Qaidam Basin as an analog for linear dune formation in Chasma Boreale, Mars: A comparative analysis

摘要

This paper identifies a terrestrial analog for linear dune fields in the Chasma Boreale, located in the north polar region of Mars, and analyzes it to explain linear dune formation. The straight indurated linear dunes are elongated downwind of dome dunes and barchans under a unimodal wind regime, providing a novel research opportunity for geomorphologists to investigate the coexistence of transverse and longitudinal dunes and the effect of sediment induration on dune morphology. The linear dunes around the Chaerhan salt lake in the Qaidam Basin are good analogs for the Chasma Boreale linear dunes because of the similarities in dune morphology and evolution process. Further, the effects of the indurating agents (salt and ice) on the formation of the linear dunes are similar in both locations. In this paper, we have contrasted and analyzed their dune patterns, the influence of cohesive sediment, and wind regimes in the two areas. The formation process and underlying mechanisms that create the linear dunes are analyzed through geomorphological evidence and dune flow simulation experiments. The results show that there is a remarkable morphological resemblance between the two areas. Cohesive sediments, especially the interbedded frozen laminae on Mars, increase dune stability, and thus allow the formation of linear dunes under a small divergence-angle in a bidirectional wind regime. The proto-linear dune facilitates the deposition of sediment along the major axis of the dune, and the lateral wind maintains and promotes the development of linear dunes. We also discuss how cohesive sediment influences dune morphology and leads to a transition from barchans to linear dunes, and we examine the feedback between dune form and airflow. The different effects of sediment induration on dune morphology make the determination of aeolian patterns less certain, which has implications for the development of climate models of Mars and Titan. (C) 2018 Published by Elsevier B.V.