SLAB WINDOW IN THE ACTIVE CONTINENTAL MARGIN

Progressive divergence of a subducting ridge will produce a slab window which forms and continues to expand between the subducted parts of the diverging oceanic plates. A slab window often forms at the subduction time of negative buoyant oceanic lithosphere of less than 10 Ma in age. The shape and size of a slab window are mainly controlled by the re-subduction ridge-transform-trench configuration, slab dip angles and vectors of plate convergence. The other factors to influence the shape and size of the slab window are still thermal erosion, phase change and others. The effects of slab windows on ancient convergent margin, the most active region in the Earth system, induce the multi-spheric interactions between asthenosphere, lithosphere, atmosphere and hydrosphere. Because the subduction of oceanic crust in the region is often intersected at a certain angle with the spreading axis, it is not only to induce asymmetric consumption of the oceanic basin, but also to produce the anomalous tectonics, magmatism, mineralization and thermal evolution of the overriding plate which are obviously different from those of the subduction of mid-ocean ridge parallel to subduction zone.