LETTER Age of the eucrite "Caldera" from convergence of long-lived and short-lived chronometers

-The long-lived 1475m-143Nd chronometer has been used in conjunction with the short-lived 146Sm-142Nd and 53Mn-53Cr chronometers to constrain the time of formation for the eucrite Caldera. The combination of these three chronometers has produced results that are consistent with one another and converge on a precise, high resolution age of 4537 +__ 12 Ma (within 95% confidence limits). So far this is the youngest crystallization age that has been confirmed for a noncumulate eucrite. Thus, this basaltic meteorite formed relatively late as compared to other noncumulate eucrites on a differentiated asteroidal parent body, most likely between 17 and 41 million years after the formation of the first condensates in the early Solar System. From these age constraints it is evident that Caldera either formed within a magma body on a large (>500 km) asteroid or in an extensive impact melt on the crust of its parent body.