The Technical Version
Late Cretaceous strata in the Cordilleran Foreland Basin, North America, is world-renowned for preserving a rich fossil and paleoenvironmental history representing the peak of dinosaur species diversity. Abundant volcanic ash horizons interstratified with fossil-bearing units throughout the basin make it a perfect setting to apply high-precision U-Pb zircon dating by chemical abrasion ID-TIMS to the stratigraphic record. The key fossil-bearing units that are examined in my project comprise a variety of distinct Campanian terrestrial sedimentary units deposited along the basin’s western margin from Alberta to Utah.
My work also aims to broaden the reach and effectiveness of high-precision geochronology through refined stratigraphic correlations using a multifaceted geochemical approach to characterising bentonite marker horizons. Geochemical characterisation of volcanic material, a process called tephrostratigraphy, is often hampered in pre-Quaternary deposits due to chemical alteration during ash devitrification. This project investigates major element characterisation of the Campanian bentonites through the novel use of glass (melt) inclusions that are encased within the same volcanic zircon crystals used for geochronology, and thus are protected from alteration. Multiple geochemical systems are employed to support fingerprinting of bentonites including trace element composition and Lu-Hf isotopic systematics. This multifaceted approach will facilitate the construction of a high-resolution chronostratigraphic framework for the basin by relatively inexpensive and accessible means and is entirely transferable to other basins and time periods.
The Fun Version
People like dinosaurs. Like, REALLY like them. Have you seen any of the latest Jurrasic Park / World movies lately? (They are only getting more and more wild!!). A true dino fan would spot the blaring inaccuracies in these movies with delight; “Did you know WE lived closer in time to T-rex than most pterodactyls did!”. This tells us two things: humans are really creative (to make such exciting books and movies as mentioned) AND people are genuinely interested! We want to know! Indeed, this research may not be solving world-threatening challenges, but it’s a good news day whenever we hear about our favourite reptilian overlords.
HOWEVER, the first challenge; when DID the dinosaurs live? Yea okay, a long time ago… but if I wrote “twenty-something years old” on my driver’s licence, I don’t think the Department of Transport would be very happy with me. To figure out who lived with who and where the family trees come from, we need to know how old any given dino is with enough confidence that we can say it does or doesn’t overlap with their neighbours.
This is the central pillar of my work; using highly precise methods call CA ID TIMS we can refine the ages of dinosaurs from the richest part of the Mesozoic era to within tens of thousands of years. Studying the rocks from which these numbers were derived also allows us to look into what else was happening when dinosaurs roamed the earth. For example, can you picture in your head a scene of a dinosaur roaring up at an exploding volcano? Popular culture would have you believe volcanos and dinosaurs go hand in hand… and maybe there is some truth to it! Stay tuned for more details!