Hf-W chronology of early solar system processes

从太阳系中第一个固体形成到星子形成的时间间隔只持续了几百万年（Myr）。在这一短暂的时间间隔内发生的物理和化学过程为早期太阳系行星的起源和演化创造了条件。为了重建这些过程，必须获得非常精确的年龄，以确定真实的事件的日期或提供有关过程速率的信息。这种高精度的年龄可以用短寿命的同位素获得，例如182 Hf，它衰变到182 W（t1/2 ~9 Myr）。由于Hf和W的地球化学性质，衰变系统非常适合于在任何尺度上限制金属形成或硅酸盐金属平衡的时间。该项目的一个主要目标是获得不同球粒陨石群以及中球粒陨石和钯陨石形成的高精度年龄（± 100万年或更高）。因为现在已经确定陨石不是太阳系中最古老的天体，它们在太阳系化学和矿物学演化中的作用变得不那么清楚。因此，我们计划为球粒形成过程构建一个绝对时间框架，并将其与太阳系前1000万年期间发生的其他分化过程联系起来。

The time interval from formation of the first solids in the solar system to the formation of planetesimals lasted only a few million years (Myr). The physical and chemical processes that occurred during this brief interval set the conditions for the origin and evolution of the planets in the early solar system. To reconstruct these processes, it is essential to obtain very precise ages that date real events or that provide information on the rates of processes. Such high precision ages can be obtained with shortlived isotopes, such as 182Hf, which decays to 182W (t1/2 ~9 Myr). Due to the geochemical properties of Hf and W, the decay system is ideally suited to constraining the time of metal formation or silicatemetal equilibration at any scale. A major goal of this project will be to obtain highly precise ages (±1 Myr or better) for the formation of different chondrite groups as well as mesosiderites and pallasites. Because it is now well established that chondrites are not the oldest objects in the solar system, their role in the chemical and mineralogical evolution of the solar system has become less clear. Therefore, we plan to construct an absolute time frame for the chondrule-forming process(es) and relate this to other differentiation processes that occurred during the first 10 Myr of our solar system.