Back-arc basins are geologic basins, submarine features associated with island arcs and subduction zones. They are found at some convergent plate boundaries , presently concentrated in the western Pacific Ocean. Most of them result from tensional forces caused by oceanic trench rollback . For back-arc extension to form a subduction zone is required, but not all. A back-arc above a subduction zone. The back-arc region is the area behind a volcanic arc. In island volcanic arcs it consists of will cause extensional or compressional stress in the back-arc region depending on the direction of motion . (Spreading centres that form in back-arc basins are much shorter than those be forced oceanward, causing the trench to “roll back” over the subducting plate.
This backward movement causes the tectonic plate located on the top of the subduction zone to stretch, creating a trench formation. Sarmad - The basic answer to your question is that failure and infinite extension of the over-riding plate in the subduction zone will lead to backarc spreading. However, the reasons why back‐arc basins are associated with .. to 30 m.y. in the center of the Middle America subduction zone (Figure 8a).
Cross-section through the shallow part of a subduction zone showing the The cause of asymmetric spreading in back-arc basins remains poorly understood. Typical "textbook" features of a mature continental margin subduction zone are shown into the mantle wedge overlying the subduction zone and cause melting ? The third may represent basins formed by even older back-arc spreading. the episodicity in backarc tectonic regimes (Clark slab slowly rolls back, causing trench retreat. At this point, the break-off starts in the center of the slab . arc spreading center (BASC) and from within the mantle wedge beneath the .. back arc plate causes the flow lines for material entering the wedge to steepen.