基于分形理论的火星冲沟成因机制研究

A Study on Formation Mechanism of Gullies on Mars Based on the Fractal Theory

对火星陨击坑壁上发育的冲沟进行研究,分析其成因和控制因素并进而探讨火星表面附近发生的地质过程,是当今火星研究的重要课题之一。采用分形理论对火星南半球中纬度9个陨击坑壁内不同方位发育的冲沟沟头形态进行了研究,结果表明沟头的分维值与冲沟发育程度呈显著的正相关关系。冲沟沟头的分维值大小分布与冲沟的方位关系密切,面向极地的冲沟分维值较大,面向赤道的冲沟分维值较小。陨击坑内不同方位冲沟所处位置的局部气候因素差异控制了水量的大小,从而造成陨击坑内不同方位冲沟发育程度和分维值大小的差异。研究结果为强调火星气候因素控制了冲沟形成的地表冰雪积累/融化成因模式提供了佐证。

It is one of the most important challenges to research the controlling factors and formation mechanisms of Martian gullies at impact crater walls and sequentially to explore the geological processes near the surface of Mars. In this paper, the fractal theory was used to study the gully＇s alcoves in different orientations of nine craters at the mid-latitudes in the southern hemisphere of Mars. The results suggest significant positive correlation between the fractal characteristics of the gullies and the maturity of their development. The fractal values of the gully＇s alcoves have close relation to the orientations of gullies and the poleward facing gullies have higher fractal values than those of equatorward facing gullies. The local differences of climate characteristics in different orientations of the same crater walls mainly control the existence and amount of water, which causes the differences of the maturity and fractal values of gullies in different orientations of the crater walls. The results of our research provide one of the evidences for the accumulation/melting of surface snowpacks formation model.