A geomorphic analysis of Hale crater, Mars: The effects of impact into ice-rich crust

Widespread crater-related pitted materials on Mars: Further evidence for the role of target volatiles during the impact process

“…1) associated with both interior and exterior deposits of pristine and well-preserved impact craters. Pitted materials often occur with other notable features, such as various types of flows, channels, dissected deposits and alluvial fan-like features, all of which have been described in previous studies (e.g., Morris et al, 2010;Williams and Malin, 2008;Jones et al, 2011). Although previously recognized in some craters (McEwen et al, 2005;Tornabene et al, 2006;Mouginis-Mark and Garbiel, 2007;Preblich et al, 2007;Hartmann et al, 2010;Morris et al, 2010), these crater-related pitted materials have not been characterized on a global scale and over a range of crater diameters.…”

“…13 and 14), while the relatively steeper areas between the ponds ($5-10°) correspond to the flows in the image. 2010; Jones et al, 2011), but also the dissected appearance of crater ejecta when it is closely associated with ejecta pitted materials (e.g., Fig. 13).…”

The origin and timing of fluvial activity at Eberswalde crater, Mars

“…Mechanisms that could connect impacts to fluvial activity include: (1) long-term hydrothermalism in large craters that struck an ice-rich target (Brakenridge et al, 1985;Newsom et al, 1996;Abramov and Kring, 2005), (2) release of water from subsurface ice excavated by the crater as observed around Hale crater (Jones et al, 2011), (3), short-term hydrothermal due to warm ejecta blanketing shallow ice, as observed for Sinton crater which displays braided fluvial valleys on its ejecta , and observed in less spectacular fashion for >40 craters of 10-100 km in diameter located in the mid-latitudes (Mangold, 2012), (4) episodic snow deposition from climatic processes could melt if it lands on warm crater rims and ejecta, possibly explaining observations at Mojave crater -Mojave displays unexplained but presumably impact-associated activity with well-developed gullies and depositional fans on its inner slope (Williams and Malin, 2008), or (5) an impact into an ice-bearing crust that generates temporary climate modifications leading to precipitation if the impactor is big enough (Segura et al, 2002(Segura et al, , 2008Toon et al, 2010). All these processes require the existence of ice in the subsurface, or near the surface as snow/ground ice.…”

Mars: a small terrestrial planet

“…They are also more patchy and located around specific features, such as volcanoes (Alba Patera, Ceraunius Tholus) or impact craters (e.g., Cerulli, Lyot, Hale craters) suggesting relationships with these heat sources (Fig. 27c, d) (Gulick and Baker 1990;Dickson et al 2009;Jones et al 2011). In addition, many of these relatively young features are found in the midlatitude bands, typically 30 • -50 • of latitude in both hemispheres, where massive ice deposits have been interpreted to have formed (e.g., Kreslavsky and Head 2002;, suggesting that these valleys developed through local/transient melting of ice (Fassett et al 2010;Mangold 2012;Mangold et al 2012b).…”

“…While these valleys are clearly influenced by the presence of ground or surface-ice, the mechanism of melting is debated. Examples on the ejecta of craters point toward heating by impact warming (Jones et al 2011), but episodic climate change has been invoked as well (Hobley et al 2014). These observations may be connected to small valleys observed on volcanoes and may be related to volcanic/geothermal heating, especially on Alba Patera (Gulick and Baker 1990) which have Early Amazonian age and were a unique example of Amazonian valleys at the time of their discovery.…”