Role of strike-slip faulting in the evolution of allochthonous terranes in the Philippines.

Concepts of allochthonous terrane transport and emplacement are dominated by the assumption that most terranes originate on the subducting plate, collide with the upper plate, and are emplaced there. Movement of terranes along the convergent margin is recognized but is generally attributed to postcollision slip. In the northern Philippines, allochthonous terranes originate primarily within the arc system, have been translated along it by strike- slip faults, and were 'emplaced' by cessation of that slip. We suggest that in the Philippines some originally vertical strike-slip boundaries may have evolved into shallow-dipping 'sutures' marked by fold and thrust systems. This mode of terrane evolution may be more common than generally appreciated, particularly in orogenic belts developed in response to oblique convergence. -Authors