Evolution of the northern Gulf of Mexico, with emphasis on Cenozoic growth faulting and the role of salt

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Abstract The northern Gulf of Mexico Basin, although one of the most intensely studied and explored regions in North America, is also one of the most structurally complex (Figs. 1 and 2). Cenozoic depocenters contain abundant growth faults of a variety of shapes, orientations, sizes, and complexities. In addition, salt domes, flows, and massifs combine to form a complex near-surface pattern that tends to mask the origins of many structures. Not surprisingly, a number of contrasting hypotheses have been proposed to explain the growth faults of this region, among them theories invoking shale diapirism, shale compaction, gravity gliding, salt diapirism, and salt flow. Clearly, the best way to understand the various origins of these features is to observe their structural underpinnings at depth; unfortunately, most of the large growth fault systems of the Texas and Louisiana shelf project below the bottoms of seismic lines of 6- or 7-sec record length. However, as will be discussed in this chapter, deep seismic data now available from the Louisiana slope greatly illuminate the spectacular structural development of this province. In addition, palinspastic reconstructions are useful for analyzing the structural development of these features, and for constraining hypotheses on their origins. Prior to discussing the Cenozoic tectonic development of the northern Gulf of Mexico—the main focus of this chapter—we will briefly review the pre-Cenozoic framework and basic Cenozoic depositional patterns of the Gulf of Mexico Basin, both of which influenced Cenozoic structural styles. The Gulf of Mexico Basin (Fig. 1) was initiated in the late Middle to early Late Jurassic as a result of crustal attenuation and sea-floor spreading associated with the breakup of the supercontinent Pangea.