New Interpretation of Evidence from Cretaceous Mass Extinction
New Zealand led Team shed new light on Dinosaur Extinction
Research published this week in the scientific journal “Geology”, puts a different interpretation on evidence from the famous K-T boundary and the Cretaceous mass extinction event. This new research which has involved an international team of geologists studying a number of marine and non-marine sites on the Mesozoic/Cenozoic boundary sheds new light on the cause of the forest fires resulting from the asteroid impact on the Yucatan peninsula in Mexico.
Cretaceous Mass Extinction
Around 65 million years ago, a huge extraterrestrial object crashed into the Earth, blasting a crater over 200 kilometres across and throwing huge quantities of material up into the atmosphere.
The research team, headed by New Zealand geologist Mark Harvey has contradicted conventional theory concerning the Chicxulub impact that is believed to have hastened the demise of the dinosaurs.
According to Mr Harvey, the impact itself did cause extensive forest fires that destroyed the planet’s ecosystems. This new work blames the large carbon deposits in the sediments that were struck. In this newly published paper it is claimed that the extraterrestrial object smashed into oil or coal deposits with such force that the carbon was liquefied and hurled skywards, forming tiny airborne beads that blanketed the Earth in soot.
Studying the Ash Fall
Up until now, many scientists believed that the carbon resulting from the impact was ash resulting from global forest fires. The international team, consisting of researchers from the USA, New Zealand, Italy and Britain, found some particles among the soot had formed carbon “cenospheres”, tiny beads similar to ones produced in modern times by intense industrial combustion.
“Carbon cenospheres are a classic indicator of industrial activity,” Mark Harvey, the lead author stated. “The first appearance of the carbon cenospheres defines the onset of the industrial revolution.”
Some burnt vegetation has been found in the layer close to the impact site, but scientists think these fires broke out as molten rock and super-hot ash fell from the sky and on to forests.
Researchers had suggested mass extinctions came as global forest fires pumped enough carbon dioxide into the atmosphere to cause a period of runaway global warming, or they spewed enough soot to block out the sun and kill off the plants that disrupted and destroyed global food chains.
The Chicxulub Crater
Mr Harvey’s team found cenospheres were smaller the further the sample site was from the Chicxulub Crater – consistent with heavier particles produced by the impact falling to earth sooner than lighter particles. It is estimated that 900 billion tonnes of carbon cenospheres were ejected by the collision.
Conventional theory had speculated that soot in the form of charcoal particles found in the strata at the K-T boundary was thought to be evidence for fires that initially swept across the Americas, and then extended world-wide, sparked off by electric storms setting alight to dead and dying vegetation.
Incidentally, the layer, rich in the rare Earth element Iridium called the K-T boundary is so called because the “K” is short for kreide, the German word for chalk vast amounts of chalk were formed during the end of the Cretaceous. The “T” is short for Tertiary.
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