Mass balance calculations indicate that a massive amount of 13C-depleted carbon was released into the early Danian atmosphere in volumes comparable with the younger Paleocene-Eocene thermal maximum (PETM). This Danian hyperthermal event (the Dan-C2) has been documented from the fill of the Boltysh meteorite crater, Ukraine. Palynofloras recovered from the Boltysh crater fill show a trend from mesic forest to savannah ecosystem dominance on a millennial scale across the hyperthermal inception with no abrupt compositional shift. This longer term trend is overprinted by moisture availability oscillations reflecting orbital forcing. Forcing is not directly tracked by the oscillations, which are composed of mesic forest and savannah palynofloras separated by rapid critical transitions. The absence of an ecological collapse at the Dan-C2 indicates that plant ecosystems experienced dominant forcing from orbital cyclicity, rather than a stochastic temperature rise.
Bibliographical noteAcknowledgements and Funding
The authors are extremely grateful for the receipt of NERC award NE/ D005043/1, which funded the initial Boltysh impact crater study. R. Spicer and J. Leake are thanked for interesting discussions. C. Wellman, W. Gosling and M. Donovan are thanked for constructively critical reviews of the paper. Scientific editing by Quentin Crowley