ABSTRACT: Oil and Gas Exploration of the Central Nevada Thrust Belt

CHAMBERLAIN, ALAN K., Cedar Strat Corporation, Hiko, NV, DIETRICH ROEDER, Anschutz Corporation, Denver, CO, and RANDY L. CHAMBERLAIN,* Consultant, Littleton, CO

Structural analysis of the Cretaceous age Cordilleran Central Nevada fold-thrust belt (CNTB) is the key to locating structures that may hold much of Nevada's untapped oil and gas reserves. Thrusting created imbricate or duplex stacks of Devonian carbonate reservoir rock and organic-rich Mississippian shales. Tertiary volcanism and then Neogene crustal extension often masks or obliterates the pre-existing thrust belt. However, portions of relatively undisturbed thrust structures can be identified and mapped by a structural analysis utilizing balanced cross sections.

It is assumed that the CNTB has a classical Dahlstromian geometry. The front of the wedge thickening thrust belt is a blind thrust that detaches approximately the upper third of the sedimentary stack to form a belt of foothills folds. The sole of the belt is load deflected, and its gentle rearward (west) dip can be modeled with an assumed elastic rheology. The CNTB may have occurred, at least, in two phases, forming two distinct terrane types. One type is composed of very thick west-dipping thrust sheets that involve all the 7 to 12 km of Paleozoic rocks. The other type of terrane involves imbricate or duplex stacks of Devonian or Silurian carbonates over Mississippian shales that form smaller thrust sheets. They occur in clusters between the larger, older terrane, or fill duplex spac below the anticlinally warped crests of some of the major thrust fronts.

An iterative structural interpretation, adjusted with newly acquired seismic and well data, can help create a more accurate structural interpretation.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)