TESTING GLOBAL SYNCHRONISM IN PERI-PACIFIC ARC VOLCANISM

Episodicity of arc volcanism along the Pacific rim is quantitatively analysed based on the record preserved by ash layers in deep-sea sediments (drilled by the Deep-Sea Drilling Project and the Ocean Drilling Program). Two major pulses of arc volcanism have been found, one during Middle Miocene times (18-13 Ma), the other during Pliocene-Quaternary times (5-0 Ma). These pulses are shown to relate to the tectonic (stress) regime of the arc lithosphere rather than to subduction rate. These episodes of arc volcanism activity coincide with major tectonic events documented on circum-Pacific subduction zones. As a consequence, a global control of plate kinematics could influence both volcanic and tectonic evolution of Pacific convergent margins.