HIGH-RESOLUTION DATING OF LATE HOLOCENE PALEOCLIMATE RECORDS FROM THE WESTERN USA USING PALEOMAGNETIC SECULAR VARIATION RECORDS FROM SEDIMENTS, LAVAS, AND ARCHEOLOGICAL MATERIALS

A new composite paleomagnetic secular variation (PSV) record spanning the last 3000 years has been developed for the western USA. This composite PSV record is very well dated (±50-100 years resolution) and corroborated using a mixture of radiocarbon dating, archeological contexts, and tree ring dating. Another twelve individual sediment PSV records from the western USA (that also contain high-resolution paleoenvironemntal information) have been individually correlated with the new composite record by identifying a series of PSV features common to almost all of the records. These PSV correlations identify where systematic radiocarbon dating errors due to reservoir effects or addition of ancient carbon are present in the twelve individual PSV records. Revised chronologies were developed for these records based on PSV feature ages noted in our new composite PSV record. The revised chronologies for these twelve sediment records provide a significantly better time scale for correlating, on a regional scale, paleoenvironmental fluctuations noted at each site than was possible before. This technique offers the potential to assess the potential synchroneity (±50-100 year resolution) of paleoenvironmental signals on a regional scale (ca. 4000 km)for the entire Holocene (and longer) of the western USA.