As part of the regional synthesis phase of the proposed Ocean Margin Drilling Project, magnetic and gravity anomaly maps of the central and western Gulf of Mexico have been prepared from existing data, many of which have not been previously processed or interpreted.

Magnetic anomalies, derived by removal of the modified 1975.5 IGRF and average diurnal variation, are of relatively small amplitude, generally ±50 to 100 gammas, with wavelengths on the order of 50 to 200 km. Free air gravity anomalies have typical amplitudes of ±30 milligals and wavelengths of 50 to 200 km.

Distinctive linear magnetic and gravity anomalies parallel the northwest (Texas) Gulf Coast and the northwest margin of Campeche Bank. Such anomalies are poorly developed along the margins of the Bay of Campeche.

Over the central Gulf, low-amplitude linear magnetic anomalies are present. These anomalies are consistent both in trend and apparent offset with predictions based on hypothetical formation of the Gulf by sea-floor spreading synchronous with early opening of the central North Atlantic. Modeling of these anomalies and calculation of magnetic depth-to-source are in progress and should provide better insight into the origin of the Gulf of Mexico.

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