The geologic map shows lava flows and fan-shaped deposits on Pavonis Mons, the central of three large shield volcanoes (Arsia, Pavonis, and Ascraeus Montes) that form the Tharsis Montes volcanic chain. The volcanoes lie along the crest of a regional northeast-trending rise that extends more than 3,000 km across the western equatorial region of Mars (fig. 1). The volcanic history of Pavonis Mons is similar to that of other volcanoes in the western equatorial region of Mars (Scott and others, 1981a-c; Scott and Tanaka, 1981, 1986; Zimbelman and Edgett, 1992). Previous geologic mapping of this region (Scott and others, 1981a-c; Scott and Tanaka, 1981, 1986) shows six major lava flows that were extruded from the Tharsis volcanoes during the Early Hesperian to Late Amazonian Epochs; four of these lava flow members are present in the map area. On the northwest flank of Pavonis Mons, broad, lobate, fan-shaped deposits form a surficial cover similar to other fan-shaped deposits on the northwest flanks of Arsia, Arcaeus, and (to a lesser degree) Olympus Mons. Similar to those of Arsia Mons, the fan-shaped deposits of Pavonis Mons consists of several facies whose origins are attributed to glaciation, mass wasting, and pyroclastic volcanism origins.
