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Updated: Apr 20, 2026
09:31
Preparation of Authigenic Pyrite from Methane-bearing Sediments for In Situ Sulfur Isotope Analysis Using SIMS
Published on: August 31, 2017
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Early inner solar system origin for anomalous sulfur isotopes in differentiated protoplanets
Michael A Antonelli1, Sang-Tae Kim2, Marc Peters3
1Department of Geology, University of Maryland, College Park, MD 20742; mantonelli@berkeley.edu.
Summary
Sulfur isotope depletions in IIIF iron meteorites suggest early solar system photochemistry. These findings support the idea that differentiated planetesimals inherited sulfur from the inner solar system, impacting S-isotope compositions.
Area of Science:
- Cosmochemistry
- Isotope Geochemistry
- Planetary Science
Background:
- Achondrite meteorites show anomalous sulfur-33 ((33)S) enrichments, attributed to solar nebula photochemistry.
- Previous studies failed to find predicted (33)S depletions, questioning the origins of these anomalies or the bulk solar system sulfur isotope composition.
Purpose of the Study:
- To investigate anomalous sulfur isotope compositions in meteorites.
- To test hypotheses regarding photochemical origins of sulfur anomalies in the early solar system.
Main Methods:
- Analysis of sulfur isotope compositions, specifically (33)S, in IIIF and other magmatic iron meteorite groups.
- Comparison of meteorite sulfur isotope data with models of solar nebula chemistry.
Main Results:
- Discovery of significant anomalous (33)S depletions (<-0.02 per mil) in IIIF iron meteorites.
- Observation of (33)S enrichments in other magmatic iron meteorite groups.
- Correlation between sulfur isotopes and Hf-W core segregation ages observed.
Conclusions:
- Differentiated planetesimals likely inherited photochemically processed sulfur from the inner solar system.
- The bulk inner solar system sulfur isotope composition is likely chondritic.
- Sulfur isotope variations may reflect nebular location and volatile content, potentially linked to core segregation processes.
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