Petrochemistry of the Gjلlp-1996 subglacial eruption, Vatnajِkull, SE Iceland

In October 1996 a subglacial fissure to the north of the Grimsvötn caldera in W-Vatnajökull produced about 0.4 km3 of Fe-rich basaltic andesite–icelandite—in an area characterized mostly by tholeiitic basalt. In this paper the chemical composition of volcanic systems in the region is discussed with the help of six new analyses and others from the literature, and a tentative model for their evolution is proposed, in which magma produced by the partial melting of a two-component mantle mixes with hydrous, silicic melt in the crust. The Vatnajökull 1996 magma belongs to a separate volcanic system, intermediate between Bardarbunga and Grimsvötn.