Constructing a crustal-scale 3-D earth model of offshore-to-onshore western Newfoundland using seismic reflection, seismic refraction, gravity and magnetic data

Abstract

Western Newfoundland is characterized as a geologically complex region for which the potential field data have not been incorporated into tectonic models. To this end, a 3D density model of Western Newfoundland was constructed by means of forward gravity modelling and gravity inversion to better understand the complexity of the Appalachian structures on which Western Newfoundland is placed. This model was constrained by seismic refraction and seismic reflection data located in the study area, and surface geology. Density values were calculated from empirical velocity-density functions and gravity forward modelling adjustments. The 3D density model, 3D gravity inversion results, and magnetic data support the presence of a high density lower crustal body in the Grenville Province. It is possible that this particular body may extend further north and could be related to the denser body found in southeast Labrador. The high resolution magnetic map for the study area showed two WNW-ESE linear magnetic anomalies in the Gulf of St. Lawrence that lie perpendicular to the Newfoundland coast. They could be explained by the presence of ancient inherited basement involved transfer faults that resulted from offset ancient ridge axis segments during the opening of the Iapetus ocean.