Virginia Tech geological sciences doctoral student Thomas Wynn is mapping the layers of rock from the Mississippian age across the entire state. He has two goals. One is to find and map oolites within the carbonate-siliciclastic layer of rocks known as the Greenbrier Group. Oolites often contain natural gas. His second aim is to better understand the transition from greenhouse conditions similar to today's climate to global ice-house conditions - one of the most extreme ice age in Earth's history.
Wynn will present his completed map at the Geological Society of America's 114th annual meeting in Denver, Oct. 27-30.
As companies have drilled for oil over the years in West Virginia, they collected the chips that the drills brought up, noting each 5- or 10-foot interval. The West Virginia Geological Survey has preserved these well cuttings. Wynn is now using well cuttings from 200 wells to create a three dimensional map of the state's subsurface. In effect, he is connecting the dots between the wells.
"If you were at the beach and observed the ground as you walked in a straight line from the dunes to the ocean's edge, you would have little idea of the complexity of the area. You need to also walk up and down the beach at different distances from the ocean, for instance."
Wynn has located significant oolites. "There are pretty good reservoirs of natural gas in West Virginia -- and throughout the United States," he says. But to access the reservoirs, drillers need to understand the rock. "The oolite is not uniform; its locations are controlled by faults and other topographic highs, or high areas."
Previous researchers have located the faults but did not document their influence on the deposition of oolite.
In addition to the map for the GSA presentation, Wynn is inputting his findings into a GIS database that others will be able to use on different computing platforms.
What about that climate change? "The Mississippian Age, from 335 to 327 million years ago, was an important time in world history. There was a major climate change on earth," Wynn says. "Little is know about how carbonate systems or any system reacts to such changes."
Carbonate rocks are those that are formed from carbon-based or biological materials. Clastic rocks are formed by water erosion of older rock. "During the time of deposition of the Greenbrier, as we go from older to younger material, we can see the rock change from carbonate to clastic. So the climate went from dry to wetter. The question is, what was the influence of tectonics -- the movement of the plate from 25 degrees south of the equator and subsequent climate change? And what was the influence of the ice age and the forming, melting, and reforming of ice caps with subsequent changes in ocean levels? In addition to the complex influence of tectonics, we are seeing wet to dry shifts with the waxing and waning of glaciers. Hopefully my study will be able to answer some of these questions."
The poster, "Eustasy and tectonics of a Mississippian carbonate ramp, West Virginia, USA," will be presented from 8 a.m. until noon on Oct. 27 in the Colorado Convention Center Exhibit Hall. Virginia Tech geological sciences professor J. Fred Read is co-author.
Wynn, who is from Mebane, N.C., received his undergraduate degree from the University of North Carolina at Chapel Hill and his master's degree from Old Dominion University, Norfolk, Va.