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. 2022 Apr 29;1(2):pgac048. doi: 10.1093/pnasnexus/pgac048

Fig. 4.

Fig. 4.

Major and minor element analyses of volcanic glass shards identified in NGRIP 641.12 to 641.16 m and GISP2 774.53 to 774.78 cryptotephras (V2), compared to previous analyses of the QUB-1198 tephra (27), and the proximal volcanic glasses of deposits erupted during the caldera-forming Aniakchak II (62) and Minoan (Thera) eruptions (63). Black error bars represent 2 SDs of replicate analyses of the ATHOG MPI-DING (64) glass standard run alongside the NGRIP 641.12 to 642.16 m sample, whilst blue error bars represent 2 SDs of replicate analysis of the NMNH 72854 (65) glass standard run alongside GISP2 774.53 to 774.78 m. Full chemical datasets including secondary standards are provided in the Supplementary Material.