By Timothy Kudo
Daily Bruin Senior Staff
Liquid water may have existed on Earth 4.3 billion years ago,
according to research published in the Jan. 11 issue of Nature by
UCLA researchers.
The discovery lends more credence to the possibility of life
existing within 200 million years of the Earth’s formation
““ hundreds of millions of years earlier than previously
thought.
“We’re attempting to understand our physical
environment and a big question is, “˜Where do we come
from?’ This is a very small incremental addition to
that,” said T. Mark Harrison, professor of geochemistry and
co-author of the report.
The research was conducted on a rock discovered 15 years ago in
an area of Western Australia known as Jack Hills. Though the rock
was previously dated to be about 3 billion years old, it contained
traces of much older elements that previously couldn’t be
dated due to lack of technology.
By using UCLA’s high-resolution ion-microprobe, a device
that dates and determines the composition of exceedingly small
samples, researchers were able to determine that the amount of a
type of oxygen present in ancient Zircon strands in the rock came
about because of the presence of water.
Previously, scientists could only find the average age of a
large sample and thus, if elements on the edge of the rock were
younger than elements in the middle, they would have averaged out
to produce a less piquant date.
“What we can do is point the microprobe to a very fine,
sometimes 10 times smaller than the width of one of the hairs on
your head, sample and we’re able to segregate little
sub-domains to see how the age varies,” Harrison said.
The finding sheds light on a period of geologic history, known
as the “dark ages of Earth’s history,” from
shortly after the creation of the earth 4.6 billion years ago to
the discovery of the oldest rocks and life around 4 billion years
ago.
Scientists knew that the other two requisites for life
““Â energy provided by the sun, and organic compounds from
meteorites or comets ““ existed at the time, but until this
discovery, didn’t have the last piece of the puzzle:
water.
The use of the ion-microprobe in the discovery may shed light on
finding life on other planets.
“If this technique demonstrates the existence of water
early in Earth’s history, it could feasibly be applied to
other bodies,” said Bruce Runnegar, professor of earth and
space sciences.
The fact that scientists were able to make the discovery is in
itself amazing because very little is able to survive for billions
of years, said Stephen Mojzsis, a former UCLA postdoctoral scholar
in Harrison’s laboratory who was the lead author of the
report.
“The geographic record can be thought of as a really old
antique rug,” said Mojzsis, who is now an assistant professor
at the University of Colorado at Boulder. “If you have this
rug on the floor, over time people walk over the rug until it wears
away and all you have is fragments and a couple pieces.”
“These things are tiny, but extremely interesting,”
he added.
Now, this process should be applied to even older rocks to see
how far back the existence of water can be dated, Mojzsis said.
“If we could hold in our hand a rock that’s 4.3
billion years old, that would be like a Rosetta Stone for solar
history,” Harrison said.
After they made the discovery, Mojzsis drove to Santa Monica and
sat on the beach next to the pier looking out over the ocean with
the new found realization that the substance in front of him had
been around for over 4 billion years before.
“It was an amazing experience,” said Mojzsis.
“As a scientist when you make discoveries like this, it could
be in any field, you know something that other people didn’t
know before, you’re in a place … where you have new
eyes.”