Climate changes are known to have been a key regulator of the biodiversity in Earth's history. However, the dry-humid degrees and alternating patterns throughout the Phanerozoic remain largely unconstrained. In this study, we report high contents (2.4 ± 3.8 mg N kg⁻¹) and ¹⁷O anomalies (11.0 ± 7.4‰) of nitrate (NO₃⁻) in the early Cambrian black shale from South China, likely caused by atmospheric NO₃⁻ intrusion under dry climates that followed tectonic uplift. By developing new methods to quantify aridity indices (AI, 0.06 ± 0.08) in combination with observational data with paleoclimate models, we reconstructed the historical AI variations. Our analyses revealed three significant dry-to-humid transitions which include Cambrian-Ordovician to Silurian-Permian, Permian-Triassic boundary to middle Triassic-early Jurassic, and Jurassic-Paleogene to Neogene. This study quantitatively unlocked the Phanerozoic climate changes in South China, offering important evidence for understanding the co-evolution of ecological and climatic systems in Earth's history.

中文翻译：

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华南显生代干旱和湿度振荡的沉积 17O-硝酸盐证据


众所周知，气候变化一直是地球历史上生物多样性的关键调节器。然而，整个显生代的干湿程度和交替模式在很大程度上仍然不受限制。在这项研究中，我们报道了华南寒武世早期黑色页岩中硝酸盐 （NO₃⁻） 的高含量 （2.4 ± 3.8 mg N ^kg-1） 和 ¹⁷个 O 异常 （11.0 ± 7.4‰），这可能是由构造隆起后干燥气候下的大气 NO₃⁻ 侵入引起的。通过开发量化干旱指数 （AI， 0.06 ± 0.08） 的新方法，结合古气候模型的观测数据，我们重建了历史上的 AI 变化。我们的分析揭示了三个重要的干湿转变，包括寒武纪-奥陶纪到志留纪-二叠纪、二叠纪-三叠纪边界到中三叠世-早侏罗世，以及侏罗纪-古近纪到新近纪。这项研究定量地揭示了华南地区的显生代气候变化，为理解地球历史上生态和气候系统的共同演化提供了重要证据。