The Antler Orogeny and the First Suspect Terrane: Middle Devonian to Late Pennsylvanian: Ca. 400–300 Ma

Abstract

From the Neoproterozoic through the Middle Devonian, a passive margin setting along Laurentia’s western edge resulted in great thicknesses of shallow marine carbonate rocks (limestone and dolomite), and lesser amounts of near-shore clastic rocks (sandstone and conglomerate). The extent of this passive margin sequence both temporally and spatially is impressive, lasting nearly 600 million years and trending from southeastern California to Alberta Canada. The passive margin conditions however, came to a crashing halt with the arrival of a series of exotic terranes at the Cordillera’s margin. With time, shallow marine carbonates were thrust faulted in allochthonous (Gr. “other Earth” – rock or block of rock transported from outside its present position) blocks over their stationary, autochthonous (rocks that lay where they were formed) cousins.