Non-equilibrium condensation of the first Solar System solids

Area of Science:

• Planetary Science
• Cosmochemistry
• Astrophysics

Background:

• Chondrites, primitive meteorites, contain minerals formed during solar nebula assembly.
• Their precursor condensation conditions are unclear due to subsequent reprocessing.
• Existing equilibrium models fail to explain the three main chondrite classes (enstatite, ordinary, carbonaceous).

Purpose of the Study:

• To test the hypothesis that chondrite precursors formed via kinetic non-equilibrium condensation.
• To explain the emergence of distinct chondrite mineralogical classes.
• To offer an alternative to large-scale oxidation variations for explaining chondrite diversity.

Main Methods:

• Utilized a new time-dependent condensation model.
• Simulated varying cooling rates and pressures.
• Projected predicted mineralogical types into a Urey-Craig diagram.

Main Results:

• Demonstrated that varying cooling rate and pressure produce only three types of mineralogies.
• Showed that departure from equilibrium leads to increasingly oxidized and hydrous mineralogies.
• Predicted mineralogical types closely match the redox states of enstatite, ordinary, and carbonaceous chondrites.

Conclusions:

• Chondrite mineralogical diversity may partly reflect local condensation kinetics.
• Kinetic non-equilibrium condensation offers an alternative explanation for chondrite classification.
• This study provides insights into the formation conditions of early solar system materials.