Izu-Bonin-Mariana Arc - IBM Trench and Outer Trench Swell

IBM Trench and Outer Trench Swell

The oceanic trench and the associated outer trench swell mark where Pacific Plate begins its descent into the IBM Subduction Zone. The IBM trench is where the Pacific Plate lithosphere begins to sink. The IBM trench is devoid of any significant sediment fill; the ~400 m or so thickness of sediments is completely subducted with the downgoing plate. The IBM outer trench swell rises to about 300 m above the surrounding seafloor just before the trench. The lithosphere that is about to descend into a trench starts to bend just outboard of the trench; the seafloor is elevated into a broad swell that is a few hundred meters high and referred to as the "outer trench bulge" or “outer trench rise”. The about-to-be subducted plate is highly faulted, allowing seawater to penetrate into the plate interior, where hydration of mantle peridotite may generate serpentinite. Serpentinite thus generated may carry water deep into the mantle as a result of subduction.

Read more about this topic:  Izu-Bonin-Mariana Arc

Famous quotes containing the words trench, outer and/or swell:

    Language is the amber in which a thousand precious and subtle thoughts have been safely embedded and preserved. It has arrested ten thousand lightning flashes of genius, which, unless thus fixed and arrested, might have been as bright, but would have also been as quickly passing and perishing, as the lightning.
    —Richard Chenevix Trench (1807–1886)

    Self-alienation is the source of all degradation as well as, on the contrary, the basis of all true elevation. The first step will be a look inward, an isolating contemplation of our self. Whoever remains standing here proceeds only halfway. The second step must be an active look outward, an autonomous, determined observation of the outer world.
    Novalis [Friedrich Von Hardenberg] (1772–1801)

    Or don’t you like to write letters. I do because it’s such a swell way to keep from working and yet feel you’ve done something.
    Ernest Hemingway (1899–1961)