wind erosion of layered sediments on mars: the role of...

Wind erosion of layered sediments on Mars: The role of terrain

For submission to ROSES - Solar System Workings 2014 (NNH14ZDA001N-SSW)

1. Table of contents ............................................................................................................0 2. Scientific/Technical/Management ................................................................................1 2.1 Summary .................................................................................................................1 2.2 Goals of the Proposed Study .................................................................................1 2.3 Scientific Background ............................................................................................1 2.3.1. Wind erosion on Mars ...................................................................................1 2.3.2. Slope winds ...................................................................................................3 2.3.3. Formation of sedimentary mounds and moats ..............................................4 2.4 Technical Approach and Methodology ................................................................4 2.4.1. Application of the Mars Regional Atmospheric Modeling System ..............5 2.4.2. Numerical experiments with idealized craters and canyons .........................6 2.4.3. Consideration of the effect of sedimentary infill (sedimentary mounds) .....7 2.4.4. Simulation of slope-eroding winds for geologically realistic terrain ............9 2.4.5. Incorporation of slope winds into landscape evolution model ...................10 2.4.6. Assumptions and caveats ............................................................................12 2.5 Perceived Impact of Proposed Work .................................................................12 2.6 Relevance of Proposed Work ..............................................................................12 2.7 Work Plan ............................................................................................................13 2.8 Personnel and Qualifications .............................................................................14 3. References .....................................................................................................................15 4. Biographical sketches ..................................................................................................22 5. Current and Pending Support ....................................................................................28 6. Budget Justification .....................................................................................................29 6.1.1. Personnel and Work Efforts ............................................................................30 6.1.2. Facilities and Equipment ..................................................................................30 6.2 Budget Details...........................................................................................................31 7. Subcontract to the SETI Institute ............................................................................33

Wind erosion of layered sediments on Mars: the role of terrain

1

2. Scientific/Technical/Management: 2.1 Summary. Slope-enhanced wind erosion is the dominant process shaping layered sediments on Mars today, but there is currently no physical model of the effect of long-term wind erosion on Martian landscape evolution (and vice versa). Moats surrounding sediment mounds with layers exposed around their perimeters, a paucity of small craters on steep slopes, and downslope-oriented yardangs all suggest that wind erosion has defined the outcrop topography of layered sediments such as Gale crater’s mound (Mt. Sharp / Aeolis Mons), and the Valles Marineris interior layered deposits. Coupling between steep slopes and strong winds on Mars emerges from fundamental physical principles, and slope winds are a first-order, model-independent feature of mesoscale circulation(s) on Mars. Similarly, one of the most fundamental observations about the sedimentary record of Mars is that much of it is missing: erosion is ubiquitous, particularly for layered sediments situated within craters and canyons, and erosion/exhumation affects the preservation of records of habitability contained within those layered sediments. Despite the importance of aeolian denudation of layered sediments in craters and canyons on Mars, there is currently no physical model of long-term wind-terrain coupling. We propose to bridge this gap by utilizing mesoscale atmospheric model output to parameterize the effect of slope winds on Martian wind erosion, and incorporating this understanding into a landscape evolution model to probe long-term atmosphere-landscape coupling (including the effects of a past thicker atmosphere). We shall thus obtain:- 1) quantitative constraints on the processes and pattern of terrain-influenced near-surface winds on Mars at atmospheric pressure 6-384 mbar; 2) a parameterization of the effect of terrain on wind-erosion potential at the scale of sedimentary mounds and the craters and canyons that host them; 3) predictions of how topographic change feeds back on the erosive windfield (landscape-windfield co-evolution). Therefore, the proposed work will improve our understanding of atmosphere-surface interaction on both modern and ancient Mars. 2.2 Goal of the proposed study. The objective of the proposed work is to constrain the role of terrain-influenced winds (slope winds) in shaping sediment accumulations on Mars. We calculate long-term erosion potential using the windfield output of mesoscale atmospheric models. Achieving this objective involves the following steps (hypotheses are listed at the heads of the corresponding subsections):- Step 1. Mesoscale numerical experiments with idealized crater/canyon topography (§2.4.2). Step 2. Additional mesoscale runs with sedimentary infill (sediment mounds and sheets) (§2.4.3). Step 3. Compare model output to geological data in complex terrain (§2.4.4). Step 4. Run landscape evolution model incorporating parameterization of mesoscale results (§2.4.5). In order to define a focused, well-posed investigation of appropriate scope for a three-year study, we make several simplifying assumptions, which are explained and justified in §2.4.6.


