Published online by Cambridge University Press: 06 July 2012
A Summary is given of the field relations, geographical distribution and petrography of twenty-nine dolerite plugs associated with the Tertiary lava plateau of north-east Ireland. All but two of the plugs are composed of olivine dolerite. The exceptions are a pyroxene-rich dolerite and a tholeiitic type containing abundant chlorophæite. Trace-element determinations have been made on specimens from thirteen of the plugs.
Slight but definite chemical differences are shown to exist between the olivine-dolerites and the average Tertiary olivine-basalt lava of the area. The petrogenetic relationships of the two are briefly considered.