Cerium anomalies and iodine track nonuniform paleoredox conditions during the Aptian Oceanic Anoxic Event 1a
Abstract The Early Aptian Oceanic Anoxic Event 1a (OAE 1a) marks a period of global marine anoxia linked to volcanic activity and climate changes during the Cretaceous. This study analyzes a ~ 40-m-thick Lower Aptian succession from the Kazhdumi Intrashelf Basin, Iran, using I/(Ca + Mg) ratios, Ce a...
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| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2025-07-01
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| Series: | Scientific Reports |
| Online Access: | https://doi.org/10.1038/s41598-025-09471-4 |
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| Summary: | Abstract The Early Aptian Oceanic Anoxic Event 1a (OAE 1a) marks a period of global marine anoxia linked to volcanic activity and climate changes during the Cretaceous. This study analyzes a ~ 40-m-thick Lower Aptian succession from the Kazhdumi Intrashelf Basin, Iran, using I/(Ca + Mg) ratios, Ce anomalies, trace elements, δ¹³C, and REY parameters. Results reveal persistent suboxic to anoxic bottom-water conditions, with increased oxygenation in segments C3 and upper C5 + C6, driven by weathering and sea-level changes. Minimal diagenetic overprinting is indicated by C-isotope trends and low Mn/Sr ratios. The Kazhdumi Basin serves as a high-resolution archive of redox evolution during OAE 1a, emphasizing the utility of I/(Ca + Mg) and Ce anomalies as proxies in ancient carbonates. |
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| ISSN: | 2045-2322 |