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Synchronous wildfire activity rise and mire deforestation at the triassic-jurassic boundary.
PLoS One. 2012; 7(10):e47236.Plos

Abstract

The end-Triassic mass extinction event (∼201.4 million years ago) caused major faunal and floral turnovers in both the marine and terrestrial realms. The biotic changes have been attributed to extreme greenhouse warming across the Triassic-Jurassic (T-J) boundary caused by massive release of carbon dioxide and/or methane related to extensive volcanism in the Central Atlantic Magmatic Province (CAMP), resulting in a more humid climate with increased storminess and lightning activity. Lightning strikes are considered the primary source of wildfires, producing charcoal, microscopically recognized as inertinite macerals. The presence of polycyclic aromatic hydrocarbons (PAHs) of pyrolytic origin and allochthonous charcoal in siliciclastic T-J boundary strata has suggested widespread wildfire activity at the time. We have investigated largely autochthonous coal and coaly beds across the T-J boundary in Sweden and Denmark. These beds consist of predominantly organic material from the in situ vegetation in the mires, and as the coaly beds represent a substantial period of time they are excellent environmental archives. We document a remarkable increase in inertinite content in the coal and coaly beds across the T-J boundary. We show estimated burning temperatures derived from inertinite reflectance measurements coupled with palynological data and conclude that pre-boundary late Rhaetian mire wildfires included high-temperature crown fires, whereas latest Rhaetian-Sinemurian mire wildfires were more frequent but dominated by lower temperature surface fires. Our results suggest a major change in the mire ecosystems across the T-J boundary from forested, conifer dominated mires to mires with a predominantly herbaceous and shrubby vegetation. Contrary to the overall regional vegetation for which onset of recovery commenced in the early Hettangian, the sensitive mire ecosystem remained affected during the Hettangian and did not start to recover until around the Hettangian-Sinemurian boundary. Decreasing inertinite content through the Lower Jurassic suggests that fire activity gradually resumed to considerable lower levels.

Authors+Show Affiliations

Department of Reservoir Geology, Geological Survey of Denmark and Greenland-GEUS, Copenhagen, Denmark. hip@geus.dkNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

23077574

Citation

Petersen, Henrik I., and Sofie Lindström. "Synchronous Wildfire Activity Rise and Mire Deforestation at the Triassic-jurassic Boundary." PloS One, vol. 7, no. 10, 2012, pp. e47236.
Petersen HI, Lindström S. Synchronous wildfire activity rise and mire deforestation at the triassic-jurassic boundary. PLoS ONE. 2012;7(10):e47236.
Petersen, H. I., & Lindström, S. (2012). Synchronous wildfire activity rise and mire deforestation at the triassic-jurassic boundary. PloS One, 7(10), e47236. https://doi.org/10.1371/journal.pone.0047236
Petersen HI, Lindström S. Synchronous Wildfire Activity Rise and Mire Deforestation at the Triassic-jurassic Boundary. PLoS ONE. 2012;7(10):e47236. PubMed PMID: 23077574.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Synchronous wildfire activity rise and mire deforestation at the triassic-jurassic boundary. AU - Petersen,Henrik I, AU - Lindström,Sofie, Y1 - 2012/10/15/ PY - 2012/07/06/received PY - 2012/09/10/accepted PY - 2012/10/19/entrez PY - 2012/10/19/pubmed PY - 2013/7/20/medline SP - e47236 EP - e47236 JF - PloS one JO - PLoS ONE VL - 7 IS - 10 N2 - The end-Triassic mass extinction event (∼201.4 million years ago) caused major faunal and floral turnovers in both the marine and terrestrial realms. The biotic changes have been attributed to extreme greenhouse warming across the Triassic-Jurassic (T-J) boundary caused by massive release of carbon dioxide and/or methane related to extensive volcanism in the Central Atlantic Magmatic Province (CAMP), resulting in a more humid climate with increased storminess and lightning activity. Lightning strikes are considered the primary source of wildfires, producing charcoal, microscopically recognized as inertinite macerals. The presence of polycyclic aromatic hydrocarbons (PAHs) of pyrolytic origin and allochthonous charcoal in siliciclastic T-J boundary strata has suggested widespread wildfire activity at the time. We have investigated largely autochthonous coal and coaly beds across the T-J boundary in Sweden and Denmark. These beds consist of predominantly organic material from the in situ vegetation in the mires, and as the coaly beds represent a substantial period of time they are excellent environmental archives. We document a remarkable increase in inertinite content in the coal and coaly beds across the T-J boundary. We show estimated burning temperatures derived from inertinite reflectance measurements coupled with palynological data and conclude that pre-boundary late Rhaetian mire wildfires included high-temperature crown fires, whereas latest Rhaetian-Sinemurian mire wildfires were more frequent but dominated by lower temperature surface fires. Our results suggest a major change in the mire ecosystems across the T-J boundary from forested, conifer dominated mires to mires with a predominantly herbaceous and shrubby vegetation. Contrary to the overall regional vegetation for which onset of recovery commenced in the early Hettangian, the sensitive mire ecosystem remained affected during the Hettangian and did not start to recover until around the Hettangian-Sinemurian boundary. Decreasing inertinite content through the Lower Jurassic suggests that fire activity gradually resumed to considerable lower levels. SN - 1932-6203 UR - https://www.unboundmedicine.com/medline/citation/23077574/Synchronous_wildfire_activity_rise_and_mire_deforestation_at_the_triassic_jurassic_boundary_ L2 - http://dx.plos.org/10.1371/journal.pone.0047236 DB - PRIME DP - Unbound Medicine ER -