Δ14C PEAKS APPEARING IN EARLYWOOD AND LATEWOOD TREE RINGS (AD 770-780) IN NORTHEASTERN ARIZONA

The AD 775 peak in Delta C-14 (henceforth, M12) was first measured by Miyake et al. and has since been confirmed globally. Here we present earlywood and latewood Delta C-14 values from tree rings of pinyon pine (Pinus edulis) from Mummy Cave, Canyon de Chelly National Monument, Chinle, Arizona, USA, for the period AD 770-780. These data reconfirm the timing of M12 and show a small rise in Delta C-14 in AD 774 latewood. Allowing for the delay in lateral transfer of radiocarbon produced at high latitude, this suggests that C-14 peak production occurred in late winter or spring of AD 774. Additionally, Delta C-14 decreased slightly in the earlywood of AD 775 and increased in the latewood of AD 775 to a higher level than that observed in AD 774.

Automated summary

The study reconfirmed the AD 775 peak in ΔC-14 through tree ring data of pinyon pine in Arizona, USA. Results showed a slight rise in ΔC-14 in the latewood of AD 774, a slight decrease in the earlywood of AD 775, and an increase in the latewood of AD 775 to a higher level.