International Ocean Discovery Program (IODP) Expedition 352 recovered a high-fidelity record of volcanism related to subduction initiation in the Bonin fore-arc. Two sites (U1440 and U1441) located in deep water nearer to the trench recovered basalts and related rocks; two sites (U1439 and U1442) located in shallower water further from the trench recovered boninites and related rocks. Drilling in both areas ended in dolerites inferred to be sheeted intrusive rocks. The basalts apparently erupted immediately after subduction initiation and have compositions similar to those of the most depleted basalts generated by rapid sea-floor spreading at mid-ocean ridges, with little or no slab input. Subsequent melting to generate boninites involved more depleted mantle and hotter and deeper subducted components as subduction progressed and volcanism migrated away from the trench. This volcanic sequence is akin to that recorded by many ophiolites, supporting a direct link between subduction initiation, fore-arc spreading, and ophiolite genesis

Migmatite domes are common in metamorphic core complexes. Dome migmatites deform in the partially molten or magmatic state and commonly record complex form surfaces, folds, and fabrics while units mantling the dome display a simpler geometry, typically formed by transposition during crustal extension. We use field observations and magnetic fabrics in the Naxos dome (Greece) to quantify the complex flow of anatectic crust beneath an extensional detachment system. The internal structure of the Naxos dome is characterized by second‐order domes (subdomes), pinched synforms, and curved lineation trajectories, which suggest that buoyancy‐driven flow participated in dome evolution. Subdomes broadly occur within two compartments that are separated by a steep, N‐S oriented, high‐strain zone. This pattern has been recognized in domes formed by polydiapirism and in models of isostasy‐dominated flow. The preferred model involves a combination of buoyancy‐ and isostasy‐driven processes: the Naxos dome may have been generated by regional N‐S extension that triggered convergent flow of partially molten crust at depth and the upwelling of anatectic migmatites within the dome. This pattern is complicated by gravitational instabilities and/or overturning of the high melt fraction crust leading to the growth of subdomes. As the migmatites within the Naxos dome reached a higher structural level, they were affected by regional top‐to‐the‐NNE kinematics of the detachment system. Dome formation therefore occurred by a combination of coeval and coupled processes: upper crustal extension, deep crust contraction during convergent flow of anatectic crust, diapirism and/or density‐driven crustal convection forming subdomes, and north directed detachment kinematics.

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Multi‐domain magnetites display a normal anisotropy of magnetic susceptibility (AMS) fabric where grain shape axes coincide with AMS axes. By contrast, single‐domain magnetite has an inverse magnetic fabric where magnetic axes are interchanged. The mixing of normal and inverse magnetic fabrics results in intermediate fabrics. Theoretical models for intermediate fabrics consider all combinations of normal and inverse fabrics. The minimum amount of inverse component required for intermediate fabrics to form is about 20% in the case of prolate normal (T = −0.50) and prolate inverse (T = −0.42) components. Such a small amount of inverse component may not be noticed. The anisotropy resulting from intermediate fabrics is lower than that of the normal or inverse contribution to AMS. This suggests that whenever intermediate fabrics occur neither the shape factor nor the degree of anisotropy relate to strain in a simple way.