Depth Extent - An Overlooked Parameter in Magnetic Depth Estimation

Magnetic depth estimation has been an essential component of geophysical interpretation since its earliest days. Virtually all depth estimation techniques are based in some measure on determining curve characteristics of relatively simple body geometries such as infinite dikes, contacts and thin plates. Such techniques worked reasonably well in continental areas of thick crust and relatively shallow basins. However, as exploration has moved into the offshore and other remote areas where basins are extremely deep and correspondingly the crust is significantly thinner, these methods tend to break down and yield depth estimates which are generally much too shallow because the assumed infinite thickness model doesn’t fit the geology. We present modeled results to demonstrate the thickness effect, develop corrections to account for these effects and demonstrate the value of these corrections in improving the results on simple models.