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Geomorphic Analyses of Debris Aprons Along the Martian Dichotomy Boundary, Tempe Terra/Mareotis Fossae Region, Mars
| Content Provider | Semantic Scholar |
|---|---|
| Author | Chuang, Frank C. Crown, David A. |
| Copyright Year | 2004 |
| Abstract | Numerical simulations have shown that depthdependent viscosity can increase the wavelength of mantle convection. The physical mechanism behind this observation and, by association, its robustness remain to be fully elucidated. Towards this end, we develop theoretical heat flow scalings for a convecting fluid layer with depth-dependent viscosity. Bottom and internally heated end-members are considered. For the former, the viscosity structure consists of a high viscosity central region bounded from above and below by horizontal low viscosity channels. For internally heated cases, only a surface low viscosity channel is present. The theoretical scalings show how depth-dependent rheology lowers the lateral dissipation associated with convective cells. This allows longer aspect ratio cells to form as the viscosity contrast between the channels and the central region is increased. The maximum cell extent is determined by the condition that the pressure gradients that drive lateral flow in the channels do not become so large as to inhibit vertical flow into the channels. Scaling predictions compare favorably to results of numerical simulations at low to moderate Rayleigh numbers. As the Rayleigh number driving convection is increased, time-dependence sets in in the form of small scale boundary layer instabilities. This increases lateral dissipation within the channels and the maximum cell extent decreases as a result. Internally heated simulations show that a near surface high viscosity layer, a lithosphere analog, can suppress these small scale instabilities. This allows a low viscosity channel to maintain large aspect ratio cells at high |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://www.lpi.usra.edu/meetings/hemispheres2004/pdf/download/alpha_a-l.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
