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Flame extinguished! End-triassic mass extinction polycyclic aromatic hydrocarbons reflect more than just fire

Flame extinguished! End-triassic mass extinction polycyclic aromatic hydrocarbons reflect more than just fire
Flame extinguished! End-triassic mass extinction polycyclic aromatic hydrocarbons reflect more than just fire
Global warming induced-wildfires of the 21st century reveal the catastrophic effects that widespread biomass burning has on flora and fauna. During mass extinction events, similar wildfire episodes are considered to play an important role in driving perturbations in terrestrial ecosystems. To better evaluate the record of biomass burning and potential carbon cycle feedbacks at the end-Triassic mass extinction (~202 Ma; ETE), we investigated the relative abundances of a range of polycyclic aromatic hydrocarbons (PAHs) and the 13C values of regular isoprenoids and n-alkanes at key sections in the SW UK. These data reveal little evidence for intensive wildfire activity during the extinction event, in contrast to what has been reported further afield in European, Chinese, and Greenland ETE sections. Herein, PAHs instead reflect greater contributions from an episode of soil erosion that we attribute to Large Igneous Province (LIP)-driven acid rain, and possible distal sources of smoke, suggestive of fire elsewhere in the UK/European basins. This terrestrial ecosystem perturbation is coincident with those in the marine realm, indicating ecosystem perturbations occurred across multiple habitats throughout the latest Rhaetian in the SW UK. Additionally, this geochemical approach reveals that the precursor carbon isotope excursion (CIE) routinely used in chemostratigraphic correlations is unrelated to LIP activity, but instead results from the increased input of terrestrially derived 13C-depleted plant material. Furthermore, we find the initial CIE (commonly used to mark the extinction level, but which is now known to precede the ETE) is also unrelated to biomass burning. Collectively, these data reveal that processes other than combustion of terrestrial material are important for the terrestrial phase of the ETE in the SW UK. Similar investigations are required on other ETE sections, both those in close proximity to the LIP driving the extinction and those further afield, to more clearly determine the negative effect(s) of LIPs and their geographic extent in the terrestrial realm.
Fox, C.P.
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Whiteside, Jessica
5d9ad7aa-eba3-4ad9-9f6f-81be71b6829b
Olsen, P.E.
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Grice, K.
5727db9b-587e-4b50-94df-d4521f938c71
Fox, C.P.
2c9c4d0f-fceb-4563-9b07-c2c1e8baf6cb
Whiteside, Jessica
5d9ad7aa-eba3-4ad9-9f6f-81be71b6829b
Olsen, P.E.
7a00ffa3-3baa-4bc6-949a-f0fec2f7a594
Grice, K.
5727db9b-587e-4b50-94df-d4521f938c71

Fox, C.P., Whiteside, Jessica, Olsen, P.E. and Grice, K. (2022) Flame extinguished! End-triassic mass extinction polycyclic aromatic hydrocarbons reflect more than just fire. 30th International Meeting on Organic Geochemistry (IMOG 2021), Online. 12 - 17 Sep 2021. 2 pp . (In Press) (doi:10.3997/2214-4609.202134219).

Record type: Conference or Workshop Item (Paper)

Abstract

Global warming induced-wildfires of the 21st century reveal the catastrophic effects that widespread biomass burning has on flora and fauna. During mass extinction events, similar wildfire episodes are considered to play an important role in driving perturbations in terrestrial ecosystems. To better evaluate the record of biomass burning and potential carbon cycle feedbacks at the end-Triassic mass extinction (~202 Ma; ETE), we investigated the relative abundances of a range of polycyclic aromatic hydrocarbons (PAHs) and the 13C values of regular isoprenoids and n-alkanes at key sections in the SW UK. These data reveal little evidence for intensive wildfire activity during the extinction event, in contrast to what has been reported further afield in European, Chinese, and Greenland ETE sections. Herein, PAHs instead reflect greater contributions from an episode of soil erosion that we attribute to Large Igneous Province (LIP)-driven acid rain, and possible distal sources of smoke, suggestive of fire elsewhere in the UK/European basins. This terrestrial ecosystem perturbation is coincident with those in the marine realm, indicating ecosystem perturbations occurred across multiple habitats throughout the latest Rhaetian in the SW UK. Additionally, this geochemical approach reveals that the precursor carbon isotope excursion (CIE) routinely used in chemostratigraphic correlations is unrelated to LIP activity, but instead results from the increased input of terrestrially derived 13C-depleted plant material. Furthermore, we find the initial CIE (commonly used to mark the extinction level, but which is now known to precede the ETE) is also unrelated to biomass burning. Collectively, these data reveal that processes other than combustion of terrestrial material are important for the terrestrial phase of the ETE in the SW UK. Similar investigations are required on other ETE sections, both those in close proximity to the LIP driving the extinction and those further afield, to more clearly determine the negative effect(s) of LIPs and their geographic extent in the terrestrial realm.

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CFOX_EPSL_PAHs_Final (1) - Accepted Manuscript
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Accepted/In Press date: 6 February 2022
Venue - Dates: 30th International Meeting on Organic Geochemistry (IMOG 2021), Online, 2021-09-12 - 2021-09-17

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Local EPrints ID: 455094
URI: http://eprints.soton.ac.uk/id/eprint/455094
PURE UUID: f7f5655c-8508-4588-baaf-52f1a01890c8

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Date deposited: 08 Mar 2022 18:00
Last modified: 17 Mar 2024 07:11

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Contributors

Author: C.P. Fox
Author: P.E. Olsen
Author: K. Grice

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