DAVIS, Calif., Sept. 1 (UPI) -- At the bottom of an icy lake in Antarctica is a thin layer of green slime. As researchers only recently discovered, the oxygen-producing slime has created a modern replica of early Earth -- the first of its kind.
The lakebed and its sliver of concentrated oxygen recalls a young Earth, as it existed before oxygen became abundant and accumulated in the atmosphere.
By studying Lake Fryxell and the surrounding McMurdo Dry Valleys, geoscientists at the University of California, Davis say they may be able to learn more about this little understood part of Earth's early evolution.
Scientists know that around 2.4 billion years ago, oxygen (in the form of ozone) stretched from the Earth's surface to the upper atmosphere. Its appearance in the geologic record is known as the Great Oxidation Event. But scientists know little about geochemical events that precipitated oxygen's rise.
The oasis of oxygen at the bottom of Lake Fryxell may offer clues as to what Earth was like as bacteria first evolved the ability to photosynthesize. While many Dry Valley lakes' deeper waters are anoxic, Lake Fryxell becomes anoxic at a depth where light still penetrates.
"The thought is, that the lakes and rivers were anoxic, but there was light available, and little bits of oxygen could accumulate in the mats," Dawn Sumner, a professor of Earth and planetary sciences at UC Davis, said in a press release.
At the very least, its particulars will help scientists locate other oxygen oases by showing researchers what to look for in ancient rocks.
Sumner and a team of her colleagues and students are analyzing the chemical reactions between the sliver of oxygen and the anoxic water above.
Their initial discovery of the oxygen oasis is detailed in the latest issue of the journal Geology.