Periodic climate change on Mars: Review of evidence and effects on distribution of volatiles

Abstract

The polar regions of Mars preserve, in both their layering and their topography, a record of recent climate changes. Because of the coincidence of the growth of the northern seasonal cap with global dust storms, dust may be currently accumulating on the northern cap, but conditions at the poles will alternate with the precessional cycle. Deposition is also modulated by changes in eccentricity and obliquity, which interact complexly, affecting initiation of global dust storms, the stability of volatiles at the surface, and global wind regimes. Formation of spiral valleys and low undulations on the surface of the layered deposits may result from preferential sublimation of volatiles on sunward-facing slopes and condensation on the adjacent flats, with the rates also modulated by astronomically caused insolation variations. Lack of impact craters on the surface and lack of interruption of the layers by impact scars suggest that the polar deposits are no more than a few million years old. Older deposits may have been periodically removed, as indicated by etch-pitted terrain at the south pole and by superposition relations around the periphery of the present layered deposits. Evidence of ancient periodic climate changes that occurred before formation of the present layered terrain is fragmentary but includes pedestal craters, parallel moraine-like ridges, and etched ground at high latitudes. Perturbation of the orbital motions also results in adsorption and desorption of volatiles in the regolith, which leads to variations in atmospheric pressure and partial dehydration of the equatorial near-surface materials.

Thermophysical properties of Alaskan loess: An analog material for the Martian polar layered terrain?

“…The PLT also contains regions of erosion scarps with slopes of 20-25 ø (Herkenhoff and Murray, 1990). The thickness of the layers, the amount of volatiles contained in them and scarp slopes are believed to vary with wind regimes, soil properties, and global climate changes (Carr, 1982) years. The boundary between the weak desiccated layer and underlying ice-dhch frozen soil is distinct and hard.…”

Surface properties of Mars' polar layered deposits and polar landing sites

“…The model of Squyres [ 1979] incorporates elements of all three scenarios. The various ideas are reviewed in more detail by Carr [1982] and Thomas et al [1992].…”

Topography and Geologic Characteristics of Aeolian Grooves in the South Polar Layered Deposits of Mars

“…As such, they preserve what is probably the best source of information about the recent climate history of Mars (Murray et al 1972, Cutts et al 1976, Cutts et al 1979, Squyres 1979, Toon et al 1980, Carr 1982, Howard et al 1982, Plaut et al 1988, Clifford et al 2000. Stratigraphic interpretation of the layers in terms of global climate change is complicated by the significant difference in surface ages between the north and south PLD inferred from crater statistics (Cutts et al 1976, Plaut et al 1988 Herkenhoff and Plaut 2000).…”