Plant radiocarbon ages and rock surface cosmogenic 14C inventories collected at retreating ice cap margins on Baffin Island, Arctic Canada, 2013

These two data sets contain the results of quantitative radiocarbon measurements in in situ tundra plants and in rock surfaces collected near dated plants, both collected close to the margins of ice caps on Baffin Island, Arctic Canada. Repository 1 provides radiocarbon measurement results for in situ plants that had been entombed beneath cold-based ice. The primary data are conventional radiocarbon ages, their calibrated ages using Northern Hemisphere IntCal13, each with one sigma uncertainties, their geographic coordinates (±10 m) and sample elevation (±20 m), both derived from hand-held GPS units. We interpret the calibrated ages to define with the plants were killed. Repository 2 contains the locations of sampled un-eroded rocks collected close to 14C-dated in situ plants, and the in situ cosmogenic 14C concentrations measured in those rock surfaces. We interpret the 14C inventories to reflect 14C production from cosmic rays when the rocks have been exposed without any ice cover, as well as 14C production at lower rates when the rocks were covered by <30 m of ice, both balanced by the decay of 14C since its production.

本数据集包含两类样品的定量放射性碳测量结果：一类为原位（in situ）苔原植物，另一类为采集自经定年植物附近的岩石表面样品，所有样品均采集自加拿大北极地区巴芬岛的冰盖边缘区域。数据存储库1（Repository 1）提供了被封存于冷底冰下方的原位苔原植物的放射性碳测量结果，其基础数据包括常规放射性碳年龄、采用北半球IntCal13校正曲线得到的校正年龄（均附带1σ误差限）、地理坐标与样品海拔高度，其中坐标与海拔均通过手持GPS设备获取，坐标精度为±10米，海拔精度为±20米。本研究通过上述校正年龄推断植物的死亡时间。数据存储库2（Repository 2）收录了采集自经¹⁴C定年的原位植物附近的未侵蚀岩石采样点位，以及这些岩石表面测得的原位宇宙成因¹⁴C浓度。本研究认为，¹⁴C储量可反映两种情形下的¹⁴C生成量：一是岩石完全无冰覆盖时，宇宙射线引发的¹⁴C生成；二是岩石被厚度小于30米的冰体覆盖时的低速率¹⁴C生成；上述两种生成过程均与自生成以来的¹⁴C衰变过程达到动态平衡。