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Early aqueous activity on primitive meteorite parent bodies
M Endress1, E Zinner, A Bischoff
1Institute of Planetology, University of Münster, Germany.
Nature
|February 22, 1996
Summary
Aqueous alteration in meteorites occurred early in the solar system, less than 20 million years after the formation of the oldest solar-nebula condensates. This finding refines our understanding of early solar system processes and meteorite evolution.
Area of Science:
- Cosmic Chemistry
- Planetary Science
- Geochronology
Background:
- The early solar system experienced significant chemical and physical processing of interstellar materials.
- Carbonaceous CI chondrites offer insights into primitive solar system bodies but require detailed study of their alteration processes.
- Post-accretion alteration in meteorites, particularly the formation of carbonates, is not fully understood.
Purpose of the Study:
- To investigate the timing of aqueous alteration in CI chondrites.
- To constrain the timescale of reactions between anhydrous materials and fluids on meteorite parent bodies.
- To establish the role of aqueous alteration in the early chemical evolution of the solar system.
Main Methods:
- Measurement of excess 53Cr (a product of short-lived 53Mn decay) in carbonate fragments from CI chondrites Orgueil and Ivuna.
- Radiometric dating using the 53Mn-53Cr system.
Main Results:
- Significant excess 53Cr was detected in the carbonate fragments.
- Aqueous alteration on small protoplanetary bodies began less than 20 million years after the formation of the oldest solar-nebula condensates.
- This timescale is considerably shorter than previously inferred limits.
Conclusions:
- Aqueous alteration was a very early process in the solar system's history.
- The early onset of aqueous alteration significantly impacted the chemical evolution of protoplanetary bodies.
- These findings refine the chronology of events in the early solar system.