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Aeolian process is the most active and extensive contemporary geomorphological process on the Mars, bearing rich information on surface processes, environment and evolution history. High-resolution remote sensing images covering the whole planet are interpreted and processed by GIS software to analyze the morphological characteristics of the Martian dunes on global basis, and discuss their aeolian geomorphological implications. A tentative dune classification scheme is proposed for the Mars. Dunes types on the Mars mainly include sand sheet, dome dune, barchan, barchanoid ridge, transverse ridge, linear ridges, seif dune, raked linear dune, nail dune, square dune network, ladder-like dune network, scaled dune network, honeycomb dune network, star dune, and obstacle dune. It is suggested that the Mars shares similar dune types with the Earth to a large extent, but is dominated by simple dune types. Complex and compound dunes are rarely seen on the Mars so that the cumulative probability curves of dune morphological parameters are characterized by a single section. Barchans, barchanoid ridges and transverse ridges are the most popular, but linear dunes that account for about 50% on the Earth only have 10% on the Mars. The simplicity of dune geomorphology on the Mars is also manifested by the small patches of the dune fields the Martian dune-fields. The Martian dunes are generally smaller on the Mars, in contradiction with theoretical inferences that the scale of dunes increases the ratio of particle/air density. The morphological parameters of the Martian dunes are well correlated, similar to the Earth dunes, but the correlationship is different, implying the similar formation mechanism but different development conditions. It is also suggested that the Martian analogues of terrestrial aeolian landforms, such as those found on the Tibetan Plateau, are good examples to study the Martian aeolian geomorphology. The simplicity of dune geomorphology on the Mars probably suggests that dunes on the Mars are developed with insufficient sediment availability and short development history. Inactive recent exogenic processes are probably responsible for insufficient sediment availability on the Mars. Insufficient sediment availability would be an interesting topic for future research, which may have extensive earth science significances. |
