THRUST, RELATION WITH DEEP-SEATED SHEAR ZONE

The thrusts are formed as a result of maximum principal compressive stress remaining tangential to the earth's surface and the thrust faults are usually gently dipping. To allow for the stress configuration at all levels to be maintained, these can therefore be traced into steeply dipping ductile shear zones in the basement. The acute angle between the complementary thrusts faces sigma1, parallel to the obtuse angle bisectrix for the related shear zones in the basement.