My current research activities include projects in four main areas of study: (1) Sequence stratigraphy – reconstructing the history of relative sea level change during the Cretaceous; (2) Cyclostratigraphy – the application of cyclostratigraphic methods to develop astrochronologic time scales; (3) Integration of stable and radiogenic isotope proxies to study notable biogeochemical perturbations in Earth History (such as OAE’s, the PETM, etc.), with a recent focus on paleo-ocean acidification and the chemical evolution of Cretaceous oceans [in collaboration with department colleagues Matt Hurtgen and Andy Jacobson]; (4) Paleoecology and biostratigraphy of Cretaceous strata in the Western Interior basin.

My specific expertise includes stratigraphic, sedimentologic and geochemical analysis of sedimentary successions in outcrop and core to reconstruct the detailed temporal and environmental context of a sedimentary deposit (using biostratigraphy, cyclostratigraphic methods where possible, and integration of radioisotope dating via collaboration with colleagues).  Geochemical analyses mainly focus on fine-grained, and commonly organic carbon-enriched facies to derive (a) evidence of paleo-redox conditions, (b) records of changes in paleo-biogeochemical cycles, (c) interpretation of changes in paleo-oceanographic conditions and paleoclimate.  The specific geochemical tools I employ include measurements of elemental and isotopic proxies such as weight % TOC and CaCO3, other major, minor and trace elemental compositions useful for paleoenvironmental reconstruction, and stable isotopic compositions of bulk organic matter, carbonate phases, and other minerals (δ13C, δ18O).

I collaborate closely with departmental colleagues Matt Hurtgen and Andy Jacobson on the application of δ34S, δ44Ca, 87Sr/86Sr, and δ88/86Sr measurements to investigate changes in paleo-ocean chemistry spanning key events in Earth History.  I also maintain a series of external collaborations with researchers who share expertise in a wide range of complimentary approaches to paleoenvironmental reconstruction (such as Prof. Dave Selby from Durham University, whose expertise in Os isotope geochemistry has made for a very productive collaboration in recent years).

Research projects that I have pursued over my career span depositional environments from terrestrial to lacustrine to marine, and time periods from the Devonian to the modern. Study sites have mostly focused on the Western Interior and Appalachian Basins of North America, but increasingly include data from ODP sites, as well as selected sections in Europe, Asia, and South America.  These studies are detailed in my publications, and a list of my current and former students can be  found here.

Click on the images below to learn more about each of the four main research efforts.

Sequence Stratigraphy

Cyclostratigraphy & Astrochronology

Biogeochemical Perturbations

Cretaceous Paleoecology & Biostratigraphy



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