The geochemistry of four icelandic basalts.

The geochemistry of four Icelandic basalts is compared with that of other basalts along the Mid-Atlantic Ridge. The lava from Beruvikurhraun is the only alkali basalt. It has the high Ba and Sr concentrations typical of alkaline rocks. The other three basalts are tholeiites ranging from 49.00 to 50.42 per cent SiO2 and 0.22 to 0.54 per cent K2O. In their overall major element chemistry, the Icelandic basalts resemble the Hebridean basalts and Nockolds' average tholeiite. They are more iron rich than average basalts from other localities along the Ridge. A parent magma of a composition similar to the average Hawaiian tholeiites (MACDONALD and KATSURA 1964) could give the high iron, low magnesium basalts of Iceland by early separation of olivine (forsterite). Crustal contamination through any process we know of today is not consistent with many aspects of the chemical composition of the rocks, both with regard to major and trace elements.