Detachment levels in the Marathon fold and thrust belt, west Texas

► We present a model for the structural architecture for the Marathon fold and thrust belt. ► New subsurface data is incorporated with surface exposures. ► A bed-parallel detachment in the lower Tesnus Formation separates structural lithic units. ► A perched décollement in the foreland was later reactivated as a roof thrust to duplex systems. ► The structural model we present may be applicable to much of the Ouachita orogenic system.