2

2.3 Scientific background. 2.3.1. Wind erosion on Mars: Wind erosion occurs when surface wind stresses are high enough for saltation, allowing saltating sand-sized particles to strike erodible surfaces [Greeley & Iverson, 1982; Anderson, 1986; Kok et al., 2012]. On Mars, saltating sand-sized particles are in active motion [e.g., Bourke et al., 2008; Chojnacki et al., 2011; Silvestro et al., 2011], at rates that predict aeolian erosion of bedrock at 10-50 µm/yr [Bridges et al., 2012a]. Within the last ~0.1 Ma, wind has mobilized particles ranging from dust aggregates to hematite granules [Sullivan et al., 2008, Golombek et al., 2010], and aeolian abrasion of sedimentary rock has occurred within the last roughly 1-10 Ka [Golombek et al., 2010; Fig. 1]. At Gale crater, rapid retreat of a >2m-high scarp due to aeolian erosion ~80 Ma is required by coincident 3He, 36Ar, and 21Ne exposure ages [Farley et al., 2014]. Rapid exhumation by wind erosion from depths of more than 1-2 meters (the zone of radiation damage) has major implications for the preservation of organic-matter, and MSL’s search for organic matter is now being focused on areas of recent wind exhumation [Grotzinger, 2014]. Rover imaging confirms that rock abrasion is a major geomorphic agent at Gale [Bridges et al., 2014]. These recent findings make a compelling case for aeolian erosion on modern Mars, and cap four decades of research into Martian aeolian bedforms, saltation and aeolian erosion [e.g., Sagan, 1973; Iverson et al., 1975; Ward, 1979; Greeley, 1982; Thomson et al., 2008; de Silva et al. 2010; Montgomery et al., 2012]. Intriguingly, the observed locations of sand transport cannot be reproduced by General Circulation Models (GCMs), which suggests that mesoscale winds (not the regional-to-global winds resolved by GCMs) are responsible for saltation [Chojnacki et al., 2011; Kok et al. 2012; Bridges et al., 2013]. The mesoscale circulation within craters and canyons is dominated by slope winds as a consequence of Mars’ thin atmosphere [e.g. Rafkin & Michaels, 2003; Spiga & Forget, 2009, Vasavada et al., 2012; Tyler & Barnes, 2013, Pla-García et al., 2014]. These high-relief craters and canyons are where most sulfate-bearing sedimentary rocks are found. The high-relief sedimentary mounds of the Valles Marineris, Gale, and the Medusae Fossae Formation, as well as layered dust aggregates on the flanks of large volcanoes, show downslope-oriented yardangs and grooves, a paucity of small craters, and (frequently) ferric-oxide lags - suggesting geologically recent or ongoing wind erosion [Roach et al., 2010]. With erosion rates outpacing cratering for many sedimentary-rock outcrops [Malin et al., 2007], and geologic and

Figure 1. Evidence for slope wind erosion of layered sediments on Mars. Left: blueberry lag from aeolian erosion surrounds 30cm-diameter block ejected from ~1-10 Ka crater [Golombek et al. 2010]. Center: yardangs from Candor Chasma (MOC NA M1301494; 2km across). Right: mesoscale topographic undulations define moats and mounds within the Candor canyon-filling sediments (MOLA topography; image is ~600km across).


