Even Without a Meteorite, The Stage Was Set For Dinosaurs to Go Extinct

Extraits de l'article:

A new analysis by an international team of researchers has added evidence to claims that the world prior to the asteroid blow was anything but paradise, with measures of sulfur in the atmosphere reaching critical levels.

Together with other studies on levels of mercury, the research provides a signature of volcanic activity strong enough to cause significant climate disruptions.

In 1991, the timing of this volcanic activity had been dismissed as too early to be behind the mass extinction event but more recent studies demonstrate it's possible the timing was close enough to be significant.

"Our data suggest that volcanic sulfur degassing from such activity could have caused repeated short-lived global drops in temperature," University of Oslo geoscientist Sara Callegaro and colleagues write in their paper.

The team examined rocks from the Deccan Traps – one of the largest volcanic features – in what's now West India. They applied a new technique they developed for measuring sulfur concentrations.

Models suggest sustained sulfur emissions from the Deccan Traps were enough to substantially alter the global climate. This volcanic region alone released a staggering one million cubic kilometers of molten rock.

What's more, formation of the highly concentrated sulfur containing lava at Thakurvadi to Bushe, within the region, coincides with the cooling Cretaceous climate, the team notes.

While much of the basalt in the area is generally low in sulfur, this could indicate the climate – cooling molecule was slowly released into the atmosphere from the hardened magma following eruptions.

As a result global temperatures could have plummeted in bouts of up to 10°C, between rapid recovery periods, within 100,000 years before the Chicxulub meteor delivered that final blow.