Oxygen on early Earth may have come from quartz crushed by earthquakes
Billions of years ago, crushed quartz reacting with water could have created the conditions needed for the evolution of the photosynthetic microbes responsible for most of the oxygen now in Earth’s atmosphere
By James Dinneen
20 March 2023
Veins of white quartz on the north-east coast of the US
Richard Berube / Alamy Stock Photo
Earthquakes and other geological processes may have enabled oxygen-producing reactions that shaped the evolution of some of Earth’s earliest organisms.
Today, oxygen makes up around a fifth of Earth’s atmosphere, with most of it produced by plants and microbes. It didn’t start that way. There was very little oxygen in the atmosphere until levels spiked during the Great Oxidation Event between 2.4 billion and 2.3 billion years ago thanks to the rapid spread of microbes that release oxygen through photosynthesis.
However, the widespread presence of antioxidant enzymes across the tree of life suggests a common ancestor that existed prior to the Great Oxidation Event was exposed to some amount of oxygen.
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Mark Thiemens at the University of California, San Diego, and his colleagues ground up quartz rock and exposed it to water under chemical conditions similar to those on Earth prior to high levels of oxygen. The researchers used quartz because it is the simplest and most common silicate mineral.
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They found that the broken crystals on the surface of quartz can react with water to form molecular oxygen and other reactive oxygen species, such as hydrogen peroxide. Also known as free radicals, these molecules would have been critical to early evolution because they can damage DNA and other components of cells, says Timothy Lyons at the University of California, Riverside, who wasn’t involved with the work.
