[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

RE: Wildfires in Cretaceous world



From: Ben Creisler
bcreisler@gmail.com


The paper is now out online:



Sarah A.E. Brown, Andrew C. Scott, Ian J. Glasspool & Margaret E.
Collinson (2012)
Cretaceous wildfires and their impact on the Earth system.
Cretaceous Research (advance online publication)
http://dx.doi.org/10.1016/j.cretres.2012.02.008
http://www.sciencedirect.com/science/article/pii/S019566711200016X


A comprehensive compilation of literature on global Cretaceous
charcoal occurrences shows that from the Valanginian on throughout the
Cretaceous, terrestrial sedimentary systems frequently preserve
charcoal in abundance. This observation indicates that fires were
widespread and frequent and that the Cretaceous can be considered a
“high-fire” world. This increased fire activity has been linked to
elevated atmospheric oxygen concentrations, predicted as in excess of
21% throughout this period and 25% during some stages. This extensive
wildfire activity would have affected the health, composition, and
structure of the vegetation and, through habitat loss, probably the
fauna. For these reasons, fire activity should be taken into account
in Cretaceous vegetation and climate models. Major changes in
vegetation occurred during the Cretaceous. In particular, the
angiosperms rose to dominance. Some early angiosperms are interpreted
as being of weedy form and as having thrived in disturbed
environments. Fires may have promoted angiosperm diversification and
spread through their role in environmental perturbation. The
significant number of charred angiosperm mesofossil assemblages
described from the late Early Cretaceous supports this hypothesis.
Additionally, it can be speculated that severe fires during the
Cretaceous would have engendered increased levels of runoff and
erosion leading to the mobilization of significant amounts of
phosphorous into marine settings. This phosphorous runoff would have
contributed to oceanic planktonic blooms and their associated anoxic
events. Fire activity remained prevalent into the Late Cretaceous. New
data on the distribution of charcoal in the Campanian of Dinosaur
Provincial Park, Canada indicate extensive charcoal deposits over a
1.7 myr interval and suggest that some catastrophic bone bed
accumulations may have been the result of post-fire
erosion-depositional systems.