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Keywords:

  • PETM;
  • continental scientific drilling;
  • Bighorn Basin

Scientists have begun a new project to recover and study sediment cores in the Bighorn Basin of Wyoming to investigate the high-frequency climatic and biotic variability of a continental depositional system during past episodes of greenhouse conditions. The project, called the Bighorn Basin Coring Project (BBCP), focuses on the early Paleogene (∼50–65 million years ago), the most recent interval of Earth history characterized by greenhouse climate conditions. During the early Paleogene, global mean annual temperatures were up to 10°C higher than today, and carbon dioxide (CO2) concentrations may have been more than 1000 parts per million [Zachos et al., 2008] compared with the roughly 390 parts per million today. Superimposed on this background greenhouse climate state were a series of short-term extreme warming events called hyperthermals. The best known early Paleogene hyperthermal event is the Paleocene-Eocene Thermal Maximum (PETM; ∼56 million years ago), which is characterized by a large global carbon isotope excursion and coincides with major changes to marine and continental ecosystems [McInerney and Wing, 2011]. At present, the causes of these hyperthermal events remain unknown, although several hypotheses exist.