Speleothem carbon isotopic records of Holocene environments in the Ozark Highlands, USA

The carbon isotopic compositions of six stalagmites from five caves in the Ozark Highlands of central and southern Missouri and northern Arkansas prov ide a detailed record of early and late Holocene vegetation dynamics. A rap id decrease in speleothem partial derivative(13)C values between similar to 9500 and similar to 8200 yr BP indicates a period of increased C3 vegetati on, suggesting cool and/or moist conditions relative to the earliest Holoce ne and the prairie-dominated middle Holocene. A second negative partial der ivative(13)C excursion from similar to 4500 to similar to 3000 yr BP interr upts a predominantly C4-rich middle Holocene prairie environment that becam e established at similar to 7500 yr BP. Speleothem mineralogical indicators of cave aridity do not support previous inferences of increased regional d ryness between 3800 and 3100 yr BP. (C) 2000 Elsevier Science Ltd and INQUA . All rights reserved.