The eastern Great Basin thrust belt provides an opportunity to explore for giant oil and gas fields. Thick, thermally mature, organic-rich, lacustrine oil shales deposited in the Mississippian Antler Basin flood plain in eastern Nevada are the source beds for the fifty million barrels of oil already produced in Nevada. Some of the oil migrated into the newly discovered giant oil field in central Utah. Karsted unconformities, stromatoporoid reefs, impact breccias, and sandstones make the eastern Great Basin Devonian reservoir rocks most favorable for giant accumulations. One Great Basin well in the Grant Canyon field of eastern Nevada flowed 4,000 barrels a day for ten years from these karsted carbonates. Late Cretaceous thrusting created the compressional features of the prolific Canadian foothills, Utah/Wyoming thrust belt, the new central Utah oil field, and the eastern Great Basin thrust belt.

A deeply entrenched notion that discouraged exploration investment is that the north-south structural grain of the eastern Great Basin was caused by Tertiary extension that could have compromised seals on older, compressional structures.The newly discovered giant oil field on the eastern edge of the Great Basin provides an example of an intact compressional feature. Another example of an intact compressional feature is the Golden Gate fault fold 40 miles south southeast of the prolific Grant Canyon field and 120 miles north of Las Vegas. The Golden Gate fault fold is ten miles long and five miles wide and has more than five thousand feet of closure. It may have trapped billions of barrels of oil before it was breached by headward erosion of the Colorado River. New mapping reveals that no Tertiary extensional faults compromise the structure. Similar structures, along strike that have escaped erosion, likely contain billions of barrels of oil and trillions of cubic feet of gas such as the newly discovered giant Utah oil field. Oil seeping from these giant fields is probably the source for the Great Basin commercial oil seep fields. However, old opinion and theories based on little or poor geologic mapping have obscured the true understanding of the eastern Great Basin geology for at least five decades. As a result, past oil exploration efforts in the eastern Great Basin based on old tectonic and depositional models have been disappointing.

BIOGRAPHY

Alan K. Chamberlain, Ph.D., President of Cedar Strat Corp. (775) 237-5076. Alan K. Chamberlain received his B.A. and M.S. from Brigham Young University and his Ph.D. from Colorado School of Mines. His dissertation, Structural Geology and Devonian Stratigraphy of the Timpahute Range, Nevada, provides a new exploration model that could lead to significant discoveries in this frontier region. After he worked for Exxon, Gulf, Marathon, and Placid, he became president of Cedar Strat Corporation in 1984. Constrained by well data, measured sections, and new gravity surveys and geologic maps, Cedar Strat has identified 36 Great Basin structural plays similar to the giant discovery in central Utah.