The Lamont Earth Science Colloquium presents:
A Giant Arctic Continent at the Dawn of the Age of Dinosaurs
with Dr. Paul Olsen, Arthur D. Storke Memorial Professor, Biology and Paleo Environment, Lamont-Doherty Earth Observatory.
A huge, newly recognized landmass composed of Siberian and East Asian blocks stretched across the Arctic during the Early Mesozoic (252–175 Ma), shaping global climate and sea level during the Triassic–Jurassic transition. Lake ice rafted debris in northwestern China shows that widespread seasonal freezing prevailed along the southern margin of this high latitude landmass, which was also home to dinosaurs. Such a large polar continent would be expected to enhance continentality, promoting colder winters, mountain glaciation, and perhaps a modest ice cap, consistent with background glacioeustatic sea level fluctuations. An abrupt sea level fall stands out above this background; it was coincident with the end Triassic mass extinction at 201.6 Ma and the onset of Central Atlantic Magmatic Province volcanism, which plausibly produced “volcanic winters” that in turn triggered rapid ice sheet growth, forcing the abrupt drop in sea level. The resulting expansion of high latitude ice may have increased Earth System sensitivity to polar orbitally paced climate, producing a newly observed and unexpected ~400 kyr shift in tropical climate from precession to obliquity and back, and a transient hothouse to icehouse shift. These same volcanic winters may have selectively eliminated large, non insulated terrestrial vertebrates, allowing already cold adapted, insulated dinosaurs in the Arctic to become ecological dominants globally.
The Earth Science Colloquium Series, sponsored by Lamont-Doherty Earth Observatory and Columbia University Department of Earth and Environmental Sciences (DEES), provides a lively forum for discussing a wide variety of topics within the Earth sciences and related fields. Colloquia are attended by the full range of scientific and technical staff at LDEO. Colloquium attendance is required of all pre-orals DEES graduate students.
