Andrew Cohen | Paleoclimates and Paleolimnology of Lakes and Lake Deposits in the US Great Basin

The University of Arizona’s Laboratory of Paleolimnology has had a long standing interest in the paleolimnology of the arid climate lakes and lake deposits of the western U.S., particularly in the Basin and Range Province. Studies by our group have included drill core investigations at Summer Lake Oregon, where we have integrated ostracode paleoecology and shell geochemistry with palynology, sedimentology and environmental magnetism studies (Palacios-Fest et al, 1993Cohen et al, 2000and Negrini et al, 2000). We have also studied the paleolimnology and paleoclimate history of the Great Salt Lake, including an analysis of Neogene cuttings records collected by AMOCO (Kowalewska and Cohen, 1998), and drill core records from the 2000 GLAD-800 drilling campaign, the first application of the Global Lakes Drilling System (Dean et al., 2002Balch et al, 2005). In the past decade our lab has been involved in a large, NSF-funded effort to better understand the controversial Mio-Pliocene Bouse Formation of the lower Colorado River Valley. The origin of the Bouse, particularly in its southern reaches between Parker and Yuma AZ has been intensely debate, as to whether it formed entirely in a lake, or in part within an estuary or arm of the Gulf of California. Our team’s paleoecological and geochemical results have contributed substantially to this debate (Bright et al., 2016; 2018a, 2018b. Over the past year we have also been heavily involved with plans to obtain drill cores from the Bouse depocenter to help resolve this debate (Cohen et al., 2019).


drill core shorelines

A. Stratigraphy of the 121m GSL-00-04 drill core from the Great Salt Lake, Utah. From Balch et al. (2005).

 

B. Late Quaternary Paleoshorelines around the south shore of the Great Salt Lake, Utah. Photo credit A. Cohen
upper bouse formation  

C. Pliocene Upper Bouse Formation near Parker AZ (Mesquite Mtn. area). Photo credit A. Cohen.

 

 
lower bouse carbonate

D. Spectacular “travertufas” of the lower Bouse Formation, near Moon Mountain, south of Parker AZ. Photo credit A. Cohen.

E. Controversial carbonate grainstones of the lower Bouse Formation in Blythe Basin, near Cibola, AZ. Photo credit A. Cohen