The mid‐Proterozoic (ca. 1.8–0.8 Ga) witnessed a period of stable carbon cycling and long stasis in eukaryotic evolution, which was commonly ascribed to the persistently low oxygen levels in the atmosphere‐ocean system. Recently, several pulsed marine oxygenations were identified from different continents, and presumed to have facilitated the short‐term diversification of eukaryotes in the early Mesoproterozoic Era. To test this hypothesis, an integrated study of iodine species [I/ (Ca + Mg)], paired carbon isotopes (δ¹³C_carb and δ¹³C_org), and elemental abundances was conducted on the fossil‐bearing Tuanshanzi Formation (∼1.64–1.63 Ga), North China. The near‐zero I/(Ca + Mg) ratios (0.00 ± 0.01 μmol/mol) coupled with low δ¹³C_org (−30.2 ± 1.4‰) in the strata below the fossil‐bearing interval suggests anoxic conditions in shallow seawater. An increase of I/ (Ca + Mg) up to ∼1.54 μmol/mol coupled with a ∼2‰ negative shift in δ¹³C_carb and a ∼11‰ positive excursion in δ¹³C_org in the fossil‐bearing interval point to an increased oxygen concentration. Above the fossil‐bearing interval, I/ (Ca + Mg) decrease to <0.5 μmol/mol, suggesting deoxygenation and a return to anoxic to suboxic conditions. Combined with relevant data from other mid‐Proterozoic sections of North China and Australia, these data likely indicate dynamic redox conditions in the shallow seawaters of this period, with multiple pulses in oxygenation in otherwise anoxic conditions. These pulsed oxygenations may have facilitated short‐term proliferation and diversification of early eukaryotes in shallow seawaters, but the overall low oxygen levels have impeded their continuous development and the rise to ecological dominance until late Neoproterozoic.

中文翻译：

---

古元古代末期的脉冲氧化作用：来自华北川岭沟和团山子组之间过渡的证据

中元古代（约1.8-0.8 Ga）见证了一个稳定的碳循环和真核演化的长期停滞期，这通常归因于大气-海洋系统中持续的低氧水平。最近，在不同的大陆上发现了几种脉冲海洋氧合作用，并推测它们促进了中元古代时代真核生物的短期多样化。为了检验这一假设，碘物质的综合研究[I /（CA + Mg）的]，成对的碳同位素（δ ¹³ C ^_{碳水化合物}和δ ¹³ C ^_有机），并在华北的含化石的团山子组（〜1.64〜1.63 Ga）上进行了元素丰度。接近零I /（CA + Mg）的比率（0.00±0.01微摩尔/摩尔）加上低δ ¹³ Ç_有机化石轴承间隔下面的地层（-30.2±1.4‰）表明在浅海水缺氧条件。的我的增加/（CA + Mg）的高达~1.54微摩尔/摩尔加上δ一个〜2‰负偏移¹³ Ç_{碳水化合物}和〜11‰正偏移中δ ¹³ C ^_有机在含化石的时间间隔中，表明氧气浓度增加。在高于化石的时间间隔内，I /（Ca + Mg）降低至<0.5μmol/ mol，这表明脱氧并恢复为缺氧至亚缺氧状态。结合来自华北和澳大利亚其他元古代中期剖面的相关数据，这些数据可能表明该时期浅海水中的动态氧化还原条件，而在其他缺氧条件下充氧有多个脉冲。这些脉冲式的氧合作用可能促进了浅海海水中早期真核生物的短期增殖和多样化，但是总体低氧水平阻碍了它们的持续发展和生态优势地位的发展，直到新元古代晚期。