Kinematics and Heat Flow in a Volcanic Rift Zone, with Application to Iceland

Abstract

A kinematic model of a volcanic rift zone, based on plate tectonics concepts of crustal accretion, is presented. Quantitative relationships between observable parameters of the model are tested by a comparison with estimates from Iceland of the rate of production of extrusive rocks by eruptions, the width of the volcanic zone, the drift velocity of the lithospheric plates, the regional dips of the flood basalts and the rate of increase of dyke volume fraction with depth in the eastern Iceland lava pile. Approximate calculations of surface heat flow in the volcanic zone of the model and the adjacent lithospheric plates have been made and compared with heat flow observations from various parts of Iceland. The model appears to describe fairly well certain regional structural properties of the Icelandic lava pile, such as regional dips of the flood basalts and the average dyke distribution with depth. It is also compatible with the general pattern of heat flow values in Iceland. It is necessary, however, to assume that crustal accretion has shifted between at least two zones during the time involved in building up the Icelandic lava pile.