Frasnian-Famennian (Late Devonian) mass extinction project

My PhD research, from 2001-2004, investigated changes in the oceans during the Frasnian-Famennian extinction interval. This extinction is now well known as one of the "Big 5" Phanerozoic extinctions (of Raup and Sepkoski, 1982), but there remain several conflicting hypotheses as to the cause. My research tested whether widespread marine anoxia, a leading candidate for the causal mechanism, was responsible. This was tested by geochemical and microfacial proxies for redox conditions in the oceans, from widespread locations (present day Poland, Germany, France, New York State, Nevada, and Utah). Techniques applied included gamma-ray spectrometry, pyrite framboid analysis, and petrographic analysis. For more details on these techniques, visit my publications using the link on the left. Of course, it is impossible to test extinction scenarios without properly constraining the timing of extinctions. Until recently, most faunal data was at an insufficient resolution to allow for this. Whilst investigating the changes in ocean chemistry, therefore, it was also necessary for me to build up a high resolution faunal database. Ultimately, I was able to demonstrate that marine anoxia developed synchronusly, in geographically widespread locations, simultaneous with the peak of extinctions, very close to the end of the Frasnian. This suggests that anoxia at least played a major role in the extinction scenario. As to the ultimate cause of the anoxia? Well that is an ongoing question...

BUT as of 2009 I am revisiting this topic with fieldwork on Devonian reefs in Canada and Australia (haven't managed to get out there yet, and its summer 2011). So I might know the answers soon.

To access the Discussion chapter from my thesis click here. (pdf document)

Here are some photos from my PhD days (click an image to enlarge).