Halloween special VIII: The Great Dying

“Out of the Aeons” is a short story by H. P. Lovecraft and Hazel Heald. The story introduces the powerful Ghatanothoa, a Great Old One and the first-born of Cthulhu, brought to Earth from the planet Yuggoth by the Mi-go, an anciente alien race, who built a colossal fortress atop the Mount Yaddith-Gho, and sealed Ghatanothoa inside the mountain. Those who worship this entity hold the god responsible for earthquaques and other natural disasters. Like Groth himself, Ghatanothoa is the harbinger of death.

The fossil record indicates that more than 95% of all species that ever lived are now extinct. Occasionally, extinction events reach a global scale with many species of all ecological types dying out in a near geological instant. These mass extinctions were originally identified in the marine fossil record and have been interpreted as a result of catastrophic events or major environmental changes that occurred too rapidly for organisms to adapt.

Global paleogeographic map for the Permian-Triassic transition showing the location of the Siberian Traps Large Igneous Province. From Vajda et al., 2019

During the last 540 million years five mass extinction events shaped the history of the Earth. The end-Permian extinction (PTB) is the most severe biotic crisis in the fossil record, with as much as 95% of the marine animal species and a similarly high proportion of terrestrial plants and animals going extinct . This great crisis occurred 252 million years ago (Ma), and is linked to the emplacement of the large igneous province of the Siberian Traps. A new study published early this month in the journal Nature Geoscience is the first to conclusively reconstruct the entire cascade of events that lead to the PTB mass extinction.

The team lead by Hana Jurikova used the boron isotope of well preserved shells of brachiopods and paired with carbon and oxygen isotope data, generating a new record of ocean pH for the Permian/Triassic boundary. These findings indicate that the PTB mass extinction was triggered by a multimillennial-scale voluminous injection of carbon to the atmosphere by the emplacement of Siberian Traps sill intrusions. Massive volcanic eruptions with lava flows, released large quantities of sulphur dioxide, carbon dioxide, thermogenic methane and large amounts of HF, HCl, halocarbons and toxic aromatics and heavy metals into the atmosphere. The CO2 greenhouse effect resulted in strong heating and acidification of the surface ocean, which prompted the initial disappearance of all reef-building taxa. Acid rain likely had an impact on freshwater ecosystems and may have triggered forest dieback. 

 

References:

Hana Jurikova et al, Permian–Triassic mass extinction pulses driven by major marine carbon cycle perturbations, Nature Geoscience (2020). DOI: 10.1038/s41561-020-00646-4

V. Vajda et al. (2020), End-Permian (252Mya) deforestation, wildfires and flooding—An ancient biotic crisis with lessons for the present, Earth and Planetary Science Letters 529 (2020) 115875 https://doi.org/10.1016/j.epsl.2019.115875

H. P. Lovecraft & Hazel Heald, “Out of the Aeons”, Weird Tales magazine, 1935

 

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