Insights Into Subduction Zone Dynamics

Abstract

The dynamics of Earth's subduction zones can be examined through a combination of geophysical, geological, and geochemical observations of modern margins, theoretical study, and research on metamorphic rocks representing ancient subduction. No two modern subduction zones are alike—each has its own character and behavior. Recent work on subduction zone dynamics has increasingly examined individual margins rather than making broad generalizations regarding categories of subduction zone properties and processes. Many factors can distinguish one margin from another, to name a few, convergence rate, age and thermal structure of the incoming plate, subduction obliquity, makeup of the upper plate, thicknesses and types of subducting sediment, whether sediments are being accreted or the forearc is being eroded, and the subduction of features such as oceanic plateaus, abandoned or active spreading ridges, and fracture zones. In fact, the hugely varied combinations of these factors lead to the generation and evolution of subduction margins with incredibly diverse behavior and associated hazards to society in the form of earthquakes, tsunamis, and volcanic eruptions. In some cases, variations in behavior of an individual margin, along its strike, can clarify the most important forcing factors in its evolution. The greatest advances in subduction zone science will be provided by multidisciplinary groups assembled to consider the full complexity of margins both modern and ancient.