AN ASTONISHING DISCOVERY

A group of scientists from various universities have discovered that oxygen appeared first in Earth’s atmosphere about 50 to 100 million years earlier than was previously believed. Drilling deep into the earth’s crust they extracted a kilometre-long core of sedimentary rock.

They analyzed the amounts of the trace metals molybdenum, rhenium and uranium in the sediment. The amounts of these metals in oceans and sediments depend on the amount of oxygen in the environment.
Analyzing the layers of sedimentary rock in the sample the researchers report finding evidence that a small but significant amount of oxygen — a whiff — was present in the oceans and possibly Earth’s atmosphere 2.5 billion years ago.
The data also suggest that oxygen was nearly undetectable just before that time. For the first half of Earth’s 4.56-billion-year history, the environment held almost no oxygen, other than bound to hydrogen in water (H{-2}O) or to silicon and other elements in rocks.
Then, some time between 2.3 and 2.4 billion years ago, oxygen rose sharply in the Earth’s atmosphere and oceans. Scientists call this the Great Oxidation Event.
The scientists analyzed the drill core for geochemical and biological tracers representing the time just before the rise of atmospheric oxygen.

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ZAID KAMAAL