Chemical zoning in pristine objects of chondrites as archive of the thermal and redox history in the early solar nebula and planetesimals

在陨石中已经发现了一些原始矿物，人们认为这些陨石是在太阳系形成的最初数百万年里，由原行星吸积盘中的气体凝聚而成的。详细的矿物化学和任何保存下来的化学分区为它们的热历史提供了一个独特的档案。我们计划识别各种热事件(例如太阳星云中的瞬变加热事件和宿主陨石母体上的热变质作用)，并通过扩散模拟的方法从这些原始矿物中主要、次要和微量元素的分带推断相关的峰值温度和冷却速度。由于最近公布的一组准确的扩散数据、最近建立的建模技术以及给定矿物中不同元素对不同温度范围的敏感性，现在可以详细说明热事件的复杂序列。后者与矿物中各种元素的流动性有很大的不同。得出的热历史将极大地提高我们对太阳星云以及类似小行星天体的物理条件的理解。

A number of pristine minerals have been identified in meteorites that are thought to be formed by condensation from gas in the protoplanetary accretion disk during the first few million years of the solar system. The detailed mineral chemistry and any chemical zoning preserved provide a unique archive of their thermal history. We plan to identify the various thermal events (e.g. transient heating events in the solar nebula and the thermal metamorphism on the parent body of the host meteorite) and infer the associated peak temperatures and cooling rates from the zonings of major, minor, and trace elements in these pristine minerals by means of diffusion modeling. The elaboration of the complex sequence of thermal events is now possible due to the recently published set of accurate diffusion data, recently established modeling techniques, and finally, the sensitivity of different elements in a given mineral to different temperature ranges. The latter aspect is related to the strongly different mobility of various elements within a mineral. The derived thermal histories would significantly improve our understanding of the physical conditions in the solar nebula as wells as in small planet like objects.