Time will tell: temporal evolution of Martian gullies and palaeoclimatic implications

Abstract

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Initiation and Flow Conditions of Contemporary Flows in Martian Gullies

“…The crater contains a central peak and multiple wall terraces (e.g., Melosh, 1989), and is estimated to have formed around 1 Ga (Jones et al, 2011). Gullies are abundant on both the central peak and crater walls on multiple slope orientations (e.g., Dickson et al, 2007;De Haas et al, 2017;Kolb et al, 2010;Reiss et al, 2009;Reiss et al, 2011). Numerous new flow deposits have formed in Hale crater gullies over the last decade (Dundas et al, 2012;Dundas et al, 2015;Dundas et al, 2017;Kolb et al, 2010;McEwen et al, 2007).…”

“…Gullies are kilometer-scale alcove-channel-fan systems that are present on steep slopes in midlatitude to polar regions on Mars (e.g., Conway et al, 2017;Harrison et al, 2015;Malin & Edgett, 2000). They are geologically very young features that have been active over the last few million years (De Haas et al, 2015a;De Haas et al, 2017;Johnsson et al, 2014;Reiss et al, 2004;Schon et al, 2009). Their formation has been linked to both a range of dry (e.g., Cedillo-Flores et al, 2011;Dundas et al, 2010;Dundas et al, 2012;Dundas et al, 2015;Dundas et al, 2017;Pelletier et al, 2008;Treiman, 2003) and wet flows (e.g., Costard et al, 2002;Conway et al, 2011;Conway et al, 2015;De Haas et al, 2015b;De Haas et al, 2015c;Gulick et al, 2019;Hartmann et al, 2003;Johnsson et al, 2014;Levy et al, 2010;Lanza et al, 2010).…”

“…Mixing within the falling material will allow the generated heat to be transferred to the CO 2 frost, causing sublimation, enhancing the gas pressure within the pores of the flowing mass leading to fluidization of the flow. Complete fluidization is not necessary to explain all recent Martian gully flows, as the gully fans are moderately steep, roughly ranging between 10 • and 15 • (Conway & Balme, 2016;Gulick et al, 2019), and sometimes consistent with no fluidization (Kolb et al, 2010;Conway & Balme, 2016), and it is likely that a spectrum of behaviors occurs even within individual gullies (e.g., Conway et al, 2018b;De Haas et al, 2017).…”

CO 2 sublimation in Martian gullies: laboratory experiments at varied slope angle and regolith grain sizes

“…However, these landforms, which have been dated to millions of years (Reiss et al 2004;Schon et al 2009;Johnsson et al 2014), are incised into consolidated materials including both the ice-rich Latitude Dependent Mantle and bedrock (e.g. Dickson et al 2015;de Haas et al 2017). Erosion of the unconsolidated sublimation lag believed to be on top of the LDM should engender loss of the interstitial ice by sublimation, rendering further sediment available for transport (e.g.…”

Martian gullies: a comprehensive review of observations, mechanisms and insights from Earth analogues

“…Gully-alcoves are generally theatre-shaped depressions, whose upslope extent is located at the hillcrest or mid-slope within the hillslope on which they are located. They can be incised into the bedrock, often exposing numerous metre-scale boulders, or into slope-side deposits, such as the latitude dependant mantle (LDM) or sand (e.g., Aston et al, 2011;de Haas et al, 2018de Haas et al, , 2015ade Haas et al, , 2013Núñez et al, 2016b). The LDM is believed to be an ice-rich mantling unit of which the most recent layers were deposited during climate excursions, which happened in the last few millions of years (see Section 2.3).…”