Holocene climate in the Northern Great Plains inferred from sediment stratigraphy, stable isotopes, carbonate geochemistry, diatoms, and pollen at Moon Lake, North Dakota

Seismic stratigraphy, sedimentary facies, pollen stratigraphy, diatom-inferred salinity, stable isotope (delta(18)O and delta(13)C), and chemical composition (Sr/Ca and Mg/Ca) of authigenic carbonates from Moon Lake cores provide a congruent Holocene record of effective moisture for the eastern Northern Great Plains, Between 11,700 and 9500 C-14 yr B.P., the climate was cool and moist, A gradual decrease in effective moisture occurred between 9500 and 7100 C-14 yr B.P. A change at about 7100 C-14 yr B.P. inaugurated the most arid period during the Holocene. Between 7100 and 4000 C-14 yr B.P., three arid phases occurred at 6600-6200 C-14 yr B.P., 5400-5200 C-14 yr B.P., and 4800-4600 C-14 yr B.P. Effective moisture generally increased after 4000 C-14 yr B.P., but periods of low effective moisture occurred between 2900-2800 C-14 yr B.P. and 1200-800 C-14 yr B.P. The data also suggest high climatic variability during the last few centuries, Despite the overall congruence, the biological (diatom), sedimentological, isotopic, and chemical proxies were occassionally out of phase, At these times the evaporative process was not the only control of lake-water chemical and isotopic composition. (C) 1997 University of Washington.