| Popis: |
Volcanic systems represent a fundamental component of the neovolcanic zones in Iceland. They are composed of a central volcano and a fissure swarm, or a combination of the two. The 2014–2015 rifting event at the Bárðarbunga volcanic system produced basaltic lava approximately 40 km to the north of the central volcano, within a fissure swarm commonly attributed to the Askja volcanic system, highlighting the complex tectonic structure of a region, directly above the Iceland mantle plume. New analyses of Sr- and Nd-isotope ratios from the new lava (Holuhraun), and the underlying older Holuhraun lava, show that they have identical values to those of the Bárðarbunga-Veiðivötn lavas and tephra erupted during the Holocene. Moreover, comparison with published high-precision radiogenic isotope data, reveals that Holocene lavas and tephra from the Bárðarbunga and Askja systems are characterized by contrasting Sr- and Nd-isotope ratios, with the notable exception of the Þjórsárhraun lava and two early Holocene lavas from the extreme west and east of the Veiðivötn fissure swarm. The $^{87}$Sr/$^{86}$Sr and $^{143}$Nd/$^{144}$Nd isotope ratios can thus be utilized to define the provenance of lava flows north of the Vatnajökull ice cap, ascertaining that the large lava fields of Krepputunguhraun and Fjallsendahraun (Frambruni) must also have originated within the Bárðarbunga volcanic system. |
