SMAST Seminar - DEOS - October 23, 2024 - "Uncovering the history of the Bering Land Bridge using the Arctic Ocean's nitrogen cycle" By: Jesse Farmer
When: Wednesday,
October 23, 2024
12:30 PM
-
1:30 PM
Where: > See description for location
Description: Department of Estuarine and Ocean Sciences
"Uncovering the history of the Bering Land Bridge using the Arctic Ocean's nitrogen cycle"
Jesse Farmer, Assistant Professor in the School for the Environment at the University of Massachusetts Boston
Wednesday, October 23, 2024
12:30-1:30pm
SMAST E 101-102 and via Zoom
Abstract:
Beringia, the region between the Lena River in northeastern Russia and the Mackenzie River in northwestern North America, has experienced profound changes in relative sea level that fundamentally reshaped Northern Hemisphere terrestrial and ocean connections. Today, Beringia centers on the Bering Strait, a ~50 m deep gateway that links the Pacific and Atlantic Oceans via the Arctic Ocean. This modern arrangement has been ephemeral over recent Earth history, with a ~1000 km-wide land bridge at the Last Glacial Maximum (LGM, ~20,000 years ago) providing the long-proposed route by which humans first migrated to North America. However, direct information on past Beringian sea level has only existed for times after the LGM. This greatly limits our knowledge of the timing of and environmental context for past migrations, including that of our human ancestors.
Here I will present new reconstructions of past Bering Strait flooding using foraminifera-bound nitrogen isotopes to trace the “fingerprint” of Pacific nitrogen input into the Arctic Ocean. Results show that the Bering Strait was flooded immediately prior to the LGM and date the formation of the Bering Land Bridge to ~36,000 years ago. These results require much higher global mean sea level prior to the LGM than previously thought, and limit the duration over which the land bridge was available for terrestrial migrations. Corroborating evidence for a late land bridge formation from terrestrial paleogenomics will be presented. Finally, I will discuss preliminary results from an extension of the nitrogen isotope approach back to ~130,000 years ago.
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For additional information, please contact Callie Rumbut at c.rumbut@umassd.edu
"Uncovering the history of the Bering Land Bridge using the Arctic Ocean's nitrogen cycle"
Jesse Farmer, Assistant Professor in the School for the Environment at the University of Massachusetts Boston
Wednesday, October 23, 2024
12:30-1:30pm
SMAST E 101-102 and via Zoom
Abstract:
Beringia, the region between the Lena River in northeastern Russia and the Mackenzie River in northwestern North America, has experienced profound changes in relative sea level that fundamentally reshaped Northern Hemisphere terrestrial and ocean connections. Today, Beringia centers on the Bering Strait, a ~50 m deep gateway that links the Pacific and Atlantic Oceans via the Arctic Ocean. This modern arrangement has been ephemeral over recent Earth history, with a ~1000 km-wide land bridge at the Last Glacial Maximum (LGM, ~20,000 years ago) providing the long-proposed route by which humans first migrated to North America. However, direct information on past Beringian sea level has only existed for times after the LGM. This greatly limits our knowledge of the timing of and environmental context for past migrations, including that of our human ancestors.
Here I will present new reconstructions of past Bering Strait flooding using foraminifera-bound nitrogen isotopes to trace the “fingerprint” of Pacific nitrogen input into the Arctic Ocean. Results show that the Bering Strait was flooded immediately prior to the LGM and date the formation of the Bering Land Bridge to ~36,000 years ago. These results require much higher global mean sea level prior to the LGM than previously thought, and limit the duration over which the land bridge was available for terrestrial migrations. Corroborating evidence for a late land bridge formation from terrestrial paleogenomics will be presented. Finally, I will discuss preliminary results from an extension of the nitrogen isotope approach back to ~130,000 years ago.
----------------------------------------------------
For additional information, please contact Callie Rumbut at c.rumbut@umassd.edu
Contact: > See Description for contact information
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