The earth has been bombarded by meteorites throughout its long history. Meteorite impacts generate atmospheric dust and cover the Earth’s surface with debris and have long been considered as a trigger of mass extinctions through Earth’s history.
A multidisciplinary research team from the University of Liverpool and the Instituto Tecnológico y de Energías Renovables, Tenerife with expertise in palaeontology, asteroid stratigraphy, mineralogy, cloud microphysics and climate modelling, sought to explore why some meteorites have caused mass extinctions, for example the K/Pg Chixulclub impact that killed off dinosaurs, yet many which are larger in size have not.
They analysed 44 impacts over the past 600 million years using a new method: assessing the mineral content of the dust ejected into the atmosphere upon impact.
Their findings, published in the Journal of the Geological Society of London, reveal that meteorites that hit rocks rich in potassium feldspar (a common and rather benign mineral) always correspond with a mass extinction episode, irrespective of size.
Potassium feldspar is non-toxic. However, it is a powerful ice-nucleating mineral aerosol that strongly affects cloud dynamics, which makes them let through more solar radiation. This in turn warms up the planet and changes the climate. The atmosphere also becomes more sensitive to warming from greenhouse gas emissions, such as large volcanic eruptions.
Liverpool sedimentologist, Dr Chris Stevenson, from the University’s school of Earth, Ocean and Ecological Sciences co-authored the study.
He said: “For decades scientists have puzzled over why some meteorites cause mass extinctions, and others, even really big ones, don’t.
