Geochemical evolution of basaltic tuyas in Iceland during the last deglaciation.

摘要

Tuyas are subglacial volcanoes that preserve a unique history of the interplay between glaciation and hot spot volcanism in Iceland during the last deglaciation. Geochemical signatures in eruptive units of tuyas provide insight into the influence of deglaciation on mantle processes. We measured major and trace element concentrations and helium isotopes in samples from eruptive units of thirteen tuyas in Iceland, which have recently been determined from cosmogenic 3He surface exposure dating to have formed during the last deglaciation. All tuyas display temporal variations in geochemistry between eruptive units. Geochemical analyses of eruptive units reveal that individual tuyas are subject to crustal-level processes and source variation during emplacement. The geochemical signatures of eruptive units suggest that the degree of partial melting did not change significantly during tuya formation. Helium isotopic signatures suggest the geographic location of tuyas is an important factor for recording local mantle heterogeneity during emplacement.