Rocks, fossils, and other natural relics hold clues to ancient environments in the form of different ratios of isotopes—atomic variants of elements with the same number of protons but different numbers of neutrons. Seawater, rain water, oxygen, and ozone, for instance, all have different ratios, or fingerprints, of the oxygen isotopes 16O, 17O, and 18O. Weathering, ground water, and direct deposition of atmospheric aerosols change the ratios of the isotopes in a rock revealing a lot about the past climate.

Douglas Rumble’s research is centered on these three stable isotopes of oxygen and the four stable isotopes of sulfur 32S , 33S , 34S, and 36S. In addition to revealing what happened in Earth’s past, he uses oxygen isotopes to distinguish processes that occurred in the solar nebula from those taking place in planetary bodies after their condensation from the nebula.

The four stable sulfur   isotopes also provide insights into the evolution of Earth’s atmosphere in the form of anomalous separations recorded in sulfur-bearing minerals from rocks as old as 3.8 billion years.

To understand Earth's earliest history--its formation from Solar System material into the present-day layering of metal core and mantle, and crust—Rumble and team look to meteorites. Recently they looked at a particularly old type of meteorite called diogenites and examined then using an array of techniques, including precise analysis of certain elements for important clues to some of the Solar System's earliest chemical processing.

Diogenites represent some of the Solar System's oldest existing examples of heat-related chemical processing. The Rumble team examined nine diogenites and confirmed that these samples came from no fewer than two parent bodies and that the crystallization of their minerals occurred about 4.6 billion years ago, only 2 million years after condensation of the oldest solids in the Solar System giving researchers us a better picture of the earliest days of our Solar System.

Rumble received his B.A in geology from Columbia University and his Ph. D. from Harvard University.  He was then a postdoctoral fellow at Carnegie and went on to become an assistant professor at UCLA before joining the scientific staff at Carnegie in 1973. For more see

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Widmanstatten pattern characteristic of iron meteorites, courtesy of Peng Ni.
August 3, 2020

Washington, DC— Work led by Carnegie’s Peng Ni and Anat Shahar uncovers new details about our Solar System’s oldest planetary objects, which broke apart in long-ago collisions to form iron-rich meteorites.  Their findings reveal that the distinct chemical signatures of these meteorites can be explained by the process of core crystallization in their parent bodies, deepening our understanding of the geochemistry occurring in the Solar System’s youth. They are published by Nature Geoscience.

Many of the meteorites that shot through our planet’s atmosphere and crashed on its surface were once part of larger objects that broke up at some point in our

Earth's magnetic field shields it from ionizing particles
July 6, 2020

Washington, DC— How did the chemical makeup of our planet’s core shape its geologic history and habitability?

Life as we know it could not exist without Earth’s magnetic field and its ability to deflect dangerous ionizing particles from the solar wind and more far-flung cosmic rays. It is continuously generated by the motion of liquid iron in Earth’s outer core, a phenomenon called the geodynamo.

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Comparing carbon's compatibility with silicates and with iron
March 31, 2020

Washington, DC— Carbon is essential for life as we know it and plays a vital role in many of our planet’s geologic processes—not to mention the impact that carbon released by human activity has on the planet’s atmosphere and oceans. Despite this, the total amount of carbon on Earth is a mystery, because much of it remains inaccessible in the planet’s depths.  

New work published this week in Proceedings of the National Academy of Sciences reveals how carbon behaved during Earth’s violent formative period. The findings can help scientists understand how much carbon likely exists in the planet’s core and the contributions it could make

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Belin changed course for her postdoctoral work, in



Kostova received a B.S. in Biology from the
