Publication 22

Prelimenary interpretation of the upper crustal structure beneath Prince Edward Island

Alan G. Jones and G.D. Garland

Abstract

A reconnaissance magnetotelluric survey of Prince Edward Island was undertaken during 1983 to aid in the assessment of the geothermal energy potential of the province. At ten locations, measurements were made in the period range 0.0026-1820 s, and, in general, the data quality was very high. Beneath the whole of the Island, to a depth of around 200-600 m, is a moderately resistive zone of some 150 ohm.m. Underlying this is a highly conducting zone of 10 ohm.m down to 1250 m at the most north-westerly point, and to about 3000 m beneath the centre of the eastern part of the island. This layer can be associated with shale sequences found by drilling. Beneath these shale sequences, there is a dramatic difference in rock type for the western, compared to the eastern, part of the island. Underlying the eastern half, at depths of some km, is a moderately resistive sedimentary sequence of around 150 ohm.m. For the western part of the Island there is a resistive zone which can be identified from the borehole logs as pre-Carboniferous bedrock. The topography of the upper surface ofthis resistive zone is shown to be consistent with the known gravity anomaly in the region.

Source

Annales Geophysica, 4B, 157-164.

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Alan G Jones / 28 February 2010 / alan-at-cp.dias.ie