南京大学李伟强教授课题组经过不懈努力，发现了中太古宙海洋中氧绿洲的扩大。该研究于2025年2月10日发表在《地质学》杂志上。

氧气光合作用在地球表面游离氧（O₂）的积累中起着至关重要的作用，但关于其进化时间线仍存在疑问。南非中太古宙蓬戈拉超组富含锰（Mn）的沉积岩被认为是海洋中依赖氧气的锰（II）氧化和光合作用产生氧气的最早证据之一。然而，作为一套独特的岩石，蓬戈拉地区O₂的证据是否具有全球意义仍然存在不确定性。

研究组报道了中国南方另一个中太古宙富锰铁地层，其历史可追溯到约2.88−2.80 Ga。甸子河铁地层的锰富集（MnO高达7.08 wt%，Fe/Mn比降至5.1）与负δ⁵⁶Fe值（-0.21至-1.33‰；平均=-0.91‰）呈正相关。这种模式需要含氧海水（即O₂>10μM）至少到达海底，不仅实现Fe（II）和Mn（II）的氧化，还实现Fe（Mn）羟基氧化物的保存，直到沉积后的改造。根据在中国的发现以及南非富锰铁地层的分布，研究组认为，在中太古宙已经存在由蓝藻O₂生产驱动的全球氧气绿洲分布。

附：英文原文

Title: Proliferation of oxygen oases in Mesoarchean oceans

Author: Hui Ye, Chang-Zhi Wu, Xiao-Lei Wang, Tao Yang, Yue Guan, Xiuqing Yang, Weiduo Hao, Kurt O. Konhauser, Weiqiang Li

Issue&Volume: 2025-02-10

Abstract: Oxygenic photosynthesis played an essential role in the accumulation of free oxygen (O2) at Earth’s surface, but questions persist regarding its evolutionary timeline. Manganese (Mn)-rich sedimentary rocks from the Mesoarchean Pongola Supergroup in South Africa have been invoked among the earliest evidence for O2-dependent Mn(II) oxidation and thus photosynthetic O2 production in oceans. However, as a singular suite of rocks, uncertainties persist about whether the evidence for O2 in the Pongola region has global implications. Here we report on another Mesoarchean Mn-rich iron formation in South China, dating back to ca. 2.882.80 Ga. The Dianzihe iron formation exhibits a positive correlation between Mn enrichment (MnO up to 7.08 wt%, Fe/Mn ratio down to 5.1) and negative δ56Fe values (0.21 to 1.33‰; average = 0.91‰). This pattern requires oxygenated seawater (i.e., O2 > 10 μM) at least to the seafloor, allowing not only for the oxidation of Fe(II) and Mn(II) but also for the preservation of Fe(Mn) oxyhydroxides until post-depositional modifications. Based on our findings in China alongside the distribution of Mn-rich iron formations in South Africa, we posit that a global distribution of oxygen oases, driven by cyanobacterial O2 production, already existed in the Mesoarchean.

DOI: 10.1130/G52607.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G52607.1/651999/Proliferation-of-oxygen-oases-in-MesoarcheanredirectedFrom=fulltext