E-Poster Images Offer Wide View

3-D Gulf Tour

If a mere picture is worth a thousand words, a suite of 3-D images is perhaps comparable to encyclopedic in the value of the message it conveys.

It takes only a few choice words, however, to characterize the visual impact of certain 3-D images, with "stunning" and "spectacular" often at the top of the list.

Such was the case with the graphics accompanying the presentation "Evolution of the Northern Gulf of Mexico Through the Cenozoic — A 3-D Visualization Tour," given at the interactive e-poster session at the AAPG Annual Meeting last month in Salt Lake City.

The array of vibrant images was proffered by Bill Galloway during his delivery of the paper, which was co-authored by Dennis A. Sylvia and R. Combellas. The trio is based at the Institute for Geophysics, University of Texas at Austin.

Probably the most dramatic 3-D aspect of the presentation was a series of surfaces that basically reflect a quantitative paleobathymetry of the subject region, which was contoured as a derivative of the standard paleontologic-base depth zonation.

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If a mere picture is worth a thousand words, a suite of 3-D images is perhaps comparable to encyclopedic in the value of the message it conveys.

It takes only a few choice words, however, to characterize the visual impact of certain 3-D images, with "stunning" and "spectacular" often at the top of the list.

Such was the case with the graphics accompanying the presentation "Evolution of the Northern Gulf of Mexico Through the Cenozoic — A 3-D Visualization Tour," given at the interactive e-poster session at the AAPG Annual Meeting last month in Salt Lake City.

The array of vibrant images was proffered by Bill Galloway during his delivery of the paper, which was co-authored by Dennis A. Sylvia and R. Combellas. The trio is based at the Institute for Geophysics, University of Texas at Austin.

Probably the most dramatic 3-D aspect of the presentation was a series of surfaces that basically reflect a quantitative paleobathymetry of the subject region, which was contoured as a derivative of the standard paleontologic-base depth zonation.

"It was with a fair bit of effort that this was converted into an actual pseudo-bathymetric map," Galloway noted.

The material he presented at the e-poster gathering was an outgrowth of an industry consortium called the Gulf Basin Depositional Synthesis project, which originated seven years ago.

"During the first two phases of the project, we created a digital GIS database and used this to create suites of maps, primarily for our supporting companies," Galloway said. "But Phase 3, which ended six months ago, was different.

"We added new kinds of information," he said, "essentially creating a GIS database and synthesizing and consolidating interpretations for the Tertiary history for the whole Gulf basin — with emphasis on the U.S. half of the Basin — for the whole Cenozoic.

"One of the additions during Phase 3 was the compilation of paleobathymetric data, which were derived from micro-paleo reports collected over the years of OCS drilling.

"We hit on the idea of going beyond just creating a little quilt that used numerical zones from shallow to deep water, which usually means I to VI," Galloway said, "to attempting to convert this to actual depths.

"It was not easy."

'Some Interesting Things'

To accomplish this goal, Sylvia called on expertise he acquired as a meteorologist with the U.S. Air Force.

"Dennis was aware of the use of map algebra, which meteorologists do regularly with such things as pressure," Galloway said. "He did a lot of conditioning in the sense of establishing boundaries, e.g., shoreline locations, maximum depths for a paleo GOM, so we could put boundaries on the basin."

"We extracted in a selective way the paleobathymetry information for each stratigraphic unit that the database differentiated from a very large database released by the MMS," Galloway noted, "which includes paleo reports from more than 10,000 wells in the OCS."

Paleobathymetric surfaces were constructed for 13 time steps during the Cenozoic. The reconstructions show how 3-D visualization can be used to evaluate the impact of events such as continental climate change and tectonics on the sedimentation history of the Gulf basin.

Bathymetric surfaces were modeled for each of the major Oligocene and younger depositional episodes. Doppler maps were also constructed depicting depositional pattern change.

"Geologically, you see some interesting things going on, and some surprising things are highlighted when you look at the map as a 3-D rather than just color blotches," Galloway said.

"And likewise, when you subtract and look at a map that shows change through time rather than a condition that exists at a particular interval of time."

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