Head has also written on this with his student David Shean:

PAVONIS MONS FAN-SHAPED DEPOSITS — SMOOTH TERRAIN SURFACE ICE DEPOSITS. D. E.
Shean1 and J. W. Head1, 1Brown University, David_Shean@Brown.edu, James_Head@Brown.edu
Lunar and Planetary Science XXXIV (2003) 1154.pdf
"Elsewhere, we have presented evidence supporting a cold-based glacial origin for the Pavonis deposits [3]. Here, we present evidence suggesting that the smooth facies represents residual ice deposits that have persisted until the present."
...
"We interpret the smooth terrain to be dust-covered residual ice from the last major Pavonis Mons ice sheet. Under current martian climatic conditions, water
ice may theoretically be stable at the surface within the Tharsis rise due to the low thermal inertia of the soil and the lower mean annual temperature of the region [9]. The proposed ice sheet could have formed during periods of high obliquity [10] where equatorial
regions receive less solar insulation than the poles and can become cold traps [11]. Excess water in the atmosphere
would be deposited at low latitudes, resulting in significant equatorial ice accumulations. The stability of water ice at the surface is only increased with greater burial depth, and the smooth terrain is covered by dunes that appear to be tens of meters high. The smooth facies is of the order of hundreds of meters thick at present and this suggests that a significant ice component remains in the near surface today. Thus, the Pavonis Mons fan-shaped deposits could be a site where hundreds of millions of years-old glacial ice could be sampled during future exploration."
http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1154.pdf

Bob Clark