摘要 : Walker Lake, a hydrologically closed, saline, and alkaline lake, is situated along the western margin of the Great Basin in Nevada of the western United States. Analyses of the magnetic susceptibility (chi), total inorganic carbon... 展开 Walker Lake, a hydrologically closed, saline, and alkaline lake, is situated along the western margin of the Great Basin in Nevada of the western United States. Analyses of the magnetic susceptibility (chi), total inorganic carbon (TIC), and oxygen isotopic composition (delta O-18) of carbonate sediments including ostracode shells (Limnocythere ceriotuberosa) from Walker Lake allow us to extend the sediment record of lake-level fluctuations back to 2700 years B.P. There are approximately five major stages over the course of the late Holocene hydrologic evolution in Walker Lake: an early lowstand (> 2400 years B.P.), a lake-filling period (similar to 2400 to similar to 1000 years B.P.), a lake-level lowering period during the Medieval Warm Period (MWP) (similar to 1000 to similar to 600 years B.P.), a relatively wet period (similar to 600 to similar to 100 years B.P.), and the anthropogenically induced lake-level lowering period (< 100 years B.P.). The most pronounced lowstand of Walker Lake occurred at similar to 2400 years B.P., as indicated by the relatively high values of delta O-18. This is generally in agreement with the previous lower resolution paleoclimate results from Walker Lake, but contrasts with the sediment records from adjacent Pyramid Lake and Siesta Lake. The pronounced lowstand suggests that the Walker River that fills Walker Lake may have partially diverted into the Carson Sink through the Adrian paleochannel between 2700 to 1400 years B.P. (c) 2006 Elsevier B.V. All rights reserved. 收起