Trends in effusive style at the Tharsis Montes, Mars, and implications for the development of the Tharsis province



[1] We mapped lava flows on the Tharsis Montes (Arsia Mons, Pavonis Mons, and Ascraeus Mons) using High Resolution Stereo Camera images that centrally transect each shield from north to south, covering ∼20% of each shield's surface. These data were co-registered to Mars Orbiter Laser Altimeter, Thermal Emission Imaging System, and Mars Orbiter Camera data, enabling lava flow structures and vents to be consistently differentiated across each volcano. Lava flow and vent abundances and relationships are used to provide new insight into the late Amazonian eruptive history of the Tharsis Montes. The volcanoes are divided into their main flanks, rift aprons, and small-vent fields. Where present on the main flanks, channel-fed flows always embay tube-fed flows, indicating a change from long-lived, stable tube-forming eruption conditions to shorter-lived, less stable channel-forming eruption conditions. Superposition relationships suggest that main flank and rift apron development were likely separated by an eruptive hiatus. The rift aprons, as compared to the main flanks, show higher abundances of tube- and channel-fed flows, and embayment of tube-fed flows by channel-fed flows is less consistent. Several trends from the Arsia Mons, to Ascraeus Mons, southwest rift aprons and small-vent fields were identified, including increased tube abundance, median slope, and number of satellitic eruptive vents and a decrease in channel- to tube-fed flow ratios, apron volumes, and maximum apron elevations. These trends suggest that the most recent volcanic activity at the Tharsis Montes might have originated from a single, shared magma source, possibly marking a change in magma production style from main flank construction.