Metal Deposits on the Inner Sides of Principal Arcs

Abstract

In mature island arc systems (e.g., Japan) and Cordilleran belts, a spectrum of metal deposits form that are sufficiently distinctive from those of principal arcs to merit separate consideration. They tend to exhibit a close spatial association with isolated stocks that intrude the zone on the inner side of principal arcs. The precise demarcation of this zone is not easy and is particularly tenuous in situations where the principal arc itself has migrated back and forth relative to the trench axis. As suggested in the previous chapter, backarc magmatism and related metallogenesis is probably a function of subduction attaining some critical low angle (Fig. 2.1), and thus backarc metal deposits differ in degree rather than kind from principal arc deposits.