Impact history of the HED parent body(ies) clarified by new 40 Ar/ 39 Ar analyses of four HED meteorites and one anomalous basaltic achondrite

We investigate the thermal/impact histories of four HED meteorites: one cumulate eucrite (Lake Carnegie) two brecciated basaltic eucrites (Camel Donga, Millbillillie), one howardite (Old Homestead 003) and an anomalous basaltic achondrite (Deakin 010). We have measured eight convincing new 40Ar/39Ar ages for three HED meteorites. Laser incremental 40Ar/39Ar analyses of carefully separated small grains (<250μm) of plagioclase, pyroxene, matrix and melt rock from these meteorites yielded well-defined plateau and/or isochron ages for two samples of Lake Carnegie, four samples of Millbillillie and two samples of Camel Donga.