标题： 太阳系C库中时间分布的母体吸积 显示英文标题

标题： Temporally distributed parent body accretion in the C reservoir of the solar system

摘要： 吸积过程在原行星盘中产生了多种小天体，这些天体在太阳系的多次重新排列事件中发挥了关键作用，并在行星的早期和晚期吸积中都起到了作用。 将热年代计应用于陨石可以精确测定矿物成分的形成年龄。 指示NC和C陨石之间二分法的核合成异常以及精确的母体（PB）年代学可以与热演化模型结合，以限制早期太阳系吸积和动力学过程的时间尺度。 无球粒陨石PB被认为是在早期主要在NC区域吸积的，而在C区域的晚期吸积主要产生了未分化的PB，例如CR球粒陨石PB，其形成时间甚至晚至CAIs之后4 Ma。 然而，更进化的CR相关陨石的存在表明也存在较早的吸积时间。 我们提供了建模证据，表明CR相关陨石群的母体在时间上是分布吸积的，这些陨石起源于C储层，从水蚀变球粒陨石到部分分化原始无球粒陨石不等。 所得到的PB形成时间范围从太阳系形成后不到1 Ma到约4 Ma，其中CR、Flensburg、NWA 6704和NWA 011分别为约3.7 Ma、约1.5-2.75 Ma、不到约0.6 Ma和不到约0.7 Ma。 这意味着C储层中的吸积过程早在NC储层中就开始了，并且除了未分化的C球粒陨石PB外，还产生了具有碳质成分的分化PB。 吸积时间与陨石的蚀变、变质或分化的程度呈反相关。 CI/CM、Ryugu和Tafassites PB的吸积时间分别为约3.75 Ma、约1-3 Ma和1.1 Ma，这与陨石所提示的热和蚀变条件相一致，很好地符合这一相关性。 显示英文摘要

摘要： Accretion processes in protoplanetary disks produce a diversity of small bodies that played a crucial role in multiple reshuffling events throughout the solar system and in both early and late accretion of planets. Application of thermo-chronometers to meteorites provides precise dating of the formation age of mineralogical components. Nucleosynthetic anomalies indicating a dichotomy between NC and C meteorites and precise parent body (PB) chronology can be combined with thermal evolution models to constrain the timescale of accretion and dynamical processes in the early solar system. Achondrite PBs are considered to have accreted early and mostly in the NC region, while late accretion in the C region produced mostly undifferentiated PBs, such as the CR chondrite PB that formed as late as 4 Ma after CAIs. However, presence of more evolved CR-related meteorites suggests also an earlier accretion timing. We present modeling evidence for a temporally distributed accretion of parent bodies of CR-related meteorite groups that originate from a C reservoir and range from aqueously altered chondrites to partially differentiated primitive achondrites. The PB formation times derived range from <1 Ma to ~4 Ma after solar system formation, with ~3.7 Ma, ~1.5-2.75 Ma, <~0.6 Ma, and <~0.7 Ma for CR, Flensburg, NWA 6704, and NWA 011. This implies that accretion processes in the C reservoir started as early as in the NC reservoir and produced differentiated PBs with carbonaceous compositions in addition to undifferentiated C chondritic PBs. The accretion times correlate inversely with the degree of the meteorites' alteration, metamorphism, or differentiation. Accretion times for CI/CM, Ryugu, and Tafassites PBs of ~3.75 Ma, ~1-3 Ma, and 1.1 Ma, respectively, fit well into this correlation in agreement with the thermal and alteration conditions suggested by the meteorites.