3-D constrained inversion of gravimetric data to map the tectonic terranes of southeastern Laurentia using simulated annealing

Abstract

Abstract Inversion of gravity anomaly data can be an effective tool in reconstructing the geologic history of a region by segregating tectonic terranes with different physical properties. Recent advances in computational capabilities coupled with lithospheric-scale seismic experiments provide the opportunity to conduct 3D regional-scale, constrained inversions of gravity data using global optimization algorithms. Here, a method for inverting gravity anomaly data by combining a finite-element method based forward calculation with a simulated annealing algorithm is introduced. The method is applied to the southeastern Laurentia region, which is comprised of an amalgamation of crustal blocks spanning a tectonic history of over 1.5 Ga. The method better defines the gross crustal density distribution of the region, and proves to be efficient in spatially discriminating between the different tectonic terranes. The tectonic terranes fall within four distinct groups, based on the average crustal density, each of which seem to have undergone a distinct geologic history.