澳大利亚墨尔本大学Conor Moynihan团队报道了晚古生代陆生植物演化引起的海洋氧化与生态重构。该研究进展于2024年10月8日发表于《地质学》杂志。

据研究人员介绍，泥盆纪和密西西比纪期间海洋-大气中氧含量的急剧增加，与陆地植物的多样化联系越来越紧密，但这一事件发生的时间和程度仍不确定。

该研究使用氧化还原敏感稀土元素铈(铈异常-Ce/Ce*)为研究对象，以探讨全球分布的古生代碳酸盐岩沉积过程中的海洋氧化还原条件。研究的古生代Ce/Ce*记录表明，寒武纪、奥陶纪和志留纪海洋的O₂含量相对较低(平均值Ce/Ce*分别为0.86±0.10、0.91±0.14和0.91±0.10[±1σ])。

相比之下，短期海洋氧化事件可能发生在早泥盆世和中泥盆世(平均Ce/Ce*分别为0.80±0.07和0.58±0.14)，可能与小型陆地植物的多样化有关。“现代”Ce/Ce*值(<0.36)最早出现在晚泥盆世表明，泥盆纪和密西西比纪的海洋氧化主要阶段，与大型维管植物和第一代森林的演化有关。

尽管如此，Ce/Ce*值在此期间的显著变化表明，浅海环境容易受到氧化还原不稳定性的影响，这可能是由缺氧深水上涌引起的。这种氧化还原不稳定性可能为当代生物大灭绝，和后生动物珊瑚礁崩塌事件的机制提供证据。研究结果强调，晚泥盆世强氧条件的发展可能导致了许多古生代型生物的灭绝，促进了现代进化动物群的辐射，并建立了现代含氧海洋—大气系统。

附：英文原文

Title: Ocean oxygenation and ecological restructuring caused by the late Paleozoic evolution of land plants

Author: Jack Stacey, Malcolm W. Wallace, Ashleigh v.S. Hood, Alice M. Shuster, Hilary Corlett, Christopher P. Reed, Conor Moynihan

Issue&Volume: 2024-10-08

Abstract: The dramatic increase in ocean-atmosphere oxygen levels during the Devonian and Mississippian is increasingly linked to the diversification of land plants, yet the timing and extent of this event remain uncertain. This study uses the redox-sensitive rare earth element cerium (cerium anomaly—Ce/Ce*) to investigate ocean redox conditions during the deposition of globally distributed Paleozoic carbonate strata. Our Paleozoic Ce/Ce* record suggests that Cambrian, Ordovician, and Silurian oceans had relatively low O₂ levels (mean Ce/Ce* = 0.86 ± 0.10, 0.91 ± 0.14, and 0.91 ± 0.10 [±1σ], respectively). In contrast, short-lived ocean oxygenation events, possibly related to the diversification of small land plants, likely occurred throughout the Early and Middle Devonian (mean Ce/Ce* = 0.80 ± 0.07 and 0.58 ± 0.14, respectively). “Modern” Ce/Ce* values (<0.36) first occurred during the Late Devonian, suggesting that the main phase of Devonian and Mississippian oceanic oxygenation was related to the evolution of large vascular plants and the first forests. Despite this, the significant variability of Ce/Ce* values during this time suggests that shallow marine settings were susceptible to redox instability, possibly caused by upwelling of anoxic deep waters. This redox instability potentially provides evidence of a mechanism for contemporaneous mass extinction and metazoan reef collapse events. Development of strongly oxic conditions during the Late Devonian may have resulted in the demise of many Paleozoic-type organisms, facilitated the radiation of the modern evolutionary fauna, and established the modern oxygenated ocean-atmosphere system.

DOI: 10.1130/G52502.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G52502.1/649068/Ocean-oxygenation-and-ecological-restructuringredirectedFrom=fulltext