Evolution of the parent body of enstatite (EL) chondrites

Chondrites stem from undifferentiated asteroidal parent bodies that nevertheless experienced a certain degree of metamorphism after their formation in the early solar system. Maximum temperatures depend mainly on time and abundance main heating source, which is short-lived 26Al (half life 720 000 yr). Enstatite chondrites formed under reducing conditions include many strongly metamorphosed members petrologic type 6. We model thermal evolution body low metal enstatite chondrite class (EL). The takes into account accretion, heating, sintering compaction by hot pressing initially porous material, temperature dependent heat conductivity, insulation effects remaining regolith layer. A fit key parameters comprising time, radius, porosity achieved fitting histories EL6 (LON 94100, Neuschwanstein, Khairpur, Blithfield, Daniel’s Kuil) constrained I–Xe Ar–Ar ages respective closure temperatures. Viable fits are obtained for with 120–210 km c. 1.8–2.1 Ma Ca,Al rich inclusions (CAIs), an initial 30%, relatively independent disk Optimised models formation-times >1.95 CAIs imply central core below incipient plagioclase silicate melting. Thermal different indistinguishable so burial depths. While exact layering depth somewhat (c. 12–20 km), thickness layer all five <1 km. Hence, origin quite small fragment possible, particular as most excavation inferred cosmic ray exposure data compatible separation metre sized meteoroids Apollo asteroid 33 ago.