Milankovitch-scale palynological turnover across the Triassic–Jurassic transition at St. Audrie's Bay, SW UK
Nina R. Bonis
Micha Ruhl
Wolfram M. Kürschner
10.6084/m9.figshare.3454832.v1
https://geolsoc.figshare.com/articles/journal_contribution/Milankovitch-scale_palynological_turnover_across_the_Triassic_Jurassic_transition_at_St_Audrie_s_Bay_SW_UK/3454832
<p>A high-resolution palynological study of the Triassic–Jurassic boundary in the St. Audrie's Bay section revealed a palynofloral
transition interval with four pronounced spore peaks in the Lilstock Formation. Regular cyclic increases in palynomorph concentrations
can be linked with periods of increased runoff, and correspond to the orbital eccentricity cycle. Spore peaks can be related
to precession-induced variations in monsoon strength. An implication is that the initial carbon isotope excursion lasted for
at least 20 ka. Emergence during deposition of the Cotham Member had an influence on one of the peaks, which is dominated
by spore-producing pioneer plants (e.g. horsetails and liverworts). There is no compelling evidence of a global end-Triassic
spore spike that, by analogy with the K–T boundary fern spike, could be related to a catastrophic mass extinction event. Climate
change is a more plausible mechanism to explain the increased amount of spores.
</p>
2016-06-21 12:22:53
SW UK
palynological study
20 ka
spore peaks
Lilstock Formation
climate change
palynomorph concentrations
Cotham Member
Bay section
eccentricity cycle
carbon isotope excursion
St
palynofloral transition interval
Triassic
monsoon strength
mass extinction event
Audrie
Spore peaks
Regular cyclic increases
Geology