Geological Society of America

T134 Grand Canyon, Colorado Plateau, and Rocky Mountain Debates and Their Global Reverberations, 150 Years after Powell I

Monday, 23 September 2019
1:30 PM - 5:30 PM
Room 221AB, North Building

EXPLORING HYDROCLIMATIC CONNECTIONS BETWEEN THE BLYTHE BASIN, ARIZONA AND WESTERN PLIOCENE LAKES OF NORTH AMERICA

Paper number: T134-15
Program: Technical Sessions
Time: 4:50 PM – 5:05 PM

Authors

Alison Smith Presenting Author
Kent State University, Kent, OH
Blas Lorenzo Valero-Garces
Spanish National Research Council, Zaragoza
Josef Werne
University of Pittsburgh, Pittsburgh, PA
John Williams
University of Wisconsin-Madison, Madison, WI
Emi Ito
University of Minnesota, Minneapolis, MN
Sherilyn C. Fritz
University of Nebraska-Lincoln, Lincoln, NE
Rob Hatfield
Oregon State University, Corvallis, OR
Tony Layzell
Lawrence, KS
Tim Lowenstein
Binghamton University, Binghamton, NY
David McGee
MITEarth, Atmos. and Planetary Sciences, Cambridge, MA
Peter Molnar
University of Colorado, Boulder, CO
Ivanka Stefanova
University of Minnesota, Minneapolis, MN

Abstract

Geologic studies of the Pliocene North American West show the evidence of large permanent freshwater lakes and other sedimentological and ecological features of persistent wet conditions, which prevailed until the Quaternary. Basins of Pliocene age with hundreds of meters of paleolacustrine and paleofluvial-lacustrine sediments include among others: Lake Idaho, Idaho; Butte Valley Lake, Tule Lake, Searles Lake, California; Blythe Basin and Verde Valley, Arizona. Paleolimnological studies based on analyses of pollen, ostracodes, diatoms, sediments, vertebrates and stable isotopes have shown the temporal linkage of these sites, but a clear understanding of how these wet conditions could be sustained for 10⁵ to 10⁶ years is lacking. Two proposed mechanisms for a wetter North American West during the Pliocene include permanent El Niño-like conditions, or a lower meridional temperature gradient, leading to expanded Hadley Cell expanding the tropical rain bands, bringing summer rain to the southern Great Basin, and pushing the zone of winter precipitation farther north.

We describe the opportunities presented by these sites for exploring the hydroclimatic conditions of the Pliocene North American West. By considering possible global and hemispheric precipitation processes, we may be able to understand future hydroclimatic changes in the North American West, in a warming world that already shows similarities with the Pliocene Epoch. We hope to generate interest in linking ongoing studies of the western lake basins with those of the Blythe Basin, including the Bouse Formation,and the Pliocene history of the Colorado River, the focus of this session. The considerable and sustained amount of water moving through the Blythe Basin during the early development of the Colorado River in the Pliocene Epoch may be linked to the hydroclimatic processes that supplied and maintained the large lake basins further west during this time. In order to capture a broad understanding of how the North American West responded to wetter and warmer conditions of the Pliocene, future drilling sites should include the Blythe Basin.

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-335514

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