Meteorites reveal likely origin of Earth's volatile chemicals

Date:
January 27, 2023
Source:
Imperial College London
Summary:
By analyzing meteorites, researchers have uncovered the likely
far-flung origin of Earth's volatile chemicals, some of which form
the building blocks of life.


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FULL STORY ==========================================================================
By analysing meteorites, Imperial researchers have uncovered the likely
far- flung origin of Earth's volatile chemicals, some of which form the building blocks of life.


==========================================================================
They found that around half the Earth's inventory of the volatile
element zinc came from asteroids originating in the outer Solar System
-- the part beyond the asteroid belt that includes the planets Jupiter,
Saturn, and Uranus. This material is also expected to have supplied
other important volatiles such as water.

Volatiles are elements or compounds that change from solid or liquid
state into vapour at relatively low temperatures. They include the six
most common elements found in living organisms, as well as water. As such,
the addition of this material will have been important for the emergence
of life on Earth.

Prior to this, researchers thought that most of Earth's volatiles came
from asteroids that formed closer to the Earth. The findings reveal
important clues about how Earth came to harbour the special conditions
needed to sustain life.

Senior author Professor Mark Rehka?mper, of Imperial College London's Department of Earth Science and Engineering, said: "Our data show that
about half of Earth's zinc inventory was delivered by material from the
outer Solar System, beyond the orbit of Jupiter. Based on current models
of early Solar System development, this was completely unexpected."
Previous research suggested that the Earth formed almost exclusively
from inner Solar System material, which researchers inferred was the predominant source of Earth's volatile chemicals. In contrast, the
new findings suggest the outer Solar System played a bigger role than previously thought.

Professor Rehka?mper added: "This contribution of outer Solar System
material played a vital role in establishing the Earth's inventory
of volatile chemicals. It looks as though without the contribution of
outer Solar System material, the Earth would have a much lower amount
of volatiles than we know it today -- making it drier and potentially
unable to nourish and sustain life." The findings are published today
in Science.

To carry out the study, the researchers examined 18 meteorites of varying origins -- eleven from the inner Solar System, known as non-carbonaceous meteorites, and seven from the outer Solar System, known as carbonaceous meteorites.

For each meteorite they measured the relative abundances of the five
different forms -- or isotopes -- of zinc. They then compared each
isotopic fingerprint with Earth samples to estimate how much each of these materials contributed to the Earth's zinc inventory. The results suggest
that while the Earth only incorporated about ten per cent of its mass from carbonaceous bodies, this material supplied about half of Earth's zinc.

The researchers say that material with a high concentration of zinc and
other volatile constituents is also likely to be relatively abundant in
water, giving clues about the origin of Earth's water.

First author on the paper Rayssa Martins, PhD candidate at the Department
of Earth Science and Engineering, said: "We've long known that some carbonaceous material was added to the Earth, but our findings suggest
that this material played a key role in establishing our budget of
volatile elements, some of which are essential for life to flourish."
Next the researchers will analyse rocks from Mars, which harboured water
4.1 to 3 billion years ago before drying up, and the Moon. Professor
Rehka?mper said: "The widely held theory is that the Moon formed when
a huge asteroid smashed into an embryonic Earth about 4.5 billion
years ago. Analysing zinc isotopes in moon rocks will help us to test
this hypothesis and determine whether the colliding asteroid played an important part in delivering volatiles, including water, to the Earth."
This work was funded by the Science and Technology Facilities Council
(STFC - - part of UKRI) and Rayssa Martins is funded by an Imperial
College London Presidents' PhD Scholarship.

* RELATED_TOPICS
o Matter_&_Energy
# Solar_Energy # Materials_Science # Nature_of_Water
o Earth_&_Climate
# Earth_Science # Near-Earth_Object_Impacts # Geology
o Fossils_&_Ruins
# Origin_of_Life # Early_Climate # Fossils
* RELATED_TERMS
o Recent_single-origin_hypothesis o Timeline_of_evolution o
Amino_acid o Water o Earth o Dead_zone_(ecology) o Fullerene
o Gravitation

========================================================================== Story Source: Materials provided by Imperial_College_London. Original
written by Caroline Brogan. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Rayssa Martins, Sven Kuthning, Barry J. Coles, Katharina Kreissig,
Mark
Rehka"mper. Nucleosynthetic isotope anomalies of zinc in meteorites
constrain the origin of Earth's volatiles. Science, 2023; 379
(6630): 369 DOI: 10.1126/science.abn1021 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/01/230127131132.htm

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