Permian extinction amplified by plume induced release of recycled lithospheric volatiles
Authors: Michael Broadley, Peter Barry, Chris Ballentine, Larry Taylor, Ray Burgess
Journal: Nature Geoscience
Publication Date: 27 August, 2018
School of: Earth and Environmental Sciences
Volatile Siberian trap eruptions deplete global ozone layer
Researchers at the University of Manchester have discovered that destruction of the ozone layer was one of the root causes of the end-Permian extinction, the Earth’s most severe mass extinction event which killed off 90 percent of marine organisms and 70 percent of life on land. The extinction coincided with emplacement of the Siberian Traps, a large igneous province formed from accumulations of lavas and sub-surface intrusions. Halogen compositions of lithospheric mantle xenoliths emplaced before and after eruption of the Siberian Traps showed the Siberian lithosphere was massively enriched in halogens from the infiltration of subducted seawater, but levels were much lower after the extinction event. The halogens were mobilised by a mantle plume that eroded the lithosphere and provided the heat source for the volcanism. During explosive volcanism, halogens were transported into the upper atmosphere with globally devastating effects for the ozone layer. Tropospheric ozone helps prevent ultra-violet light from penetrating to ground level. Without this protective layer, the Earth’s surface would have been exposed to deadly levels of radiation resulting in genetic mutations, infertility and species decline. Understanding the process of collapse and recovery of ozone levels, will help in predicting the biological impacts of future volcanic eruptions.
- Large Igneous Province are huge accumulations of igneous rocks, formed from sustained periods of eruptions of lava and subsurface intrusions
- Lithosphere is is the rigid outer shell of the Earth extending up to 150km in depth
- Mantle xenolith is a fragment of the mantle picked up and carried to the surface by a magma.