3

model estimates agreeing on the potential for many km of cumulative erosion [Armstrong & Leovy, 2005], wind erosion has altered mesoscale topography on Mars in the recent past and has been a first-order control on landscape evolution in sedimentary terrain. However, this process is missing from detailed models of Mars landscape evolution. Aeolian erosion was probably also important earlier in Mars history. Long-term erosion rates are similar whether measured over 100 Myr or 3 Gyr [Golombek et al. 2014], consistent with the hypothesis that recently-active processes have operated at similar rates through the Amazonian. Aeolian deposits represent a volumetrically significant component of the Martian stratigraphic record [Grotzinger & Milliken, 2012; Hayes et al., 2011], including within the strata of the Gale mound [Anderson & Bell, 2010; Kocurek & Ewing, 2012; Milliken et al., 2014]. The Martian stratigraphic record also contains aeolian erosion/deflation surfaces, which are marked by smooth and laterally extensive unconformities / scour surfaces [e.g., Grotzinger et al., 2005; Kerber & Head, 2010; Holt et al., 2010; Okubo, 2010; Fueten et al., 2008; Zabrusky et al., 2012; Zimbelman & Scheidt, 2012, Kite et al., 2014a]. Therefore, geologically recent wind erosion links present-day aeolian activity to the shaping of sedimentary archives extending towards Mars’ more-habitable early period, and may also be a modern analog for a process that has operated (to varying degrees) throughout Mars history. 2.3.2. Slope winds: The early loss of much of Mars’ atmosphere [Lammer et al. 2013] has made Mars a natural laboratory for studying the coupling between terrain and slope-wind erosion. Erosion by liquid water has not been globally significant since the Late Noachian/Early Hesperian [Golombek et al. 2006], and steep basaltic slopes with many km of relief have persisted for Gyr (sedimentary deposits on Mars are much less resistant to abrasion than unweathered basalt; Herkenhoff et al. 2008). Because of the thin atmosphere and weak greenhouse effect, Mars’ surface is close to radiative equilibrium. The combination of high relief, day-night temperature swings of up to 130K, and an atmospheric lapse rate that is smaller than Earth’s (and very poorly coupled to surface temperature) leads to strong

Fig. 2. Annual-maximum wind speed (m/s) within 150km-diameter Gale Crater from MarsWRF simulations, showing that the strongest winds within the crater are associated with steep slopes. This figure is reproduced from Kite et al. [2013b]; underlying runs implemented by Claire E. Newman using the model of Richardson et al. [2007]. The same patterns are found in unpublished MRAMS runs [Moreau et al. 2014]. Black topography contours are spaced at 500m intervals. The winds are extrapolated to 1.5m above the surface using boundary layer similarity theory (the lowest model layer is at ~9m above the surface).


4

diurnally-reversing slope winds [e.g. Kass et al., 2003]. Slope winds are particularly strong within the equatorial craters and canyons that host sedimentary rock mounds, where coriolis effects are weak and relief is particularly high. The coupling between long, steep slopes and strong winds on Mars emerges from basic physical principles and is model-independent [Spiga et al. 2011, Kite et al. 2013b, Moreau et al. 2014, Tyler & Barnes 2014]. The thin atmosphere also allows for strong topographic influences on the large-scale circulation and regional winds [e.g. Savijarvi & Siili, 1993; Zalucha et al., 2010].

Terrestrial slope-wind research has validated semi-analytic treatments of katabatic winds (and drainage flows) that make idealized assumptions about entrainment and topography, but has also shown their limitations, especially in areas of complex topography where strongly nonlinear effects dominate [e.g. Ellison & Turner, 1959; Manins & Sawford, 1979; Parish & Bromwich, 1987; Horst & Doran, 1986; Papadopoulos et al., 1997; Shapiro & Federovich, 2007; Trachte et al., 2010]. Semi-analytic models do not consider long-term changes in atmospheric pressure, inertial-runout effects, or terrain-landscape feedbacks. Small-scale topography-windfield coupling produces sand dunes, but mesoscale topography-windfield coupling has been little-studied in part because slope wind erosion of bedrock is uncommon on Earth [Rohrmann et al., 2013]. There is no simple existing parameterization for slope winds in realistic terrain. This motivates the use of a mesoscale model to develop such a parameterization. The proposed work will bring together the existing knowledge base on wind erosion and on slope winds.

