11,000 year diatom-derived salinity record, interpreted as a drought intensity
and frequency proxy on the Great Plains of North America Site: Moon Lake, North
Dakota, USA (46 51' 27" N, 98 09' 30" W. ~35 ha, max. depth ~13m).
ABSTRACT (from the online documentation):
Estimates of past lake-water salinity from fossil diatom assemblages
were used to infer past climatic conditions at Moon Lake, a ... climatically
sensitive site in the northern Great Plains. A good correspondence between
diatom-inferred salinity and historical records of mean annual precipitation
minus evapotranspiration (P-ET) strongly suggests that the sedimentary record
from Moon Lake can be used to reconstruct past climatic conditions.
Century-scale analysis of the Holocene diatom record indicates four major
hydrological periods: an early Holocene transition from an open freshwater
system to a closed saline system by 7300 BP, which corresponds with a
transition from spruce forest to deciduous parkland to prairie and indicates a
major shift from wet to dry climate; a mid-Holocene period of high salinity
from 7300 to 4700 BP, indicating low effective moisture (P-ET); a transitional
period of high salinity 4700 to 2200 BP, characterized by poor diatom
preservation; and a late Holocene period of variable lower salinity during the
past 2,200 years, indicating fluctuations in effective moisture.