Revised triangle R values for the Barents Sea and its archipelagos as a pre-requisite for accurate and robust marine-based C-14 chronologies

The calibration of marine 14C dates requires the incorporation of regionally specific marine reservoir offsets known as.R, essential for accurate and meaningful inter-archive comparisons. Revised, regional.R ('triangle.RR') values for the Barents Sea are presented for molluscs and cetaceans for the two latest iterations of the marine calibration curve, based on previously published pre-bomb live-collected and radiocarbon-dated samples (`.RL'; molluscs: n = 16; cetaceans: n = 18). Molluscan triangle.RR, determined for four broad regional oceanographic settings, are: western Svalbard (including Bjornoya), 61 +/- 37 14C yrs (Marine20), 94 +/- 38 14C yrs (Marine13); Franz Josef Land, 277 +/- 57 14C yrs (Marine20), 122 +/- 38 14C yrs (Marine13); Novaya Zemlya, 156 +/- 73 14C yrs (Marine20), 0 +/- 76 14C yrs (Marine13); northern Norway, 86 +/- 39 14C yrs (Marine20), 74 +/- 24 14C yrs (Marine13). Molluscan triangle.RR values are considered applicable to other marine carbonate materials (e.g., foraminifera, ostracods). Cetacean triangle.RR are determined for toothed (n = 10) and baleen (n = 8) whales, and a combined toothed-baleen group (n = 18): toothed, 161 +/- 41 14C yrs (Marine20), 1 +/- 41 14C yrs (Marine13); baleen, 158 +/- 43 14C yrs (Marine20), 8 +/- 41 14C yrs (Marine13); combined baleen-toothed whales, 160 +/- 41 14C yrs (Marine20), 4 +/- 49 14C yrs (Marine13). Where identification and separation of baleen and toothed whales is impossible the combined triangle.RR term may be used. However, we explicitly discourage the application of existing cetacean triangle.RR terms to other marine mammals. Our new.RR values are applicable for as long as those broad oceanographic conditions (circulation and ventilation) have persisted, i.e., through the Holocene. We recommend using the latest iteration of the marine calibration curve, Marine20, which seems to better capture the time-variant nature of R compared to Marine13. More.RL datapoints for both molluscs and cetaceans would improve the accuracy and precision of triangle.RR. In the meantime, our new triangle.R terms facilitate the calibration of marine 14C dates across the region, paving the way for meaningful and accurate late Quaternary histories and inter-regional comparisons.