Update on the cosmogenic in situ 14C laboratory at the Lamont-Doherty Earth Observatory
Published on Oct 1, 2019in Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms1.21
· DOI :10.1016/j.nimb.2019.05.064
Abstract Cosmogenic in situ 14C in quartz is rapidly becoming a widely used geochronological tool for studying earth surface processes over the last 30,000 years. The Lamont-Doherty Earth Observatory houses one of the longest continuously-operating cosmogenic in situ 14C laboratories; in this contribution, we provide an update on the status of the laboratory following Goehring et al. (2014). From 2010 to the present, our long-term average blank value is 119,000 ± 37,000 14C atoms, with no statistically significant trend over the last nine years. While our average measured 14C concentration of the CRONUS-A inter-laboratory comparison standard is in line with data published from other laboratories, we note a step increase between 2013 and 2015 that is still under investigation. Additionally, we report our first procedural blanks and CRONUS-A values analyzed on the gas source of the AixMICADAS at CEREGE, France. Many of the >75 samples analyzed at Lamont for in situ 14C from the Arctic, Antarctic, New Zealand, and the Alps have been paired with 10Be analyses contributing to the increasing density of burial dating data covering the last 20,000 years. Currently we are working on increasing sample throughput, streamlining the 14C extraction procedure, and considerably decreasing blank levels.