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Paper: Nebula Evolution of Thermally Processed Solids: Reconciling Models and Meteorites
Volume: 341, Chondrites and the Protoplanetary Disk
Page: 732
Authors: Cuzzi, J.N.; Ciesla, F.J.; Petaev, M.I.; Krot, A.N.; Scott, E.R.D.; Weidenschilling, S.J.
Abstract: We relate current protoplanetary nebula process models to the observed properties of chondrites and their individual constituents. Important nebula properties and processes that affect the evolution of small solid particles include the nebula temperature and pressure, the generally inward radial drift of particles under gas drag, and nebula gas turbulence. We review these nebula properties and describe how they affect particle evolution, emphasizing the primary accretion stage whereby the first primitive meteorite parent bodies are accumulated. We then turn to chondrite properties and discuss how they constrain the models. We treat physical properties (chondrule and refractory inclusion size distributions, fine-grained and coarse-grained accretionary rims, coarse-grained igneous rims), chemical and mineralogical properties (Wark-Lovering rims, redox state, and elemental fractionations), and isotopic compositions (primarily oxygen). We note how currently inferred accretion and melting ages of asteroidal bodies seem to imply that primary accretion of existing 100-km-sized objects was delayed by 1 Myr or more relative to Ca,Al-rich inclusions, and sketch scenarios for primary accretion in a temporally evolving protoplanetary nebula which allows for this hiatus. We advance a new perspective on explaining non-equilibrium mineralogy in terms of evolutionary timescales for small particles across nebula radial thermal gradients, which should be testable using meteoritical data, and present a specific application to Wark-Lovering rims.

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