Magan: A new approach to the analysis and interpretation of marine magnetic anomalies

摘要

The identification of marine magnetic anomalies is an important phase of plate tectonic modeling, but is limited by the lack of professional software, either free or commercial, which may help in the accomplishment of this task, and by the practice of performing approximations that may prevent in some instances a correct interpretation of the magnetic data. Although basic forward-modeling and inversion algorithms that may be incorporated in the core of gravity or magnetic application software have been published since the late 1950s, most research groups have implemented their own tools independently from each other, and apart from a few cases such computer programs are not publicly accessible. Here a new methodology of analysis of marine magnetic data is described, which allows a quantitative correlation of magnetic anomalies from different profiles and a statistical determination of relative plate velocities. The method is implemented through a new free software package, Magan, available for the MS Windows environment. The program is especially designed to work with NGDC GEODAS ship-track and aeromagnetic data, but allows the import of any ASCII text file containing magnetic anomaly data. The basic forward-modeling algorithms included in the Magan core are based on well-known techniques of potential field geophysics, modified to take into account specific requirements of marine magnetic data analysis and plate tectonic modeling. Such a kernel is flanked by a friendly graphical user interface (GUI), which helps and speeds up the interpretation of the ship-track data. In particular, the program allows one to (1) draw and edit flow lines where magnetic data can be projected, (2) calculate more accurately modeled anomalies through the use of apparent polar wander paths and single block parameters, (3) generate age-distance and time-velocity graphs, and (4) generate crossing point files that can be subsequently used to build magnetic isochrons.