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Science Blog ZINC PROJECTS

Nickel famine could increase oxygen level in early Earth

Date: 13-May-09
Author: Carnegie Institution of Washington

The Earth's original atmosphere held very little oxygen. This began to change around 2.4 billion years ago when oxygen levels increased dramatically during what scientists call the "Great Oxidation Event." The cause of this event has puzzled scientists, but researchers have found indications in ancient sedimentary rocks that it may have been linked to a drop in the level of dissolved nickel in seawater.

The researchers, led by Kurt Konhauser of the University of Alberta in Edmonton, analyzed the trace element composition of sedimentary rocks known as banded-iron formations, or BIFs, from dozens of different localities around the world, ranging in age from 3,800 to 550 million years.

Banded iron formations are unique, water-laid deposits often found in extremely old rock strata that formed before the atmosphere or oceans contained abundant oxygen. As their name implies, they are made of alternating bands of iron and silicate minerals. They also contain minor amounts of nickel and other trace elements.

Banded iron formations like this from northern Michigan contain evidence of a drop in dissolved nickel in ancient oceans. Courtesy: Carnegie Institution

The researchers found that nickel levels in the BIFs began dropping around 2.7 billion years ago and by 2.5 billion years ago was about half its earlier value.

Full story: Did a Nickel Famine Trigger the "Great Oxidation Event"?