Chronologies for Recent Peat Deposits Using Wiggle-Matched Radiocarbon Ages: Problems with Old Carbon Contamination

摘要: Dating sediments which have accumulated over the last few hundred years is critical to calibration of longer-term paleoclimate records with instrumental climate data. We attempted use wiggle-matched radiocarbon ages date 2 peat profiles from northern England high-resolution paleomoisture variability ~300 yr. A total 65 14C accelerator mass spectrometry (AMS) measurements were made on 33 macrofossil samples. number age estimates older than expected and some oldest occurred in upper parts sequence, had been dated late 19th early 20th century using other techniques. suggest that are result contamination by industrial pollution. Based counts spheroidal carbonaceous particles (SCPs), potential aging effect for SCP carbon was calculated shown be appreciable samples century. Ages corrected this still too old cases, could a fossil CO2 fixation, non-SCP particulate carbon, due imperfect cleaning samples, or "reservoir effect" fixation emanating deeper layers. Wiggle matches based overall shape depth-14C relationship minima curve identified. These tested against (210Pb, pollen, SCPs) provide new age-depth models profiles. New approaches needed measure impact industrially derived recent sediment more secure chronologies years.