The Volatile Processes that
Shaped Earth
Oxford University
light on how the Earth was first formed.
Oxford , England
Although it is widely understood that Earth was formed gradually, from much smaller bodies, many of the processes involved in shaping our growing planet are less clear. In a new study featured on the cover of the latest edition of Nature, researchers from theUniversity
of Oxford
It is well known that the Earth is strongly depleted, relative to the solar system as a whole, in those elements which condensed from the early gas disc at temperatures less than 1000°C (for example, lead, zinc, copper, silver, bismuth, and tin). The conventional explanation is that the Earth grew without these volatile elements and small amounts of an asteroidal-type body were added later. This idea cannot, however, explain the “over abundance” of several other elements – notably, indium, which is now used in semiconductor technologies, as well as TV and computer screens.
Postgraduate student Ashley Norris and Bernard Wood, Professor of Mineralogy atOxford
During the experiments each of the elements of interest evaporated by different amounts. The lava samples were then rapidly cooled and the patterns of element loss determined by chemical analysis. The analyses revealed that the relative losses (volatilities) measured in the molten lava experiments agree very closely with the pattern of depletion observed in the Earth. In particular, indium volatility agrees exactly with its observed abundance in the Earth - its abundance, turns out not to be an anomaly.
Professor Bernard Wood said: ‘Our experiments indicate that the pattern of volatile element depletion in the Earth was established by reaction between molten rock and an oxygen-poor atmosphere. These reactions may have occurred on the early-formed planetesimals which were accreted to Earth or possibly during the giant impact which formed the moon and which is believed to have caused large-scale melting of our planet.’
Ashley Norris said: ‘Our work shows that interpretation of volatile depletion patterns in the terrestrial planets needs to focus on experimental measurement of element volatilities.’
Having focused their original experiments on 13 key elements, the team are in the process of looking at how other elements, such as chlorine and iodine, behave under the same conditions.
light on how the Earth was first formed.
Although it is widely understood that Earth was formed gradually, from much smaller bodies, many of the processes involved in shaping our growing planet are less clear. In a new study featured on the cover of the latest edition of Nature, researchers from the
It is well known that the Earth is strongly depleted, relative to the solar system as a whole, in those elements which condensed from the early gas disc at temperatures less than 1000°C (for example, lead, zinc, copper, silver, bismuth, and tin). The conventional explanation is that the Earth grew without these volatile elements and small amounts of an asteroidal-type body were added later. This idea cannot, however, explain the “over abundance” of several other elements – notably, indium, which is now used in semiconductor technologies, as well as TV and computer screens.
Postgraduate student Ashley Norris and Bernard Wood, Professor of Mineralogy at
During the experiments each of the elements of interest evaporated by different amounts. The lava samples were then rapidly cooled and the patterns of element loss determined by chemical analysis. The analyses revealed that the relative losses (volatilities) measured in the molten lava experiments agree very closely with the pattern of depletion observed in the Earth. In particular, indium volatility agrees exactly with its observed abundance in the Earth - its abundance, turns out not to be an anomaly.
Professor Bernard Wood said: ‘Our experiments indicate that the pattern of volatile element depletion in the Earth was established by reaction between molten rock and an oxygen-poor atmosphere. These reactions may have occurred on the early-formed planetesimals which were accreted to Earth or possibly during the giant impact which formed the moon and which is believed to have caused large-scale melting of our planet.’
Ashley Norris said: ‘Our work shows that interpretation of volatile depletion patterns in the terrestrial planets needs to focus on experimental measurement of element volatilities.’
Having focused their original experiments on 13 key elements, the team are in the process of looking at how other elements, such as chlorine and iodine, behave under the same conditions.
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