加拿大圣弗朗西斯泽维尔大学J.B. Murphy团队研究了新元古代冰期的大陆风化。相关论文于2025年2月25日发表在《地质学》杂志上。

新元古代雪球地球事件反映了全球寒冷的条件，被认为刺激了地球化学循环的变化和行星生物的反应。

研究组分析了这些事件对沉积物动力学的影响，重点研究了苏格兰和爱尔兰Dalradian超群内的碎屑锆石记录。利用U-Pb碎屑锆石年龄，通过自举方差度量分析了整个地层中沉积物物源的变化。碎屑锆石负载的方差系数在地层上呈一级上升趋势，在冰川成因层发生了显著变化。与较低的冰川前地层水平相比，方差增加的点与较老碎屑的输入一致，表明与湿基冰川活动有关的侵蚀和下切加剧，以及冰川后沉积物的重新分布。

平均碎屑锆石表观密度也会随着地层而变化，这对铀从大陆到海洋的循环具有影响。虽然早期埃迪卡拉纪页岩地球化学意味着冰川期后的海洋氧化，但冰川成因层中富铀碎屑锆石的比例增加表明，大陆风化的改变也从根本上促成了新元古代的地球化学变化。

附：英文原文

Title: The Neoproterozoic glacial broom

Author: C.L. Kirkland, R.A. Strachan, D.B. Archibald, J.B. Murphy

Issue&Volume: 2025-02-25

Abstract: Neoproterozoic snowball Earth events reflect globally frigid conditions thought to have stimulated changes in geochemical cycling with planetary biotic response. We investigated the impact of these events on sediment dynamics, focusing on the detrital zircon record within the Dalradian Supergroup of Scotland and Ireland. Utilizing U-Pb detrital zircon ages, we analyzed changes in sediment provenance throughout the stratigraphy via bootstrapped variance metrics. The coefficient of variance for the detrital zircon load exhibits a first-order increase stratigraphically upward, with marked changes at glaciogenic layers. Points of increased variance align with inputs of older detritus compared to lower, preglacial stratigraphic levels, suggesting intensified erosion and downcutting linked to wet-based glacial activity, with postglacial sediment redistribution. Average detrital zircon apparent density also changes through the stratigraphy, with implications for uranium cycling from the continents into the oceans. While early Ediacaran shale geochemistry implies postglacial oceanic oxygenation, loss of proportionally more uranium-rich detrital zircon across glaciogenic layers suggests that modification to continental weathering also fundamentally contributed to Neoproterozoic geochemical shifts.

DOI: 10.1130/G52887.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G52887.1/652370/The-Neoproterozoic-glacial-broom