� Figure 3. Examples of layered sediments within mounds, surrounded by moats. Left: At the 30km-diameter Opportunity rover field site, a thin tongue of flat-lying sedimentary sulfates is three-quarters encircled by a moat. Center: Radar cross section of Korolev Crater’s ice mound. Right: Gale Crater, showing central sedimentary mound encircled by moat. Credits: UMSF; ASI/SHARAD/Jack Holt; DLR/ESA. 2.3.3. Formation of sedimentary mounds and moats: Most of Mars’ sulfate-bearing sedimentary rocks are in the form of intra-crater or intra-canyon mounded deposits surrounded by moats. Moats are typically 10-20 km wide. Most researchers suppose that wind erosion is responsible for shaping the moats and mounds [e.g. Murchie et al., 2009; Okubo, 2010; Andrews-Hanna, 2012], and Kite et al. [2013b] propose that slope winds


5

were also important during mound growth and that they are responsible for the outward tilt of the layers that form Mt. Sharp in Gale crater. However, identifying the physical mechanism(s) that account for the development of sedimentary mounds and moats has been challenging because physically motivated parameterizations of the feedback between terrain and slope-wind erosion are lacking. It is this gap that the proposed work will fill. Several processes may contribute to slope-wind erosion:- (i) breakdown of sedimentary layers to wind-transportable fragments by processes associated with chemical transformations, such as weathering and/or volume changes associated with hydration state changes [e.g., Chipera & Vaniman, 2007]; (ii) physical degradation of hillslopes by mass wasting, followed by aeolian removal of talus to maintain steep slopes and allow continued mass wasting; (iii) aeolian erosion of weakly salt-cemented sediments [Shao, 2008]; (iv) aeolian abrasion of bedrock [Wang et al., 2011]. These processes range from transport-limited to detachment-limited, and predict correspondingly different shear-stress dependencies, thresholds for erosion, and mesoscale mound morphologies. 2.4 Technical Approach and Methodology. The brief strong gusts that are responsible for wind erosion occur on a much shorter timescale than the millions of years needed to substantially reshape the topography that steers the gusts. We exploit this decoupling of timescales by running mesoscale atmospheric simulations with

fixed topography, and use the output from a grid of such mesoscale runs to obtain a parameterization for incorporation into a model of topographic change. 2.4.1. Application of the MRAMS (Mars Regional Atmospheric Modeling System). We use MRAMS, which is derived from the terrestrial RAMS code [Pielke et al. 1992] and has been adapted to Mars problems by Co-I Michaels and Collaborator Rafkin. MRAMS was used for entry, descent and landing simulations for the Mars Exploration Rovers, Mars Phoenix, and Mars Science Laboratory [Rafkin et al. 2001; Michaels and Rafkin, 2008, Vasavada et al. 2012] and has also been used in LES mode to study aeolian processes including

Figure 4. South-to-north vertical cross-section across a Valles Marineris canyon as simulated by MRAMS [Rafkin & Michaels, 2003]. Wind speed is shaded, temperature (K) is contoured. Upslope winds are noted along the canyon walls, and compensating subsidence is evidence in the center of the canyon. This compensating flow is poorly represented in semi-analytic models.


6

dust lifting [Fenton & Michaels, 2010]. Because of our focus on dynamics, the aerosol microphysics capabilities of MRAMS [e.g. Michaels 2006] are not used:- instead, dust is specified using a simple, fixed Conrath-𝜈 profile (both dust storm and low-dust conditions will be considered), and water ice is zeroed out, leading to a several-fold improvement in computational speed. Water vapor is included only as a passive, noncondensible tracer, and initial and boundary conditions are chosen self-consistently so that water vapor is never saturated. Consistent with theory for saltation on Mars [Kok et al., 2012], we assume that the density of saltating grains at a given time is insufficient to modify the wind profile within the surface layer.

