High spatial resolution ion microprobe measurements refine chronology of carbonate formation in Orgueil
High spatial resolution ion microprobe measurements refine chronology of carbonate formation in Orgueil
复制标题
高空间分辨率离子微探针测量完善了奥盖尔碳酸盐形成的年代学
DOI：
10.1111/j.1945-5100.2007.tb00576.x
复制
发表时间：
2007
影响因子：
2.2
通讯作者：
G. Lugmair
中科院分区：
文献类型：
--
作者：
P. Hoppe;D. Macdougall;G. Lugmair
摘要-水对陨石母体的活动是由碳酸盐的存在。对来自奥尔盖尔陨石的九个单独的碳酸盐颗粒（四个白云岩，五个布雷纳岩）进行的高空间分辨率离子微探针分析显示，所有颗粒中53 Cr过量与Mn/Cr比之间存在线性相关性，表明放射性53 Mn的原位衰变（半衰期370万年）。定义明确的等时线似乎具有年代意义。如果是这样的话，那么碳酸盐形成时间的53 Mn/55 Mn比值在2.1 × 10 − 6到4.7 × 10−6之间，计算出的绝对年龄在4561 Ma到4565 Ma之间（系统不确定度为±2 Ma）。白云岩往往比布吕纳岩形成得稍早。我们的数据表明，在太阳系形成后的2000 - 400万年间，奥盖尔母体上广泛的水活动，最有可能是放射性26 Al和60 Fe衰变产生的冲击加热和潜热的结果。
Abstract— Aqueous activity on meteorite parent bodies is indicated by the presence of carbonates. High spatial resolution ion microprobe analyses of nine individual carbonate grains (four dolomites, five breunnerites) from the Orgueil meteorite reveal linear correlations between 53Cr excesses and Mn/Cr ratios in all grains, indicative of in situ decay of radioactive 53Mn (half‐life 3.7 million years). The well‐defined isochrons appear to have chronological significance. If this is the case, then 53Mn/55Mn ratios between 2.1 and 4.7 × 10−6 are inferred for the time of carbonate formation and absolute ages of between 4561 and 4565 Ma are calculated (systematic uncertainty of ±2 Ma). Dolomites tend to have formed slightly earlier than the breunnerites. Our data imply extensive aqueous activity on the Orgueil parent body over a period of several million years, starting ∼3–4 Myr after formation of the solar system, that most likely was the result of impact heating and latent heat from the decay of radioactive 26Al and 60Fe.