A detailed structural analysis across a regional unconformity, forks of the Canning River, Franklin Mountains, northeastern Brooks Range, Alaska.

摘要

Structural analysis on the northern flank of the 'Franklin Mountains anticlinorium,' northeastern Brooks Range, Alaska, addressed the geometry and sequence of structures, and the deformational mechanics of the Franklinian and Ellesmerian sequences, which are separated by a sub-Mississippian unconformity. The anticlinorium is comprised of two horses of Franklinian sequence rocks in a Cenozoic north-vergent duplex thrust system. South-dipping pre-Mississippian slaty cleavage may have been a plane of preferred failure during ramp formation. Above the unconformity, the Kekiktuk Conglomerate remained attached to pre-Mississippian rocks, deforming with them beneath a roof thrust in the Mississippian Kayak Shale. Increased shear stress and overburden pressure beneath overthrust Franklinian sequence rocks may have led to local detachment near the unconformity surface. Above the Kayak Shale, progressive detachment folding and thrust faulting occurred in the Lisburne and Sadlerochit Groups as a result of emplacement of the two underlying horses.