Masters Thesis: Sedimentary and climatic response to the Second Eocene Thermal Maximum in the McCullough Peaks Area, Bighorn Basin, Wyoming, U.S.A. (Done with open publishing: free to read)
I completed my thesis research under the greater umbrella of the Bighorn Basin Coring Project. BBCP is interested in hyperthermals – geologically short-term (~200kyr) climactic warming events caused by the rapid input of isotopically light carbon from terrestrial reservoirs. (Though the exact reservoir is still up for debate, destabilization of methane clathrates seem the most likely as of right now – see McInerney and Wing (2011) for a more thorough discussion.) In addition to warming the climate, the input of carbon into the atmosphere also had other effects – it caused the carbonate lysocline to shoal in the oceans, which made life very difficult for carbonate-precipitating organisms and caused extinctions among benthic forams (e.g.: Alegret et al., 2009), and also seems to have made all of the mammals become tiny and cute, though we’re not quite sure why that is as of yet. (e.g.: Secord et al., 2012), among other effects still being studied. The Paleocene-Eocene Thermal Maximum is the most well-studied of these events and was also the greatest in magnitude. The hyperthermal of interest to me is ETM2, which was about half the magnitude of the PETM. I’m using cores drilled at Gilmore Hill in the Bighorn Basin, Wyoming, USA, to study climate patterns through the time period leading up to ETM2. The cores come from the Willwood Formation, which is primarily made of meandering river sandstones and overbank deposits, which later developed into soils. The soils “fossilized” into paleosols, which I am in the process of describing and analyzing.
So why do we care about hyperthermals? Well, in the big picture sense, it’s part of the greater history of our planet, and understanding climate controls and forcings is generally valuable; geology is all about connecting the present Earth with the Earth of the past. But perhaps what makes research into the PETM and similar events particularly relevant is that they represent a natural occurrence of global warming caused by atmospheric input of isotopically light carbon. And atmospheric input of light carbon is what humanity is currently doing at a breathtaking rate, one which exceeds the “rapid” input seen during the PETM. Studying the effect of that sort of climate shift on one continental site is one more small piece of the puzzle.
The Paleocene-Eocene Thermal Maximum: a Perturbation of Carbon Cycle, Climate, and Biosphere with Implications for the Future (McInerney and Wing, 2011) – This is an excellent overview paper of current PETM research if you want to know more!
Terrestrial carbon isotope excursions and biotic change during Palaeogene hyperthermals (Abels et al., 2012) – A paper regarding the appearance of the ETM2 and H2 hyperthermals at two sites in the Bighorn Basin, Wyoming, USA. The Gilmore Hill section is about 1km from the Gilmore Hill site my cores come from, and I’m working on ETM2 and the climate leading up to it.