The draa Cerro Medanoso (Atacama, Chile) and its importance in the study of desert

Abstract

This work presents a morphological analysis of the Cerro Medanoso draa (Atacama Marginal Desert) and the type of contact with the desert pavements of neighboring glacis and piedmont. This study is based on an analysis of aerial photos, and a digital elevation model. Aster GDEM was used as a basis for the survey. Fieldwork observations covered two principal zones: the nucleus and the envelope. Following fieldwork, analysis of satellite imagery was conducted. It was possible to identify the following phases of formation: construction of a stellate nucleus, merging of the eastern envelope, merging of the southern envelope and merging of a complex western envelope. The southeastern facing envelope is much bigger than the northwestern facing one. Consequently, the construction of the complex draa is asymmetric. The correlation of this megadune with similar star and compound draas to other deserts in the world indicates that the closest analogue exists in Namibia, but without merging signals between the envelope and the nucleus. Star draas observed in other deserts exhibit a lack of this envelope. With reference to the neighboring piedmont, the beginning of its deflation must be necessarily correlative to the initial construction of the nuclear twin star draa. The later deflation could be responsible for the pulses, which formed the envelope. Therefore, the neighboring desert pavement and the draa are correlative landforms, which represent a very long time formation, in an important part of the desert history, as evidenced by the cited and referenced research works.