The researchers studied chemical elements in samples of limestone taken from northern Iran, which was a shallow tropical ocean during the Early Triassic period, from about 252 to 248 million years ago.
The study provides the first-ever link between the elements strontium and carbon that were deposited in the rock at that time. Both changed in ways that indicate dramatic climate change was taking place in the world above.
When the rock they studied was being formed 250 million years ago, all of Earth's continents were joined together in a super-continent called Pangea. Up to 90 percent of marine species and 70 percent of land vertebrates had just been killed by massive volcanic eruptions from the region now called the Siberian Traps, which covers much of northern Asia.
What caused the eruptions is not certain.
The consequences are certain, however: the volcanoes spewed enough molten rock to cover millions of square miles, and enough greenhouse gases to dramatically increase Earth's temperature.
The limestone used in this new study came from collaborators in Austria, who retrieved it from a gorge in the region of Zal, near the northern Iranian border.
The Austrian researchers measured the amount of carbon in the rock, and confirmed that Earth's natural carbon cycle and climate were unstable for 5 million years after the Great Dying.
Colleagues at the University of Cincinnati, who worked with the Austrian researchers, demonstrated that large amounts of sediment were collecting in the ocean. They then sent the samples to Ohio State, where Sedlacek and Saltzman measured the ratio of two forms of strontium, strontium-87 and strontium-86. This ratio is an indicator of how much bedrock was being weathered away from the Earth's surface.
They found that as the carbon level
|Contact: Pam Frost Gorder|
Ohio State University