火星沙丘地貌的形态学窥究

A morphological insight into the Martian dune geomorphology

风沙地貌过程是最活跃最普遍的现代火星地貌过程,蕴含火星地表过程、环境和演化历史的丰富信息.本研究利用覆盖火星全球高分辨率的遥感影像,在地理信息系统软件的支持下,在全球尺度上分析火星沙丘地貌的形态学特征,挖掘所蕴含的风沙地貌学意义.结果表明,火星沙丘地貌类型与地球沙丘地貌相似,但仅以简单沙丘为主,罕见复合和复杂沙丘,沙丘形态参数累计概率曲线表现为简单一段式.火星沙丘以新月形沙丘、新月形沙丘链和横向沙丘等初级类型为主,而占地球沙丘约50%的线形沙丘在火星上占不到10%.火星沙丘规模较地球沙丘小,与理论上应具有更大规模的沙丘相悖.火星沙丘地貌形态参数间与地球沙丘呈现相似的良好相关性,但相关关系不同,意味着具有相似的形成机理,但不同的形成条件.得到的另一重要启示是,在地球上研究类火星风沙地貌,如青藏高原的类火星风沙地貌,是认识火星风沙地貌及其发育环境的有效途径.

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 about50%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.