Unraveling Cenozoic climate and tectonics in western North America using lake sediments

March 17^th (Tuesday), 6 p.m., Teton Co. Library Auditorium – Open to Public. Presentation: “Unraveling Cenozoic climate and tectonics in western North America using lake sediments”, Presented by Daniel Enrique Ibarra, UC Berkeley.

Terrestrial basins host important archives used to reconstruct both surface elevation and past hydroclimate in western North America. Importantly, lacustrine deposits in these basins suggest wetter conditions during both colder- and warmer-than-present periods in the past, and the north to south growth of the Rocky Mountains since the retreat of the Cretaceous seaway. To quantify hydrologic changes and past surface elevations I model the size distribution of lakes, make geochemical analyses of terrestrial sediments and compile maps of isotope measurements from key time periods. Examples will include: 1) measurements showing Cenozoic drying of the John Day Fossil Beds National Monument region; 2) stable isotope analyses of kaolinite samples from the gold-bearing Eocene river gravels in the northern Sierra Nevada; and 3) new triple oxygen and clumped isotope measurements on lacustrine chert and carbonates from the Eocene Green River Formation in the Flagstaff Basin, Utah. In carrying out these analyses I demonstrate that the tectonic evolution and long-term cooling over the Cenozoic shape the landscape we observe today in the North American Cordillera.

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