary studies still needed to resolve the outstanding problems in understanding the causes and effects of mass extinctions. See also Keller et al. (2013): http://www.geolsoc.org.uk/Geoscientist/Archive/November-2012/Volcanism-impacts-and-mass-extinctions-2
Podcast interview conducted by Sarah Day of the Geological Society with Gerta Keller, Andrew Kerr, Thierry Adatte and Anja Schmidt available here: https://www.geolsoc.org.uk/Education-and-Careers/Podcasts/Volcanism-impacts-and-mass-extinction
Acknowledgements: The conference was supported by The Natural History Museum (London), the Mineralogical Society of Great Britain and Ireland, the Volcanic and Magmatic Studies Group of the UK, the Solid Earth Composition and Evolution Working Group of the IMA, the Society of Sedimentary Geology, the Earth Science Institute, Lausanne University, Switzerland, and the Department of Geosciences, Princeton University.
Photos courtesy of the Natural History Museum