The early Paleogene is the most recent interval of earth history that is characterized by greenhouse climate conditions where global mean annual temperatures were up to 10°C higher than today. CO2 concentrations may have been ›1000 ppm. Superimposed on this greenhouse climate state are a series of short-term extreme warming events ("hyperthermals") that are hypothesized to be orbitally paced and may have triggered significant biotic changes. The best known of these hyperthermal events is the PETM (Paleocene-Eocene Thermal Maximum) which is characterized by a global carbon isotope excursion. It coincides with major changes to marine and continental ecosystems.
The Bighorn Basin preserves the most complete early Paleogene continental sequence in the world, which includes a ~50 meter thick PETM interval. Cores of this early Paleogene stratigraphic record will make it possible to develop high resolution (1,000-10,000 year sampling interval) proxy records for temperature (oxygen isotopes), carbon cycling (carbon isotopes), and biotic change (e.g. pollen) from unweathered material. This will allow us to investigate, in an unprecedented way, the high-frequency climatic and biotic variability of a continental depositional system during greenhouse conditions.
The new record will be used to address questions that are difficult or impossible to answer using discontinuous and highly weathered surface sections. For instance, are other hyperthermal events besides the PETM preserved in the Bighorn Basin stratigraphic record? If so, do they correlate with observed biotic events and is their temporal distribution consistent with orbital pacing? What is the detailed shape of the carbon isotope excursion across the PETM and does it reveal clues about the cause of this (and other) hyperthermals? What was the continental sedimentary response to the PETM (and other hyperthermals)? Do the fluvial-lacustrine sediments in the Bighorn Basin show orbital scale cyclicity?
Phase I: Planning
- Planning Workshops of the BBCP was a NSF supported workshop that took place in Powell, Wyoming from June 24 - June 27, 2007. The workshop determined the scientific, administrative, and logistic framework of the BBCP.
- We finalized the formal drilling prospectus during 2008.
- Full drilling proposal to NSF was submitted in August of 2009 and the BBCP proposal was funded in October of 2010.
- Final Planning Meeting was held March 25-27, 2011 at the Denver Museum of Nature and Science, our outreach partner.
Phase II: Drilling
- Drilling completed in August of 2011.
- Cores were split, described, scanned, sampled, and archived during a three-week trip to the Bremen Core Repository in January of 2012. Initial scientific results started to be presented during 2012-2013.
Drilling crew working on rig during coring at Polecat Bench (photo by E. Denis).