Dynamic Disappointment

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Science  18 Oct 2002:
Vol. 298, Issue 5593, pp. 497-499
DOI: 10.1126/science.298.5593.497f

Near-surface horizontal tectonics have shaped much of Earth's topography; many sedimentary basins, for instance, apparently stemmed from horizontal stretching of the lithosphere, followed by cooling, subsidence, and sedimentary infilling. However, some theoretical models have concluded that a substantial part of Earth's surface topography might be tied to density-driven flow in the mantle. For example, the subduction of cool, dense slabs in the mantle, viscously coupled to the overlying lithosphere, could “pull down” Earth's surface—by as much as 1 to 2 km. The possibility of such dynamic topography has profound implications for how we understand basin formation, but determining subsidence contribution in real sedimentary basins has been difficult.

Wheeler and White analyzed age, depth, and sedimentary thickness data from wells, seismic reflection profiles, and other sources over a wide area of Southeast Asia, where models have predicted some of the largest amplitudes of dynamic topography on Earth. The maximum basin depth that could potentially be explained by dynamic topography amounts to around 300 m, far less than the 1 to 2 km predicted by numerical models. — SW

Tectonics 10.1029/2001TC900023 (2002).

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