Horizontal resolution is fixed at 1.5% of the width of the feature being simulated (crater or canyon). Vertical resolution is varied from 2.3 km at the top of the model to 3 m near the ground, with winds near the surface extrapolated to the surface using boundary layer similarity theory. Output is sampled every 60s in order to capture short-lived wind events. Calculations are carried

out on the Midway cluster at U. Chicago. CPU requirements are set by the longest allowable timestep, which decreases with increasing simulated relief. From experience gained during prior collaborations between the PI, the Co-I, and Collaborator Rafkin and using MRAMS [Kite et al. 2011a, 2011b], ≤1 CPU month is required for idealized-terrain runs and ~2 CPU months for Valles Marineris simulations. Midway’s capabilities easily satisfy all our CPU and storage requirements. Periodic boundary conditions in the horizontal dimensions are employed, and an absorbing (“sponge”) upper boundary condition is used. MRAMS is initialized with no motion and spun up until output from successive sols has converged; this requires 2-4 simulated sols (longer for high-pressure runs). Other initial and boundary conditions are varied as specified below. Based on our prior experience with MRAMS [Kite et al. 2011a, 2011b], time for analysis (and not CPU time), sets the length of the project. We set the number of runs, and the number of parameters to vary, based on this prior experience.

2.4.2. Step 1: Numerical experiments with idealized craters and canyons. Initially we use idealized topography to simulate a diurnal cycle of slope winds. We hypothesize that the strongest winds within the crater/canyon occur on the crater/canyon slope and in a ‘runout zone’ on the floor. Input to the model is as follows. Idealized topography for craters is axisymmetric,

Figure 5. Rationale for length scales chosen for the idealized model runs. Blue dots correspond to measurements of nonpolar craters, red squares correspond to measurements of canyons, and green dots correspond to polar ice mounds. Vertical dashed lines correspond to model runs discussed in the text. Gray vertical lines show range of uncertainty in largest-mound width for Valles Marineris/circum-Chryse mounds. Blue dot to left of “G” corresponds to Gale Crater. Width is defined as polygon area divided by the longest straight-line length that can be contained within that polygon. Data from Kite et al. [2013b].


7

using a typical depth:diameter ratio for mound-hosting craters on Mars (3 km depth, a 1km high rim, 20° rim and wall slopes, and a flat floor). Complex craters have a central peak summiting at the elevation of surrounding plains and with 20° slopes. Topography for idealized canyons has prismatic symmetry: a 5km deep trough with no rim, 20° wall slopes, and a flat floor. As appropriate for equatorial layered sediments, there is no coriolis force in the horizontal plane. Diurnal solar forcing is constant and equinoctial (0.50 sols of sunlight) at Mars’ mean distance from the Sun, and local time is tracked in an E-W sense in order to permit a diurnal thermal tide. The surrounding terrain is flat, and the distance to the edge of the model domain is no less than 3000 km including lower-resolution nest grids. Thermal inertia retrievals near strong terrain are unreliable because of slope winds [Spiga et al., 2011]; we adopt a uniform thermal inertia of 230 J m-2 K-1 s-1/2 and uniform albedo 0.23 (corresponding to thermophysical mode C of Putzig et al., 2005). We impose uniform aerodynamic roughness 10-2 m, intermediate between roughnesses calculated for the MPF and PHX sites [Hébrard et al., 2012]. The atmosphere is initialized with a Meridiani-like vertical thermal profile. Output consists of shear velocity (magnitude and direction) at all surface points. From this we derive maps of the mean, maximum and skewness (gustiness) of the windfield. We will vary the scale of the craters and canyons. Based on our survey of mound-hosting craters and canyons on Mars (Fig. 5), the following dimensions are of particular interest: craters 20 km, 40 km, 80 km (reference-case crater), 160 km, and 320 km in diameter; and canyons 60 km, 120 km (reference-case canyon) and 240 km wide. We also run at 2 km crater diameter (simple crater geometry) and 10km canyon (=valley) width, to look for interesting behavior at small length scale as observed in Meteor Crater, Arizona [Kiefer & Zhong, 2011]. Mars’ atmospheric pressure has changed over time [Lammer et al., 2013], and the elevation dependence of modern aeolian activity suggests an atmospheric-pressure dependence of aeolian activity [Geissler et al., 2012], consistent with theory. GCMs predict that a thicker atmosphere would have enabled higher surface wind stresses and thus higher rates of wind erosion [Armstrong & Leovy, 2005], but increasing thermal mass will damp diurnal slope winds. To determine which of these competing effects dominate, we vary atmospheric pressure for our reference crater and reference canyon. Our nominal runs are at 6 mbar (datum) surface pressure. We hypothesize that increased atmospheric pressure will increase the potential for slope-wind erosion. To test this, we will model 24, 96 and 384 mbar atmospheres for the reference crater and reference canyon. This range of pressures spans the range from modern Mars to modern Earth atmospheric density; post-Noachian surface pressures much higher than 384 mbar are unlikely [Lammer et al., 2013, Kite et al. 2014b]. Because of the longer thermal time constant of denser atmospheres, these runs require longer spin-up time, which is accounted for in our CPU-time budget. We investigate the effect of wall slope by carrying out runs at 5° and 30° slope for the reference cases. Low-dust (τIR ~0.3) conditions are assumed for most cases, but to determine the effect of dusty atmospheres on slope winds, we carry out 1 run for the reference crater case under high-dust (τIR ~3) conditions, maintaining a Conrath-ν profile in the vertical. To investigate katabatic-anabatic asymmetries, we carry out one crater run with reversed topography. This geologically unrealistic run will allow us to separate the effect of divergent flow (daytime upslope) from day-night asymmetry for the crater case. In order to link to the general circulation (and the effects of


