Lithospheric density variations and Moho structure of the Irish Atlantic continental margin from constrained 3-D gravity inversion

摘要

A 3-D density anomaly model of the Irish Atlantic continental margin was generated from audregional inversion of the free air gravity data constrained by bathymetric and sediment thicknessudinformation. The model results are compared against a recent regional Moho structureudcompilation from velocity models from crustal-scale wide-angle reflection/refraction surveys.udUsing the inverted model, a regional map of Moho structure across the margin agrees well withudthe regional seismic compilation and also provides information in areas lacking deep seismicudcoverage. The density anomaly structure of the crust across the margin is investigated alongudmodel slices and using volume rendering of crustal layers. These views reveal extreme thinning,of the upper crust and a dominance of lower crustal densities in regions where exhumation of,serpentinized mantle has previously been interpreted. Using the regional view afforded by, the,inversion, the areal extent of these zones is tracked into regions lacking seismic constraints.udUsing the regional density anomaly model, variations in sediment thickness and crustal thicknessudare investigated to compute stretching factors across the margin and to identify zones,which deviate from local isostatic compensation. These zones generally correlate with faults,and rifting trends providing insights that could be useful for future palaeoreconstructions ofudNorth Atlantic rifting.