美国高校宇航探索协会T.J. Barrett及其团队成员，对一个横跨加拿大萨德伯里盆地剖面的冲击沉积物进行了氯同位素测定，其结果揭示了系统的同位素分馏。2024年11月13日，国际知名学术期刊《地质学》发表了这一成果。

据了解，大规模撞击会对挥发性系统（例如氢和氯）产生重大影响，因为撞击前后的压力和温度，会造成挥发性物质的迅速损失和同位素分馏。

研究人员对加拿大萨德伯里撞击构造的10个样品磷灰石的，Cl同位素组成和[Cl]和[H₂O]进行了测定。下部诺利岩中的[Cl]值高和δ³⁷Cl值不变被归因于下盘同化作用，与最近的Zn和Pb数据一致。萨德伯里火成岩杂岩顶部的花岗闪长岩，显示了Cl的损失和分馏（高达+6.26‰），表明在高气压状态下发生了脱气，高[H₂O]进一步缓冲同位素分馏作用。

类似的撞击发生在干燥、无空气的天体上，比如月球，可能允许更大量的同位素分馏，支持极度分馏的月球物质作为大规模撞击衍生脱气假说的证据。Onaping组磷灰石的适度分馏（高达+8.15‰）和形态，明显可以用撞击后的热液蚀变来解释。

附：英文原文

Title: A chlorine isotope transect across Sudbury Basin (Canada) impact deposits reveals systematic isotope fractionation

Author: T.J. Barrett, K. Nagashima, G.R. Huss, J.W. Boyce, K.L. Robinson, D.A. Kring

Issue&Volume: 2024-11-13

Abstract: Large-scale impacts are known to have a significant effect on volatile systematics (e.g., hydrogen and chlorine) owing to syn- and post-shock pressures and temperatures allowing for ready volatile loss and isotopic fractionation. We determined the Cl isotopic composition and [Cl] and [H₂O] for apatite from 10 samples of the Sudbury impact structure in Canada. The high [Cl] and invariant δ³⁷Cl values in the lower norite are attributed to footwall assimilation in agreement with recent Zn and Pb data. The granophyre, the top of the Sudbury Igneous Complex, displays loss and fractionation of Cl (up to +6.26‰) indicative of degassing under a high gas pressure regime with high [H₂O] further buffering isotope fractionation. Similar impacts on dry, airless bodies such as the Moon may have permitted greater amounts of isotopic fractionation, supporting extremely fractionated lunar materials as evidence for the large-scale impact-derived degassing hypothesis. The modest fractionation (up to +8.15‰) and morphologically distinct apatite of the Onaping Formation can be explained by post-impact hydrothermal alteration.

DOI: 10.1130/G52624.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G52624.1/650063/A-chlorine-isotope-transect-across-Sudbury-Basin