The rise and fall of Lake Bonneville between 45 and 10.5 ka The rise and fall of Lake Bonneville between 45 and 10.5 ka Part of the Geology Commons, Oceanography and Atmospheric Sciences and Meteorology Commons, Other Earth Sciences Commons, and the Other Environmental Sciences Commons Benson, L.V.; Lund, S.P.; Smoot, J.P.; Rhode, D.E.; Spencer, R.J.; Verosub, K.L.; Louderback, L.A.; Johnson, C.A.; Rye, R.O.; and Negrini, R.M., "The rise and fall of Lake Bonneville between 45 and 10.5 ka" (2011). USGS Staff --Published Research. 726. a b s t r a c tA sediment core taken from the western edge of the Bonneville Basin has provided high-resolution proxy records of relative lake-size change for the period 45.1e10.5 calendar ka (hereafter ka). Age control was provided by a paleomagnetic secular variation (PSV)-based age model for Blue Lake core BL04-4.Continuous records of d 18 O and total inorganic carbon (TIC) generally match an earlier lake-level envelope based on outcrops and geomorphic features, but with differences in the timing of some hydrologic events/states. The Stansbury Oscillation was found to consist of two oscillations centered on 25 and 24 ka. Lake Bonneville appears to have reached its geomorphic highstand and began spilling at 18.5 ka. The fall from the highstand to the Provo level occurred at 17.0 ka and the lake intermittently overflowed at the Provo level until 15.2 ka, at which time the lake fell again, bottoming out at w14.7 ka.The lake also fell briefly below the Provo level at w15.9 ka. Carbonate and d 18 O data indicate that between 14.7 and 13.1 ka the lake slowly rose to the Gilbert shoreline and remained at about that elevation until 11.6 ka, when it fell again. Chemical and sedimentological data indicate that a marsh formed in the Blue Lake area at 10.5 ka.Relatively dry periods in the BL04-4 records are associated with Heinrich events H1eH4, suggesting that either the warming that closely followed a Heinrich event increased the evaporation rate in the Bonneville Basin and (or) that the core of the polar jet stream (PJS) shifted north of the Bonneville Basin in response to massive losses of ice from the Laurentide Ice Sheet (LIS) during the Heinrich event. The second Stansbury Oscillation occurred during Heinrich event H2, and the Gilbert wet event occurred during the Younger Dryas cold interval. Several relatively wet events in BL04-4 occur during Dansgaard-Oeschger (DO) warm events.The growth of the Bear River glacier between 32 and 17 ka paralleled changes in the values of proxy indicators of Bonneville Basin wetness and terminal moraines on the western side of the Wasatch Mountains have ages ranging from 16.9 to 15.2 ka. This suggests a near synchroneity of change in the hydrologic and cryologic balances occurring in the Bonneville drainage system and that glacial extent was linked to lake size.

The Mono Lake excursion (MLE) is an important time marker that has been found in lake and marine sediments across much of the Northern Hemisphere. Dating of this event at its type locality, the Mono Basin of California, has yielded controversial results with the most recent effort concluding that the MLE may actually be the Laschamp excursion (Earth Planet. Sci. Lett. 197 (2002) 151). We show that a volcanic tephra (Ash x15) that occurs near the midpoint of the MLE has a date (not corrected for reservoir effect) of 28,6207300 14 C yr BP (B32,400 GISP2 yr BP) in the Pyramid Lake Basin of Nevada. Given the location of Ash x15 and the duration of the MLE in the Mono Basin, the event occurred between 31,500 and 33,300 GISP2 yr BP, an age range consistent with the position and age of the uppermost of two paleointensity minima in the NAPIS-75 stack that has been associated with the MLE (

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We correlate oscillations in the hydrologic and/or cryologic balances of four Great Basin surface-water systems with Dansgaard-Oeschger (D-O) events 2-12. This correlation is relatively strong at the location of the magnetic signature used to link the lake records, but becomes less well constrained with distance/time from the signature. Comparison of proxy glacial and hydrologic records from Owens and Pyramid lakes indicates that Sierran glacial advances occurred during times of relative dryness. If our hypothesized correlation between the lake-based records and the GISP2 d 18 O record is correct, it suggests that North Atlantic DO stades were associated with relatively cold and dry conditions and that interstades were associated with relatively warm and wet conditions throughout the Great Basin between 50,500 and 27,000 GISP2 yr B.P. The Great Basin lacustrine climate records reinforce the hypothesis that DO events affected the climate throughout much of the Northern Hemisphere during marine isotope stages 2 and 3. However, the absolute phasing between lake-size and ice-core d 18 O records remains difficult to determine.

High‐resolution paleomagnetic records from two sites near Pringle Falls, Oregon, are compared with similar records from Summer Lake, Oregon, ∼170 km to the southeast: Paoha Island, in Mono Lake, ∼660 km to the southeast and Benton Crossing, in Long Valley, approximately 700 km to the southeast, in east‐central California. The sequences at Pringle Falls contain a distinctive coarse pumice‐lapilli tephra layer which we have dated as 218±10 ka by 40Ar/39Ar step‐heating of plagioclase feldspar. Stratigraphically, this tephra is closely associated with a suite of several other tephra layers that bracket the interval studied paleomagnetically. Each tephra layer is distinguished by the unique chemical composition of its volcanic glass shards. The pumice layer dated at Pringle Falls is correlated with layers at three of the other localities. Using all the tephra layers, we can correlate the lake stratigraphic sequences and associated paleomagnetic records among the four distant localities. Additional age control is obtained from a fifth locality at Tulelake in northern California, where the stratigraphic interval of interest is bracketed between ∼171±43 and approximately 140 ka. Characteristics of the paleomagnetic records indicate virtually identical paleofield variation, particularly the geometry of a normal to normal (N‐N) geomagnetic polarity episode. The observed paleofield behavior resembles the Blake geomagnetic polarity episode, but is significantly older than the generally accepted age of the Blake episode. Either the age of the Blake episode is significantly underestimated, or the polarity episode documented here is older, perhaps the Jamaica episode, or is an as yet unreported episode. A corollary of the latter option is that paleomagnetic polarity episodes of different ages may have similar transition polar paths, a conclusion implying that a common mechanism is involved.