Early Cenozoic global plate reorganization

Abstract

Synthesis of regional plate movements reveals a major reorganization of global plate motion from Mesozoic to Cenozoic patterns that occurred primarily during the Eocene epoch (53.5 to 37.5 m.y. B.P.). The reorganization involved reorientation of relative plate motions with large N-S components into large E-W components, continuation of pre-existing E-W sea floor spreading, initiation of new E-W spreading, deceleration of spreading rates, and obduction of ophiolites. The reorganization is attributed to increase in resistance imposed on the global plate system by increase in length of E-W-trending collisional plate boundaries from 2500 to 28,500 km during the interval 55 to 40 m.y. B.P., forcing the system to reorient along lines of less resistance. The pattern of global plate motion resulting from the reorganization is constrained by the resistance imposed by 19,000 km of collisional plate boundaries.