Removing Unwanted Edges from Gravity Datasets

Gravity data is widely used in the search for mineral deposits, and may be collected on the ground or by airborne platforms. The boundaries between rocks with differing densities result in boundaries in their corresponding gravity anomalies. These boundaries, or edges, can be located using techniques based on horizontal derivatives of the data. High resolution data can possess a proliferation of such edges, making interpretation difficult. While smoothing can be applied to reduce the number of edges, it has the disadvantage that the remaining edge locations are changed and the shape of the edge contours is altered. Three methods are compared here for the removal of unwanted edges which may be due to noise and which can make interpretation difficult. The first method removes edges which are not present in the data after its upward continuation to a user-selected height. The second method removes edges whose amplitude is below a given threshold, and the final method removes the smallest edge contours. All three methods have different strengths and weaknesses.