Major and trace element analysis of lavas from eastern Iceland

This dataset consists of the major and trace element lava analysis from appendices 4 and 5 from the PhD thesis: <b>The Petrology and Geochemistry of Tertiary Lavas from Eastern Iceland</b>. By David A. Wood. Awarded by Imperial College of Science and Technology (University of London, United Kingdom) in November 1977Abstract: Major and trace element analyses are presented for 162 basaltic samples from the Tertiary (approximately 13 to 2 Ma) lava pile. Additional analyses are included for silicic and intermediate lavas, from the central complexes within the lava pile, and representative basaltic lavas from elsewhere in Iceland. The petrography and microprobe analyses of the phenocrysts are reported, together with the chemistry of the secondary minerals, and factors controlling their formation and distribution. The mobility of K, Rb, Sr , Ba, La, Ce and Th during zeolite grade metamorphism is indicated from analyses of multiple samples from single lavas, which are used to assess the contribution of magmatic, deuteric and hydrothermal processes to chemical variation within lavas.Lava chemistry is considered in terms of crustal structure and the episodic nature of eruptive processes in Iceland. Chemical zonation of eruptive units is established with the lithophile-element-poor basalts, restricted to the marginal regions of the units. Subsidence in the axial regions of the eruptive units results in a vertical chemical zonation of the lava pile . Subsequent erosion leads to spatial chemical variation on the exposed land surface . Chemical differences between the Mg-rich basalts are described and comparisons with basalts from other areas of crustal extension are made.A model invoking the derivation of non-basaltic lavas from a lithophile-element-rich, parental basalt by fractional crystallisation of the observed phenocryst proportions is proposed on the bases of: (1) major and trace element variation diagrams; (2) least-squares solutions for the major element oxides; (3) Rayleigh fractionation solutions for the rare earth elements; and (4) the inadequacies of other models. The importance of apatite and iron-titanium oxides fractionation in controlling the chemical evolution of the residual liquid during crystal fractionation is a characteristic of the model.<br>