CHASMA-BOREALE, MARS - A SAPPING AND OUTFLOW CHANNEL WITH A TECTONOTHERMAL ORIGIN

A detailed geomorphological study of Chasma Boreale, a widely known fe ature of Mars' north polar cap, has been carried out for the first tim e, 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 tectonic ally focused thermal event. Several lines of evidence indicate tectoni c control in the distribution and present aspect of most of the polar troughs. This tectonic forcing probably played a major role in the inc eption of not only Chasma Boreale but also other polar reentrants as w ell. (C) 1997 Academic Press.