VOLCANOTECTONIC PROCESSES NEAR MARS’ DICHOTOMY BOUNDARY (Invited Presentation)
We show widespread evidence for flat-topped deposits with steep, lobate margins intimately associated with Hesperian to Amazonian extensional fractures across the Margaritifer Terra region, particularly within the Ladon basin and floor-fractured impact craters. The morphology and inferred mineralogy of these deposits is most consistent with lava flow sourced from the fractures. A volcanic interpretation is supported by the discovery of several constructive edifices around the margin of the Ladon basin associated with diffuse-margined material with a similar spectral signature, which we interpret as pyroclastic. The lava deposits overlie Noachian sediments scoured by fluid outflow from the fractures and are themselves eroded by such fluids, indicating a complex history of fracture-sourced volcanic and aqueous activity. Thus, we show that volcanic activity at Mars’ dichotomy boundary was indeed closely associated with extensional tectonics and fluid outflow, supporting a genetic relationship between these three processes.
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