An ancient cold, glacier-rimmed ocean could explain the unusual mineral make-up of the martian northern lowlands, suggests a paper published online in Nature Geoscience.

Alberto Fairen and colleagues used climatic and geochemical modelling to assess why the early crust of the northern lowlands lacks a mineral group called phyllosilicates, relative to similarly aged crust in the southern highlands. Their calculations showed that if ― as previously proposed ― an ocean existed in the northern lowlands, it would have been close to freezing. Furthermore, features around the proposed ocean basin are consistent with the presence of large glaciers. Near-freezing temperatures and large glaciers would prevent the formation and deposition of phyllosilicate minerals in the lowland ocean basin.

The authors note that the distinct mineralogical difference between the northern lowlands and the southern highlands that would arise from such a system is consistent with the martian mineralogy that has been derived from satellite observations.