科廷大学M. Daniík小组宣布他们研究出白云母对撞击变质作用的微观结构及地球化学响应。该研究于2025年12月4日发表于国际一流学术期刊《地质学》杂志上。

该课题组提出了来自澳大利亚西部Yarrabubba结构的激波伟晶岩的新特征。受冲击的白云母形成了扭结带，这些扭结带经过了化学修饰，增加了绿鳞石的含量，这被解释为与撞击事件同时发生。未受应变改造且未发生化学变化的原生白云母原位铷-锶测年结果（2463±25 Ma）与⁴⁰Ar/³⁹Ar测年数据（约2464 Ma概率峰值），与伟晶岩锆石铀-铅结晶年龄（2440±16 Ma）基本吻合。相反，高应变富绿鳞石条带的白云母⁴⁰Ar/³⁹Ar测年呈现出复杂的年龄谱系，其约2266 Ma的概率峰值与亚拉布巴撞击年龄高度重合。研究结果表明，白云母作为一种主要的成矿矿物，在撞击变质过程中保留了独特的微观结构和地球化学特征，定向⁴⁰Ar/³⁹Ar分析可以为撞击年龄提供可靠的上限。

据悉，火流星的撞击会对地球产生深远的影响，引发生物地球化学的变化，这些变化可能会消灭、启动甚至使生命多样化。它们，识别和确定撞击结构的年代，特别是在古代岩石中，可以为理解撞击在地球进化中的作用提供关键的时间背景。

附：英文原文

Title: Microstructural and geochemical response of muscovite to impact metamorphism

Author: B.V. Ribeiro, V. Jakobsson, C.L. Kirkland, R.A. Spikings, A. Zametzer, W.D.A. Rickard, S. Centrella, N.E. Timms, A.J. Cavosie, M. Daniík

Issue&Volume: 2025-12-04

Abstract: Bolide impacts can have profound effects on Earth, causing biogeochemical changes that may obliterate, initiate, or even diversify life. Thus, identifying and dating impact structures, especially in ancient rocks, can provide crucial temporal context for understanding the role of impacts in Earth’s evolution. We present novel characterization of muscovite from shocked pegmatites of the Yarrabubba structure in Western Australia. Shocked muscovite developed kink bands that underwent chemical modification, increasing the celadonite content, interpreted to be coeval with the impact event. In situ RbSr (2463 ± 25 Ma) and 40Ar/39Ar dates (ca. 2464 Ma; probability peak) from low-strain, chemically unmodified muscovite overlap with zircon UPb dates (2440 ± 16 Ma) of pegmatite crystallization. Conversely, in situ 40Ar/39Ar dates from high-strain, celadonite-enriched lamellae define a complex age spectrum with a ca. 2266 Ma probability peak, overlapping the Yarrabubba impact age. Our findings indicate that muscovite, a major crustal mineral, can retain unique microstructural and geochemical features formed during impact metamorphism, and that targeted 40Ar/39Ar analysis can provide a reliable upper limit for the impact age.

DOI: 10.1130/G53895.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G53895.1/721720/Microstructural-and-geochemical-response-of