Paleoclimate of the past 4000 years at Lake Turkana, Kenya, based on the isotopic composition of authigenic calcite
Abstract Authigenic calcite was analyzed for δ 13 C and δ 18 O in a 12 m long core from Lake Turkana that spans the last 4200 yr. The δ 18 O record is interpreted to reflect lake level history, and indicates high stands prior to 4000 yr B.P., from 1800 to 2000 yr B.P., and within the last century. This coincides better with the history of lake level change reported for other lakes in africa than did the previous lake level curve for Lake Turkana based on 14 C dates of exposed shoreline deposits. The δ 13 C curve roughly parallels the δ 18 O curve, and may reflect the influence of the Omo River plume. Both of the isotope records are strongly cyclic, with periodicites common to both at 80, 120, 150 and 225 yr. Other, somewhat longer periodicites are nearly equal in the two records, and there is close agreement with previously published cycles based on carbonate and lamination thickness analyses in the same Turkana core.