Crater floor fractures: Probes into habitable Martian environments Rebecca J.Thomas & Brian M. Hynek 1
1
1,2
LASP, University of Colorado, Boulder, CO 80309, USA, 2 Department of Geological Sciences, University of Colorado, 399 UCB, Boulder, CO 80309, USA.
[email protected]
1. Introduction: The astrobiological potential of floor-fractured craters The floor materials of over 400 Martian impact craters are cross-cut by large-scale fractures. In a sizeable subset of these, fracture formation is best explained by melting of near-surface ice and/or water upwelling, in response to magmatic intrusion [1,2,3].
We analyzed floor-fractured craters in Margaritifer Terra, a broad region to the east of Valles Marineris and south of Mars’ global crustal dichotomy (Fig 2). This area is ideal for studying the biopreservation potential of floor-fractured craters because it displays evidence for: 1. Extensive fluvial activity through the Uzboi-Ladon-Morava outflow channel system in the Late Noachian to Early Hesperian [4,5].
This makes floor-fractured impact craters important probes of potentially habitable Martian environments in two ways:
2. Mid-Hesperian chaos-formation and water outflow, including fracture-formation on the floors of numerous impact craters [4,5].
1. Where the fractures cut through Noachian (~4.1–3.7 Ga) crater lake sediments, they create deep cross-sections, potentially exposing biosignatures dating from a period when such surface environments were habitable. 2. Where aqueous fluids welled up through floor fractures in the Hesperian to Amazonian (
