| Summary: | Convergent plate margins serve as the principal locations of lithospheric assembly and destruction within the Earth system. Subduction zones transfer material between the surface and interior of the Earth as they build continents through arc magmatism and recycle oceanic lithosphere back into the mantle. Continental collisions terminate subduction, develop topography, and bring rocks from depth to the surface of the Earth. However, the transition within a convergent margin from subduction to terminal collision is complicated by transient intermediate processes, including marginal basin formation and terrane accretion. This dissertation represents a multi-disciplinary geochemical, geochronologic, and geodynamic exploration of marginal basins and terrane accretion within convergent margins, informed by the spatiotemporal framework that field-based structural geology provides. The problems investigated here are focused on and/or inspired by the Greater Caucasus Mountains, at the northernmost edge of the active Arabia-Eurasia continental collision. The Greater Caucasus represents a long-lived convergent margin spanning the entire Phanerozoic, with the structure of the present-day collisional orogen strongly controlled by prior convergent margin processes, most notably the Jurassic formation and Cenozoic closure of the Caucasus Basin, a marine back-arc basin associated with the Lesser Caucasus volcanic arc.The Caucasus Basin is an example of a back-arc basin that initiates within continental rather than oceanic lithosphere, and the geochemical characteristics of magmatic rocks within continental back-arcs are poorly understood relative to their intraoceanic counterparts. In Chapter 1, I compile published geochemical data from five exemplar modern continental back-arc basins – the Okinawa Trough, Bransfield Strait, Tyrrhenian Sea, Patagonia plateau, and Aegean Sea/Western Anatolia – to establish a geochemical framework for continental back-arc magmatism. This analysis shows that continental back-arcs yield geochemical ...
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