Flame out! End-Triassic mass extinction polycyclic aromatic hydrocarbons reflect more than just fire
Flame out! 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 δ 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 elsewhere 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.
PAHs, St. Audrie's Bay, biomarkers, end-Triassic mass extinction, organic geochemistry
Fox, C.P.
11adb22e-5474-4e6a-966a-c5da6090b352
Whiteside, J.H.
5d9ad7aa-eba3-4ad9-9f6f-81be71b6829b
Olsen, P.E.
bdbec40b-82ed-41ac-8028-b6c333206f16
Grice, K.
5727db9b-587e-4b50-94df-d4521f938c71
15 April 2022
Fox, C.P.
11adb22e-5474-4e6a-966a-c5da6090b352
Whiteside, J.H.
5d9ad7aa-eba3-4ad9-9f6f-81be71b6829b
Olsen, P.E.
bdbec40b-82ed-41ac-8028-b6c333206f16
Grice, K.
5727db9b-587e-4b50-94df-d4521f938c71
Fox, C.P., Whiteside, J.H., Olsen, P.E. and Grice, K.
(2022)
Flame out! End-Triassic mass extinction polycyclic aromatic hydrocarbons reflect more than just fire.
Earth and Planetary Science Letters, 584, [117418].
(doi:10.1016/j.epsl.2022.117418).
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 δ 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 elsewhere 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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Flame out! End-Triassic mass extinction polycyclic aromatic hydrocarbons reflect more than just fire
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Accepted/In Press date: 6 February 2022
Published date: 15 April 2022
Additional Information:
Funding Information:
We acknowledge Peter Hopper, Alex Holman, and P. Sargent Bray for technical support and Leszek Marynowski for providing additional PAH data from their 2009 publication. Funding: Fox acknowledges Curtin University , the European Association of Organic Geochemistry , and Khalifa University of Science and Technology ( CIRA-2019-066 ). Fox and Grice thank the ARC ( LP150100341 ; LE110100119 ; LE100100041 ; LE0882836 ). Whiteside thanks the NSF ( EAR 1147402 ). Olsen acknowledges the Lamont Climate Center.
Publisher Copyright:
© 2022 Elsevier B.V.
Copyright:
Copyright 2022 Elsevier B.V., All rights reserved.
Keywords:
PAHs, St. Audrie's Bay, biomarkers, end-Triassic mass extinction, organic geochemistry
Identifiers
Local EPrints ID: 457049
URI: http://eprints.soton.ac.uk/id/eprint/457049
ISSN: 0012-821X
PURE UUID: 47c2a8a9-9193-4246-8a0c-cf85c1d8a559
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Date deposited: 20 May 2022 16:47
Last modified: 17 Mar 2024 07:17
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Author:
C.P. Fox
Author:
P.E. Olsen
Author:
K. Grice
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