Meteorites that produce K-feldspar-rich ejecta blankets correspond to mass extinctions.

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1144/jgs2021-055. This is version 4 of this Preprint.

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Authors

Matt Pankhurst, Christopher Stevenson , Beverley Claire Coldwell 

Abstract

Meteorite impacts load the atmosphere with dust and cover the Earth‘s surface with debris. They have long been debated as a trigger of mass extinctions through Earth‘s history. Impact winters generally last <100 years, whereas ejecta blankets persist for 10^3-10^5 years. Here we show that only meteorite impacts that emplaced ejecta blankets rich in K-feldspar (Kfs) correlate to Earth system crises (n=11, p<0.000005). Kfs is a powerful ice-nucleating aerosol yet is normally rare in atmospheric dust mineralogy. Ice nucleation plays an important role in cloud microphysics, which modulates global albedo. A conceptual model is proposed whereby the anomalous prevalence of Kfs is posited to have two key effects on cloud dynamics: 1) reducing the average albedo of mixed-phase cloud, which effected a hotter climate; 2) weakening of the cloud albedo feedback, which increased climate sensitivity. These mechanisms offer an explanation as to why this otherwise benign mineral is correlated so strongly with mass extinction events: every K-feldspar-rich ejecta blanket corresponds to a severe extinction episode over the past 600 Myr. This model may also explain why many kill mechanisms only variably correlate with extinction events through geological time: they coincide with these rare periods of climate destabilization by atmospheric Kfs.

DOI

https://doi.org/10.31223/X5RK6C

Subjects

Applied Statistics, Atmospheric Sciences, Earth Sciences, Geology, Other Planetary Sciences, Paleontology, Physical Sciences and Mathematics

Keywords

Meteorite impact; K-feldspar; mass extinction; ice nucleation; cloud

Dates

Published: 2021-05-24 11:00

Last Updated: 2021-12-06 22:26

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License

CC BY Attribution 4.0 International

Additional Metadata

Conflict of interest statement:
The authors declare no conflict of interest

Data Availability (Reason not available):
All data underpinning the analysis in this MS is already in the published literature. Supp Material also will be made available.

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