Perron J Taylor, Mitrovica Jerry X, Manga Michael, Matsuyama Isamu, Richards Mark A
Department of Earth & Planetary Science, University of California, Berkeley, California 94720, USA.
Nature. 2007 Jun 14;447(7146):840-3. doi: 10.1038/nature05873.
A suite of observations suggests that the northern plains of Mars, which cover nearly one third of the planet's surface, may once have contained an ocean. Perhaps the most provocative evidence for an ancient ocean is a set of surface features that ring the plains for thousands of kilometres and that have been interpreted as a series of palaeoshorelines of different age. It has been shown, however, that topographic profiles along the putative shorelines contain long-wavelength trends with amplitudes of up to several kilometres, and these trends have been taken as an argument against the martian shoreline (and ocean) hypothesis. Here we show that the long-wavelength topography of the shorelines is consistent with deformation caused by true polar wander--a change in the orientation of a planet with respect to its rotation pole--and that the inferred pole path has the geometry expected for a true polar wander event that postdates the formation of the massive Tharsis volcanic rise.
一系列观测结果表明，火星的北部平原覆盖了近三分之一的火星表面，这里可能曾经存在过一片海洋。也许支持古代海洋存在的最具启发性的证据是一组环绕平原数千公里的地表特征，这些特征被解释为不同年代的一系列古海岸线。然而，研究表明，沿着假定海岸线的地形剖面包含幅度高达数公里的长波长趋势，这些趋势被用作反对火星海岸线（以及海洋）假说的论据。在这里，我们表明，海岸线的长波长地形与真极移（即行星相对于其自转轴的方向变化）引起的变形一致，并且推断出的极移路径具有与巨大的塔尔西斯火山隆起形成之后发生的真极移事件预期相符的几何形状。
