Meteorites reveal likely origin of Earth’s volatile chemicals
(ORDO NEWS) — Meteorites have told researchers about the likely distant origin of Earth‘s volatile chemicals, some of which make up the building blocks of life.
They found that about half of the earth’s reserves of the volatile element zinc are asteroids originating from the outer solar system – the part beyond the asteroid belt, which includes the planets Jupiter, Saturn and Uranus. It is assumed that other important volatiles, such as water, were obtained from this material.
Volatile substances are elements or compounds that change from solid or liquid to vapor at relatively low temperatures.
These include the six most common elements found in living organisms, as well as water. Thus, the addition of this material was of great importance for the origin of life on Earth.
Prior to this, researchers thought that most of the Earth’s volatiles came from asteroids that formed closer to Earth. The finds reveal important clues about how Earth developed the special conditions needed to sustain life.
Senior author Professor Mark Recamper, from Imperial College London’s Department of Geosciences and Engineering, said: “Our data indicate that about half of Earth’s zinc supply was brought in from the outer solar system, outside the orbit of Jupiter.
Based on current models of the early development of the solar system, this was completely unexpected.”
Previous research has suggested that the Earth formed almost exclusively from the solar system’s inner material, which researchers believe was the Earth’s predominant source of volatile chemicals. The new results show that the outer solar system played a larger role than previously thought.
Professor Recamper added: “This contribution of material from the outer solar system has played a vital role in creating the stock of volatile chemicals on Earth.
It appears that without the contribution of material from the outer solar system, Earth would have far less volatiles than we know today – making it drier and potentially unable to nourish and support life.”
To conduct the study, the scientists studied 18 meteorites of various origins – 11 from the inner solar system, known as non-carbonaceous meteorites, and 7 from the outer solar system, known as carbonaceous meteorites.
For each meteorite, they measured the abundances of five different zinc isotopes. They then compared each isotopic fingerprint with Earth’s samples to assess how much each of these materials contributed to the Earth’s zinc reserves.
The results show that although the Earth is only about 10% of its mass carbonaceous bodies, this material provides about half of the Earth’s zinc.
The material with high concentrations of zinc and other volatiles is likely also relatively abundant in water, the researchers said, providing clues to the origin of Earth’s water.
Raissa Martins, Ph.D., Ph.D. in Earth Sciences and Engineering, said: “We have known for a long time that some carbonaceous material has been added to the Earth, but the results show that this material played a key role in establishing our balance of volatile elements, some of necessary for the flourishing of life.”
The researchers will then analyze rocks from Mars, which contained water from 4.1 to 3 billion years ago before drying up, and from the Moon. Professor Recamper said: “A widely held theory is that the Moon was formed when a huge asteroid hit the Earth about 4.5 billion years ago.
Analysis of zinc isotopes in lunar rocks will help us test this hypothesis and determine whether the asteroid impact played a significant role in delivering volatiles, including water, to Earth.”
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