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5 December 2013 11:26 am ,
Vol. 342 ,
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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There's Life in That Oil!
9 June 2005 (All day)
The world's oldest oil contains clues that early Earth may have been a livelier place than previously believed. The findings indicate that the ocean was teeming with primitive organisms 3.2 billion years ago, just over a billion years after the planet formed.
The first traces of life appear in the fossil record around 3.5 billion years ago in the form of microbial mounds in Western Australia known as stromatolites. But most rocks this age have been heated and reheated so much that any fossils they may have contained are gone. So just how extensive life was during this period remained a mystery. In 1998, a team led by geologist Birger Rasmussen of the University of Western Australia discovered microscopic drops of fluid oil preserved within mineral grains (similar to gas bubbles trapped in an ice cube) in rocks more than 3 billion years old in Australia's Pilbara region. But scientists suggested that unlike the oil on Earth today, which formed from dead organisms, the ancient oil could have formed through nonbiological processes.
Now, Rasmussen has found evidence that oil in 3.2-billion-year-old rocks in Western Australia was produced from decayed organic matter. He studied two well-preserved sequences of black shale, a type of rock that often contains organic matter and can produce oil under the right conditions. One shale is 3.2 billion years old, and the other 2.6 billion years old. In both sequences, he found thin, discontinuous streaks of kerogen, a waxy precursor to fossil fuels formed from organic matter and commonly found in much younger shales that are known oil producers. Both shales also contained microscopic nodules of bitumen, a tarlike remnant left behind when oil migrates out of the shale. Rasmussen, who reports his results in the current issue of Geology, believes the abundance and extent of the kerogen in the shales indicates the ocean was already teeming with enough single-celled life 3.25 billion years ago to support widespread oil generation.
"If we take this as globally representative, then it is impressive," says biogeochemist John Hayes of Woods Hole Oceanographic Institution in Massachusetts. But don't go pointing your drilling rigs at older rocks just yet, he cautions. Hayes believes that a fundamental change in the carbon cycle around 570 million years ago made younger rocks better at turning dead organisms into oil.
Abstract of study