Comparative Geoscientific and Geomatic Analysis of Hydrothermal Zones in Volcanic Terrain on Earth and Mars

Introduction: Evidence for past life on Mars is most likely to be found within the preserved mineralized remains of subaerial, subaqueous, and shallow subsurface hydrothermal systems [1,2]. The most important targets of endogenic-driven hydrothermal activity identified so far occur in structurally complex, highly dissected and/or faulted volcanic terrain [3]. Recent discoveries of sedimentary structures and other features diagnostic of shallow water deposits and saline groundwater at Meridiani Planum [4] also raise the possibility of hydrothermal venting in areas where evaporites were deposited in volcanic terrain. The study of these geologically complex areas on Mars will require the careful, concurrent analysis of multiple databases [5,6]. Layers of geological, topographic, structural, mineralogical, geophysical and geochemical data integrated in Geographic Information Systems (GIS) enable this type of detailed classification and interpretation of complex volcanic terrains on Earth. We present results based on the study of (1) hydrothermal chimneys and alteration zones of Cretaceous age located in the Canadian Arctic Islands, Nunavut, and (2) Apollinaris Patera shield volcano on Mars that were obtained using an OpenGIS solution for terrestrial analogues and planetary databases. Geology: On western Axel Heiberg Island, in the Canadian Arctic, erosional remnants of hydrothermal chimneys discovered at two localities consist of pyritiferous mounds that measure 2 to 5 m in cross-section and consist of a central vent and wide bands of whitish-yellow to ochre alteration (Fig. 1). The chimneys or alteration zones consistently occur in structurally complex areas where volcanic flows and/or sills intersect evaporite outliers at the periphery of the diapir. The salt domes were formed in an intracontinental rift basin when Upper Mississippian to Middle Pennsylvanian evaporite beds rose diapirically through the Mesozoic succession. Basaltic lava flows and pyroclastic deposits in this area were emplaced episodically, with peaks of intrusive and eruptive activity at 128 and 95 Ma, respectively [7]. Remarkably, cold springs are still active [8] and so there is growing evidence that hydrothermal systems constitute a longlived, episodic feature of the rift basin. The geological setting is broadly similar to that of conical siliceous mounds reported in the Parana basin of southeastern Brazil [9] with the following notable exceptions: statiform, intrusive mafic igneous rocks are pervasive in the Sverdrup Basin, and although the chimneys are of a similar size to some of the Parana structures, they are not as abundant.

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