GMAP v.32: Geographic mapping and palaeoreconstruction package

Abstract

GMAP is a state of the art computer which performs all processing and plotting tasks usually associated with the storage and presentation of palaeomagnetic pole positions, and generation of palaeographic reconstructions. One of GMAP's special features, which places is ahead of other software of its type, is a built-in, statistically robust, method for fitting smooth curves to weighted palaeomagnetic pole position. GMAP is menu-driven and very easy to use; the user is never far removed from the basic data from which palaeogeographic reconstructions are derived, and therefore has a sense of total control over the program's performance. GMAP can generate reconstructions based on individual palaeomagnetic poles, averages palaeomagnetic poles and digitally derived smooth (APW) curves. The user is also free to simply move continents around on the screen, according to less tangible constraints. Palaeogeographic reconstructions can be saved to disk files, and later viewed in chronological order as 'animations'. GMAP is supplied with a full range of continental outlines. These continents may be edited, split or combined to suit the user's personal requirements. It is also possible to import new continents with simple ASCII files or to import continents from the Palaeomap project. An ATLAS of reconstructions (Torsvik & Eide 1998) id included in the system. GMAP can also calculate plate-speeds (minimum), angular rotations and rates of APW based on APW parths. It also contains routines to estimate magnetic polarity bias and the most recent compilations of magnetic polarity data are included with the system. GMAP is in use at leading institutions world-wide, and has been the 'work horse' of EGT and EUROPROBE projects. GMAP also interfaces with the Global Palaeomagnetic Data Base.