One of the prime suspects for 鈥渢he crime of the Cretaceous鈥� 鈥� the killing-off of the dinosaurs 鈥� may have hidden evidence of its guilt inside a rare time-capsule.
The biggest volcanic eruptions are called flood events, which release millions of cubic kilometres of lava and all the gases trapped within it. One of the main theories about mass extinctions is that such flood events could have pumped sulphur and chlorine into the atmosphere, killing off anything nearby.
鈥淏ut it鈥檚 not just poisoning by the pollutants,鈥� says of the Open University in the UK. 鈥淭here can be a whole lot of knock-on effects to the environment.鈥�
Advertisement
However, geologists haven鈥檛 been sure that enough of the gases were released to effect large-scale climate change, and thus contribute to extinctions.
To investigate that, Blake and his colleagues scoured the Deccan Traps, a region in India that was formed by a flood event about 65 million years ago. They were looking for rare nuggets called glass inclusions.
Because they form at high pressures beneath the surface, these inclusions hold a record of the gases in the magma before eruption. The team analysed the inclusions鈥� composition and estimated that at least 10 million million tonnes of sulphur and chlorine were pumped into the atmosphere at the time of the flood event.
That鈥檚 more than enough to make volcanic activity look more like the culprit for extinctions.
鈥淭his much sulphur strengthens the case for volcanism to do lots of environmental damage,鈥� Blake says.
Journal ref: ,
