Visualizing Seafloor, Seismic, Gravity and Magnetics Data in the Deepwater Gulf of Mexico Improves Understanding of Geohazards, Salt and Seeps

摘要

The seafloor of the deepwater Gulf of Mexico represents therncomposite effects of a wide range of driving forces thatrninclude salt, basement faults, fluid and gas migration,rndepositional lobes and erosional channels. To improve ourrnunderstanding of the processes that control the seafloor werncombine exploration geophysics, remote sensing, and datarnmore commonly associated with site surveys. Multi-channelrnseismic data (both 2D and 3D) can provide ‘big picture’rnconstraints on through-going structures and long-livedrndepositional/erosional environments. Gravity data, which canrnbe improved by better topographic corrections using seafloorrnbathymetry, can be used to evaluate the distribution and stylernof salt migration and basinal features. Magnetics data, in turn,rncan be used to define the location and orientation of basementrnlineations and structures. High resolution comprehensive mapsrnof the seafloor provide an accurate geologic ‘snapshot’, whichrncan be used to evaluate the relative contributions of thernvarious driving mechanisms.rnIn this paper we will present data from the AlaminosrnCanyon region of the deepwater Gulf of Mexico (Figure 1)rnthat demonstrates the value of this integrated approach.rnFeatures that will be illustrated include slope basins where werncan interpret the direction of salt withdrawal and movement,rnamalgamated salt keels created by converging salt tongues, asrnwell as salt extrusion ‘bulges’ and diapirs. We will show arncorrelation of seafloor exposed high angle tear faults withinrnthe allochthonous section and autocthonous basementrnlineations, and we will use the character of the tear faults torndemonstrate their sense of motion. We will illustrate seeprntargets and pock marks, and show canyons and slope failuresrndriven by both external (downcutting) and internal (seepagerninduced) mechanisms. Our objective in this presentation is torndemonstrate that an integrated approach to seafloor and subseafloorrngeology can improve exploration targets and betterrndefine geohazards.