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The Origin of Isotopic Variations in Meteorites

Presentation #142.08 in the session “Sun and Solar System”.

Published onJan 11, 2021
The Origin of Isotopic Variations in Meteorites

One of the principal goals of planetary science is to try and understand how our Solar System formed and evolved. Stable isotopic analyses can give important information on the evolution and structure of the solar nebula. For example, oxygen isotopic analyses can help to identify different meteorite parent bodies with relevant data plotted on a three oxygen isotopic plot. Chromium, titanium, molybdenum, and nickel isotopes have been used to place Solar System materials into two distinct groups: the carbonaceous chondrite (CC) and non-carbonaceous (NC) groups. We are currently investigating the origin of these isotopic differences and what they imply about the formation locations of different meteorite parent bodies. Previously to explain the oxygen isotopic differences, isotopic self-shielding has been invoked, which results in 17O- and 18O-rich ice and 16O-rich dust. The icy material would have formed past the snow line and then drifted inwards, The dust and ice would have come together to form the precursors of the meteorites we study today. We are investigating whether trends among chondritic and achondritic material on the three oxygen isotopic plot could be related to the incorporation of 16O-rich calcium-aluminum-rich inclusions (CAIs) and amoeboid olivine condensates (AOAs), which were subsequently destroyed. The CAIs and AOAs that are analyzed today would have been injected later or “luckily” escaped destruction. We are also studying the origin of the CC and NC groups. The isotopic variations for chromium, titanium, and molybdenum are believed to be due to nucleosynthetic processes prior to the formation of the Solar System. Presolar stardust grains tend to have large anomalies in these isotopes. CAIs and AOAs, which appear to have formed close to the Sun, also have large anomalies. By investigating the origin of all these isotopic variations, we hope to gain insight on the distribution of material in the solar nebula.


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