Internal Structure and Early Thermal Evolution of Mars from Mars Global Surveyor Topography and Gravity

TLDR

Mars Global Surveyor topography and gravity data reveal the planet’s global crust and upper mantle structure. Mars exhibits two crustal zones—a thinning crust from south to north over the southern highlands and Tharsis, and a uniform crust in the northern lowlands and Arabia Terra—whose lithospheric strength suggests early high heat flow in the north, elastic thickness increases with loading, and buried channels in the lowlands imply northward water and sediment transport before resurfacing.

Abstract

Topography and gravity measured by the Mars Global Surveyor have enabled determination of the global crust and upper mantle structure of Mars. The planet displays two distinct crustal zones that do not correlate globally with the geologic dichotomy: a region of crust that thins progressively from south to north and encompasses much of the southern highlands and Tharsis province and a region of approximately uniform crustal thickness that includes the northern lowlands and Arabia Terra. The strength of the lithosphere beneath the ancient southern highlands suggests that the northern hemisphere was a locus of high heat flow early in martian history. The thickness of the elastic lithosphere increases with time of loading in the northern plains and Tharsis. The northern lowlands contain structures interpreted as large buried channels that are consistent with northward transport of water and sediment to the lowlands before the end of northern hemisphere resurfacing.