Gravity and magnetic studies of crustal structure across the Porcupine basin west of Ireland

Abstract

Gravity, magnetic and seismic data from a profile across the Porcupine basin are used to suggest a model for the crustal structure in the region. The 280 km long profile bears WSW off the southwest coast of Ireland, and overlaps partially with the COOLE 3A and 3B lines of Makris et al. [13]. The gravity data are processed to produce an isostatic residual anomaly which is then modelled by two-and-a-half dimensional methods using the seismic data to provide geometrical constraints. Similar modelling techniques are used for the magnetic data. The final model shows crystalline crust which thins from 28 km at the eastern end of the profile to less than 8 km beneath the central part of the basin. The thinned crust is intruded by dense magnetic bodies, whilst the eastern margin is underlain by a large low-density body which is assumed to be a granite. These new findings have parallels in other basins on thinned and rifted crust.