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DOI: 10.1191/0959683605hl828rp © 2005 SAGE Publications Comparison of varve and 14C chronologies from Steel Lake, Minnesota, USADepartment of Geology, University of Illinois, Urbana IL 61801, USA
CAMS, Lawrence Livermore National Laboratory, Livermore CA, 94551, USA; jiantian{at}uiuc.edu,fshu@life.uiuc.edu
Department of Geology, University of Illinois, Urbana IL 61801, USA; Department of Plant Biology, University of Illinois, Urbana IL 61801, USA; Program in Ecology and Evolutionary Biology, University of Illinois, Urbana IL 61801, USA; jiantian{at}uiuc.edu,fshu@life.uiuc.edu Annually laminated sediments (varves) offer an effective means of acquiring high-quality palaeoenvironmental records. However, the strength of a varve chronology can be compromised by a number of factors, such as missing varves, ambiguous laminations and human counting error. We assess the quality of a varve chronology for the last three millennia from Steel Lake, Minnesota, through comparisons with nine AMS 14C dates on terrestrial plant macrofossils from the same core. These comparisons revealed an overall 8.4% discrepancy, primarily because of missing/uncountable varves within two stratigraphic intervals characterized by low carbonate concentrations and obscure laminations. Application of appropriate correction factors to these two intervals results in excellent agreement between the varve and 14C chronologies. These results, together with other varve studies, demonstrate that an independent age-determination method, such as 14C dating, is usually necessary to verify, and potentially correct, varve chronologies.
Key Words: Varve chronology 14C chronology laminated sediment counting error varve-count adjustment palaeoclimate late Holocene Steel Lake Minnesota
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