This paper separates the small oceanic basins around the western perimeter of the Pacific Ocean into marginal basins that have formed through back-arc extension and those that apparently have not, and reviews our knowledge of magnetic lineation patterns observed in possible and probable back-arc basins. Magnetic lineations in these basins resemble lineations commonly associated with the world’s mid-oceanic spreading systems, indicating that similar processes of crustal accretion occur in both tectonic environments. In some back-arc basins of the southwestern Pacific, magnetic lineation and other evidence suggest that back-arc basins can evolve through the interaction and growth of ‘multi-plate’ systems. Because of the small time and space characteristics of back-arc basins compared with the world’s major oceanic spreading systems, tectonic conditions favourable for the generation of back-arc basins are either relaxed rapidly or easily interrupted. Models proposed to account for back-arc basin development include (a) ‘local’ models, where back-arc extension is mechanically driven by the downgoing slab, and (b) global plate kinematics models, where conditions favourable for back-arc extension are governed by the motion of the overriding plate relative to the trench axis.
Geochronology and geochemistry of the Early Jurassic Yeba Formation volcanic rocks in southern Tibet: Initiation of back-arc rifting and crustal accretion in the southern Lhasa Terrane