8

changing orbital forcing), we test the effect on each reference case of a synoptic background wind field of 5 m/s imposed at the boundary (perpendicular to the canyon in the canyon case), and separately to a Coriolis force (f-plane approximation) appropriate for 50° latitude (50° is the approximate latitude of Galle and Spallanzani, which contain the highest-latitude sedimentary mounds on Mars). We carry out one run for each reference case at 0.75 x present-day solar luminosity. Finally, we carry out one sensitivity test for the crater reference case with horizontal resolution fixed at 0.75% of the width of the crater (2x nominal horizontal resolution). Step 1 therefore involves a total of 29 runs. A significant advantage of using smooth, idealized topography is that it allows for a larger timestep, and so more runs for the same computational expense. 2.4.3. Step 2: Consideration of the effect of sedimentary infill (sheets and mounds). In Step 2 we introduce sedimentary infill to the containers (craters/canyons) modeled in Step 1. We consider both sedimentary sheets (filling the crater to uniform elevation; e.g. Asimov crater), and sedimentary mounds. We hypothesize that the presence of a sedimentary mound intensifies wind erosion potential within the crater/canyon. Outputs are the same as for the previous runs. In total, Step 2 involves 45 runs. For a range of crater and canyon geometries, we add flat-topped sheet infill to 50% of the depth of the container, and (separately) mound infill reaching 100% of the container depth at the container center, and reaching 0% elevation at the base of the container-bounding slopes. Mars sedimentary rock mounds tend to steepen near their toe, so we adopt initial mound profiles of the form z ∝ (1 - x2)0.5, where z is normalized elevation and x is distance from the center of symmetry of the container (normalized to the half-width of the flat floor of the container). The geometries

to be considered are {20, 40, 80, 160, 320} km diameter craters, and {60, 120, 240} km wide canyons, the same as in Step 1. Therefore, comparison of the Step 1 and Step 2 output will allow us to test the Step 2 hypothesis. For the 80 km-diameter crater and 120 km-wide canyon, we will also change infill thickness (considering sheet infill 25% and 75% of depth, and mounds 25%, 50%

TOPOGRAPHY MAGNITUDE OFWIND STRESS

+ ++ ++

nonerodible

sediment

locally strong slope windsnear steep slopes

initially uniform

nonerodible

nonerodible

erosion

EMIT

erosion

INITI

ALLY FL

AT:

ONLY IN

FILL

IS ER

ODED:

MORE EROSION

NEAR SLOPES:

weakstrong

strong

Fig. 6. Illustration of stepwise erosion of initially-filled container. MRAMS is used to calculate the magnitude of wind stress given topography, and a simple erosion rule is used to update the topography for the next MRAMS run.


