Carnegie Institution for Science | 2016 Apr 28
[img3="An illustration of how laboratory techniques can tell scientists like Anat Shahar and her team about how elements such as iron behave under the extreme pressures found in the Earth’s core. (Credit: Vadim Sadovski/Anat Shahar)"]https://carnegiescience.edu/sites/carne ... ation2.jpg[/img3][hr][/hr]New work from a research team led by Carnegie’s Anat Shahar contains some unexpected findings about iron chemistry under high-pressure conditions, such as those likely found in the Earth’s core, where iron predominates and creates our planet’s life-shielding magnetic field. Their results, published in Science, could shed light on Earth’s early days when the core was formed through a process called differentiation—when the denser materials, like iron, sunk inward toward the center, creating the layered composition the planet has today.
Earth formed from accreted matter surrounding the young Sun. Over time, the iron in this early planetary material moved inward, separating from the surrounding silicate. This process created the planet’s iron core and silicate upper mantle. But much about this how this differentiation process occurred is still poorly understood, due to the technological impossibility of taking samples from the Earth’s core to see which compounds exist there.
Seismic data show that in addition to iron, there are “lighter” elements present in the core, but which elements and in what concentrations they exist has been a matter of great debate. This is because as the iron moved inward toward the core, it interacted with various lighter elements to form different alloyed compounds, which were then carried along with the iron into the planet’s depths.
Which elements iron bonded with during this time would have been determined by the surrounding conditions, including pressure and temperature. As a result, working backward and determining which iron alloy compounds were created during differentiation could tell scientists about the conditions on early Earth and about the planet’s geochemical evolution. ...
Pressure-dependent isotopic composition of iron alloys - A. Shahar et al
- Science 352(6285):580 (29 Apr 2016) DOI: 10.1126/science.aad9945