Chasma Boreale, Mars: A sapping and outflow channel with a tectono-thermal origin

A detailed geomorphological study of Chasma Boreale, a widely known feature of Mars' north polar cap, has been carried out for the first time, along with a quantitative paleohydrological model. It is concluded that the chasma was eroded by a flow whose discharge was on the order of magnitude of 10(9) m sec(-1). This catastrophic flow is thought to have been preceded by a powerful sapping process, caused by a tectonically focused thermal event. Several lines of evidence indicate tectonic control in the distribution and present aspect of most of the polar troughs. This tectonic forcing probably played a major role in the inception of not only Chasma Boreale but also other polar reentrants as well. (C) 1997 Academic Press.