9

and 75% of depth). Observations show that normalized mound width does not keep pace with increasing container size (Fig. 5). We hypothesize that this is caused by slope-wind intensification with increasing crater/canyon size. We will test this hypothesis using the size-dependent results from Steps 1 and 2. Additional runs will include: Stepwise erosion of initially-filled container. We initialize the “reference” crater and canyon completely filled with sediment (smooth initial topography). We define an erosion rate map by making the approximation ∂z/∂t = k (u* – u*c)3 [Kok et al. 2012] with u*c set to 90% of the maximum wind speed experienced anywhere in the model domain during the first run. ∂z/∂t is set to zero for the (basaltic, nonerodible) container and also where u* < u*c. These choices are made to ensure strong landscape-terrain feedback, and a wider range of erosion equations are considered in Step 4. k is adjusted such that the eroded topography differs from the previous topography by at most 20% of the original thickness of sedimentary infill, and the mesoscale model rerun on this altered topography. We repeat this cycle 7 times for the reference crater and 7 times for the reference canyon (14 runs). We hypothesize that this iteration will lead to the emergence of central mounds and moats due to enhanced erosion near the steep walls of the nonerodible container (Fig. 6). As in Step 1, we will carry out a run with synoptic u = 5 m/ for each reference case (2 runs). Motivated by the asymmetric placement of Mt. Sharp / Aeolis Mons within Gale and of Ganges Mensa within Ganges Chasma, we will also investigate asymmetric mound placement (1 simulation for each reference case, with mound center displaced by ¼ of container width) (2 runs). Spatially variable thermophysical properties. We will carry out 1 sensitivity test adapting the reference mound-filled crater simulation by introducing a contrast in albedo and thermal inertia between the sedimentary infill and the nonerodible container, using TES thermal inertia and albedo averages for Mt. Sharp / Aeolis Mons for the sedimentary infill [Pelkey & Jakosky, 2002; Anderson & Bell, 2010], and thermophysical mode B [Putzig et al., 2005] for the nonerodible container. (1 run) Erosion rates increase dramatically with wind speed, so that the pattern of erosion reflects the strongest gusts [Anderson, 1986; Bridges et al., 2014]. By regressing shear stress output from Steps 1 and 2 against input topography, we shall determine the explanatory power of the following topographic parameters in explaining patterns of maximum shear stress magnitude, 99th-percentile shear stress magnitude, and 95th-percentile shear stress magnitude across high-relief Martian landscapes: (a) local slope, (b) drainage area, (c) vertical distance and (d) horizontal distance from furthest ridge, (e) vertical and (f) horizontal distance from nearest ridge, (g) potential energy in drainage area assuming uniform thickness of drainage flow, (h) all of the above criteria but with inverted topography (for upslope winds). We shall use these results together with an information criterion (for example the Aikake information criterion) to select a parameterization with an appropriate number of independent variables (some of the variables listed are not independent). Finally, we will compare the results to predictions from hydraulic (semi-analytic) theory [Manins & Sawford, 1979]. Alongside this empirical approach (essentially multivariate regression), we will attempt to develop a physical theory to account for the numerical output.


