GLOBAL MAGNETIZATION MODELS WITH A-PRIORI INFORMATION

In an effort to explore the possible effects of change in integrated m agnetization at the continent-ocean boundary and to account for such e ffects in modeling, an inverse technique is developed which allows for the inclusion of a priori information in models of global crustal mag netization or susceptibility. This technique accounts for processing e ffects such as main and external field removal. An a priori model cons isting of an ocean-continent magnetic contract, oceanic topography, an d remanent magnetization in the Cretaceous quiet zones is constructed using equivalent source dipoles. Previous investigations using similar models utilize only forward modeling procedures. We show how this a p riori model can be modified so that the resulting computed field, afte r removal of spherical harmonics below some specified degree (''main f ield'' removal) and along track filtering (''external field'' removal) , matches that of the robust POGO-Magsat anomaly map in a least square s sense. The dependence of the final model on the a priori information is also investigated. Between degrees 20 and 60 the final models are found to be almost identical for reasonable a priori conditions. An ex ample from the Gulf of Mexico and surrounding Gulf Coast region serves to illustrate the utility of the technique. High heat flow, > 400 C/k m, is observed in much of the Gulf Coast region. The example suggests that the elevated heat flow persists at depth and has elevated the Cur ie point.