| Summary: | Records of sediment magnetism of the B&B core from the depocenter of Summer Lake basin, south-central Oregon, are compared with global and local proxies of climate from 46 to 23 ka. B&B core magnetic-concentration records appear to correlate well with the Greenland Ice Sheet Project 2 (GISP2) 0180 record, an indicator of climate conditions in the North Atlantic region. In particular, three low-frequency Bond cycles, the associated Heinrich events, and high-frequency Dansgaard-Oeschger cycles are all observed in the B&B core magnetic-concentration record. High magnetite concentration values are correlated with interstadial events, and low values are correlated with stadial events. Previous studies of Summer Lake sediments indicate that concentration of magnetite is correlated with lake-levels (e.g., Negrini et al., 2000). New chronology resulting from curve matching mostly agrees with independently determined age control of Negrini et al. (2000), and with new 14C dates. The above results are consistent with previous studies that show increase in late Pleistocene precipitation and lake-levels in the Great Basin during the interstadial halves of D-O cycles (Hakala et al., 1997; Benson, 1999). In addition, sparsely sampled palynological, geochemical, and lithologic data from the B&B core generally support the model wherein increased rainfall in the study area during periods of warm global climate led to higher lake-levels.
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