The End-Guadalupian Mass Extinction, Pyrite, and Sulfur Isotopes – #365papers – 2017 – 2

#365papers – January 2, 2017

Wei, Wei, Qiu, Song, Shi, 2016, Redox conditions across the G-L boundary in South China: Evidence from pyrite morphology and sulfur isotopic compositions: Chemical Geology, v. 440, p. 1-14.

What’s it about?

This paper presents evidence that marine anoxia (lack of oxygen in ocean water) may be the cause of the end-Guadalupian (middle Permian) mass extinction, using the appearance of pyrite (a reduced-iron mineral, FeS2), the shape and structure of pyrite, and isotopic values of sulfur to show this.

Why does it matter?

There is a lot of interest in what can cause world-wide extinctions. Some well-known extinctions, like the “K-T boundary” when dinosaurs went extinct are known to be caused by impacts of extraterrestrial objects with the Earth. However, most mass extinctions have origins on the Earth itself, and marine anoxia is often the cause. These new observations allow us to better understand how such extinctions work.

Why did I read this?

I read this because I am interested in using isotopes to evaluate environmental change. I am particularly interested in pyrite and pyrite framboids that are discussed in this paper because they are indicative of a reducing (non-oxygenated) environment, which one-upon-a-time I was really, really interested in because uranium is not soluble under such conditions. In a past life (grad school) I was really interested in uranium mobility because it can catalyze reactions that dissolve vertebrate bones.

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