A deep seismic reflection profile over a Caledonian granite in central England

Abstract

In 1980, a short, deep reflection profile, undertaken jointly by the University of Leicester and the Institute of Geological Sciences, crossed a buried Caledonian granite to the south-west of Melton Mowbray in Leicestershire. Little structure is seen in the section between the top of the granite at 0.25 s two-way time (sTWT), and a zone of very strong sub-horizontal reflections at 6 s TWT. A further reflection zone is identified at 7.2s TWT below which there are a series of strong but impersistent reflections to the full reording time of 12 s TWT. The data indicate that the granite must be relatively homogeneous and underlain by several marked sub-horizontal boundaries at mid- to lower-crustal levels. This suggests that, during emplacement, either the granite must have had little effect on the lower crust sampled by the profile, or the lower crust was mobile enough to have developed layering since the granite was emplaced during the Caledonian orogeny.