Volcanic geology of Hadriaca Patera and the eastern Hellas region of Mars

A detailed examination of the geomorphology of Hadriaca Patera, a low-relief volcano in the southern highlands of Mars northeast of the Hellas basin, is presented, and the surrounding eastern Hellas region is considered in order to assess whether the volcanic geology of Hadriaca Patera is consistent with previous characterizations and highland paterae. The morphologic characteristics of the channels suggest erosion by groundwater sapping and surface runoff. The erosional morphology of the volcano, the lack of lava flow features, and the friable nature of the flank materials indicate that Hadriaca Patera consists predominantly of pyroclastic deposits. From the predominance of hydrovolcanic eruptions in the development of Hadriaca and Tyrrhena patera, it is inferred that the transition in volcanic eruption style can be attributed to a volatile depletion of the crust, whereas magmatic eruptions at the paterae would be indicative of temporal changes in Martian magmas.