Permian Marine Extinction Linked to Volcanism-Induced Lack of Oxygen
A new study published in Chemical Geology provides further evidence linking the Permian mass extinction to significant volcanic activity that resulted in a lack of oxygen in the oceans. The Permian extinction, known as the Great Dying, is considered the largest mass extinction event in Earth’s history, wiping out more than 95% of all life on the planet. The cause of this catastrophic event has long been debated, with theories ranging from a large asteroid impact to extensive volcanic eruptions.
The latest research conducted by Yu Wang of Nanjing University and his team focused on sediment samples obtained from Zhigao Quarry in China. The scientists discovered an anomaly in mercury levels, which were associated with an increase in carbon isotopes. This carbon-13 isotope excursion suggests massive releases of carbon into the atmosphere, most likely due to volcanic eruptions. It is known that volcanism is a significant source of mercury in nature.
The carbon releases coincide with the known volcanic activity of the Emeishan Traps, Sichuan—a region characterized by vast areas of flood basalts that created a large igneous province. These volcanic events contributed to the release of carbon dioxide into the atmosphere, potentially leading to global warming and ocean acidification.
The sediment samples also revealed spikes in trace elements like molybdenum, uranium, and vanadium, indicating periods of anoxia when the oceans were lacking dissolved oxygen. The lower ratios of elements such as cadmium and molybdenum suggest weakened upwelling of cold, nutrient-rich waters. Additionally, a decline in calcareous algae and fusulinacean foraminifera in the samples points towards marine anoxia and increased stratification of the water column. These conditions would have created oxygen minimum zones, making it extremely difficult for marine organisms to survive.
The researchers propose a three-step model to explain how volcanic activity led to the biotic crisis that caused the Permian mass extinction. During stage 1, the study site, which was part of a carbonate platform, experienced healthy marine life thriving in an oxygen-rich shallow marine environment. However, in stage 2, the onset of volcanic activity and the release of greenhouse gases led to a rise in global temperatures and sea levels. This, combined with regional subsidence, caused increased stratification of the water column and marine anoxia. Oxygen levels decreased as warmer waters reduced oxygen solubility, making it challenging for marine organisms to survive.
In the final stage, volcanism subsided, and the oceans returned to shallower conditions. The circulation of oxygen-rich waters and the transport of organic matter from land to the ocean revitalized the marine ecosystem, allowing organisms to recover and evolve into new ecological niches.
The study highlights the importance of understanding the role of volcanism in shaping the Earth’s ecosystems and the potential threats it poses to marine life. The research team suggests that we are currently experiencing a sixth mass extinction event, emphasizing the need to further investigate the impact of volcanism on our marine realm. By gaining a better understanding of the past, we may be able to mitigate the effects of future environmental crises.
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1. Source: Coherent Market Insights, Public sources, Desk research
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