Gulf Coast Examples of the Regional Perspective of Local Structure Gained by the Analysis of Near-Surface Magnetic Responses

John Land¹, Robert Van Nieuwenhuise², Lawrence A. Jamison³, and Mohammed Kidwai^4
1JP Land Associates, Inc., Houston, TX
²Earth-Wave Geosciences, LLC, Fulshear, TX
³Consultant, Cypress, TX
⁴GETECH, Inc., Houston, TX

When high resolution aeromagnetic surveys are flown at a low terrain clearance on a tighter survey grid, we're able to record the entire frequency range of the magnetic field. When such data is thoroughly analyzed it allows an interpretation of the structuring of the sedimentary section, top to bottom, near-surface to basement. The intent of this paper, by presenting a regional sampling of near-surface magnetic anomalies in the Texas Gulf Coast and the new evidence their trends develop regarding the region's tectonics, is to demonstrate the ability of High Resolution Airborne Magnetics to provide the structural geologist an improved perspective of a region's structural grain and possibly, some idea of the most likely structural cause of a particular near-surface anomaly.

The paper will include a brief discussion of the cause and recognition of near-surface magnetic anomalies and compare the near-surface picture to the subsurface geology and the deep-structure interpretation of the magnetic data. Examples are from an ongoing regional study of three separate areas of the Lower, Middle and Upper Gulf Coast of Texas which include the Transition Zone.

Near-surface magnetic anomalies, considered to be evidence of shallow structuring and therefor potentially prospective, are often present on the flanks of salt domes. When other types of data, geological, geophysical and/or geochemical show anomalies coincident with such a feature, it is then considered an excellent and worthy target for a specific 3D seismic investigation. Examples of this cross-correlation are to be part of the presentation.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas