Paper No. 9
Presentation Time: 10:35 AM
WHAT'S IN A NAME: EXTINCTIONS, EXCURSIONS, EVENTS AND EPIBOLES (OR WAS THIS HYPERBOLE?)
CRAMER, Bradley D.1, CONDON, Daniel
2, SÖDERLUND, Ulf
3, MARSHALL, Carly
4, WORTON, Graham
5, THOMAS, Alan
4, CALNER, Mikael
6, RAY, David C.
7, PERRIER, Vincent
8 and PATCHETT, P. Jonathan
9, (1)Kansas Geological Survey/Department of Geology, University of Kansas, 1930 Constant Avenue, Lawrence, KS 66047, (2)NERC Isotope Geoscience Laboratory, British Geological Survey, Keyworth, Nottingham, NG12 5GG, United Kingdom, (3)Department of Geology, Lund University, Sölvegatan 12, Lund, 22362, Sweden, (4)School of Geography, Earth, and Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, United Kingdom, (5)Dudley Museum and Art Gallery, Dudley, DY1 1HZ, United Kingdom, (6)GeoBioSphere Science Centre, Lund University, Sölvegatan 12, Lund, SE-223 62, Sweden, (7)Neftex Petroleum Consultants, Abingdon, OX14 4RY, United Kingdom, (8)Department of Geology, Institute of Ecology and Earth Sciences, University of Tartu, Tartu, 50411, Estonia, (9)Geosciences, University of Arizona, 1040 E 4th Street, Tucson, AZ 85721, cramerbd@gmail.com
Far from the stable, quiet and generally boring portrayal of the Silurian Period available only a few decades ago, the Silurian is now recognized as one of the biologically and geochemically most dynamic intervals of Earth history. A series of major biotic and chemical events took place during the Silurian Period, which is further bracketed by significant global change events at both its onset and close. Biological events such as mass extinctions and epiboles, and chemical events such as major positive excursions in δ
13C, occurred within close temporal proximity to one another during the Silurian, but the precise relationship (and in fact the existence of any relationship at all) between these biotic and chemical events is still a topic of considerable debate within the Silurian community.
Whereas the Earth systems science discussions of global change events within most periods of Earth history are now focusing on determining what the relationship is between the biological and chemical history of our planet, in the Silurian, we seem still to be hung up on the question of if there is a relationship between the biological and chemical history of our planet. It has been clearly demonstrated that these Silurian biotic events and chemical events do not occur at a single stratigraphic level but occur over a protracted interval, and similarly, that all clades are not impacted equally at each level or by each event. Rather than being a demonstration that they are therefore unrelated however, it is more likely that what we are seeing is a cascade of ecosystem collapse and recovery that carries unique paths for each clade, and has a separate but equally unique and inherently related chemical record for each event. From a community dynamics view, the major Wenlock δ13C excursions begin within the extinction interval, reach peak values during the survival interval, and persist through the recovery interval of these biotic events to which they are unavoidably, intimately related.
Ian Boomer and Lennart Jeppsson are also co-authors on this presentation, however, the abstract submission service limited the total number of authors to 10.
This is a contribution to the International Geoscience Programme (IGCP) Project 591 - The Early to Middle Paleozoic Revolution.