10

2.4.4. Step 3: Simulation of slope-eroding winds for geologically realistic terrain. For layered sediments in Candor Chasma, we hypothesize that the strongest wind stresses occur in terrain that has undergone the highest rates of geologically recent erosion. The floor of Candor Chasma is a sedimentary outcrop with very few impact craters, indicating high rates of geologically recent erosion [Malin et al., 2007]. Therefore Candor Chasma is a suitable site to compare our wind/erosion models to geologic constraints on resurfacing. We will simulate winds at Candor Chasma using 4-5 nested grids forced at the outermost (hemispheric) nest by the NASA Ames Mars GCM. To constrain wind erosion, we require four-season 24-hour output (Ls = 0, 90, 180, 270), climatological dust for each season, and no water cycle. Mesoscale output generated for mission support purposes does not satisfy these criteria. We will employ the full wind speed history to compute wind erosion for the detachment limited case [e.g., Wang et al., 2011], making the simplifying approximation ∂z/∂t ∝ (u* – u*c)α with α = 3 [Kok et al., 2012] and setting u*c to the threshold for saltation for 0.1 mm-diameter grains. Here, z is topography, t is time, and u* is shear velocity. This calculation will allow us to determine whether nighttime winds, daytime winds, or both are important for wind erosion, and also to determine whether erosion rate can be approximated as a function of the maximum wind speed only. We will also carry out 1 control experiment at perihelion season using zero wind at the outermost model boundaries in order to isolate the contribution of the general circulation to wind erosion. (Total: 5 experiments for Task 3). The hypothesis of a correlation between wind-erosion potential and erosion rate is testable using existing CTX and HiRISE images of Candor Chasma that are available in the PDS. When erosion rates are high, small-crater frequency is inversely proportional to crater-obliteration rate [e.g., Smith et al., 2008; Kite et al., 2013c]. Published crater-counts for Mars layered sediments confirm that sufficient craters are present for analysis, show the expected shallowing of the crater-size frequency curve expected for wind erosion [Sefton-Nash et al., 2014; Kite et al., 2013c], and suggest a mean erosion rate of (0.1 – 1)µm/yr over the ~10 Myr recorded by the crater population [e.g.

Crater Diameter (km)

NC

rate

rs (>

Dia

met

er)/k

m2

Erosion Rate:

10 −9 m/yr10 −8 m/yr10 −7 m/yr

10 −6 m/yr10 −5 m/yr10 −4 m/yr10 −3 m/yr

10−2 10−110−6

10−4

10−2

100

102

Ivanov PF,Hartmann+Neukum CFHartmann PF,Hartmann05 CFBest fitData

Figure 7. To show that crater counts on Mars sedimentary rocks are adequate to constrain crater-obliteration rates. The crater size-frequency distribution is too shallow to represent a single formation age, but is consistent with the Bayesian best fit steady-state erosional resurfacing rate of ~0.2 µm/yr, using the Hartmann Production Function (PF) and the Hartmann [2005] Chronology Function (CF). This is consistent with previous estimates [Smith et al., 2008], and slower than aeolian bedrock abrasion rates on Earth (3-2000 (µm/yr; Rohrmann et al., 2013). Crater counts are summed from Sefton-Nash et al [2014] .


11

Fig. 7; Smith et al., 2008]. Because converting crater size-frequency curves to an absolute erosion rate requires knowledge of the average Mars impact flux over the time period of erosion, we consider this technique to provide only relative (rather than absolute) estimates of erosion rate (there are currently factor-of-four uncertainties in the current Mars impact flux; e.g. Daubar et al., 2013, 2014). Crater size-frequency distributions will be collated (for sedimentary rock outcrops only, and excluding areas of obvious mass wasting and landslides) using a CTX basemap and selected HiRISE images. Based on the statistics of the crater count shown in Fig. 7 (area ~ 110 km2), and based on inspection of HiRISE browse images, 8-10 full-resolution HiRISE images will be sufficient (>100 full-resolution HiRISE images are available for Candor Chasma). HiRISE images will be selected on the basis of the MRAMS outputs in order to span a range of predicted erosion rates. We will supplement the HiRISE counts with a complete count on a 6 meter-per-pixel CTX mosaic. Candor Chasma’s sedimentary rock area is 7 x 104 km2, so the CTX mosaic crater count will only require as much time as ~1 HiRISE image. Our approach to obtaining crater-obliteration rates from crater counts uses Bayesian fitting [Kite et al., 2013c]. Bayesian fitting has the advantage that size bins containing a small number of craters can contribute to the fit, whereas they are usually discarded when N0.5 error bars are incorporated (Fig. 7). Our focus on wind stress magnitude is complementary to a previous study comparing yardang orientations to GCM-predicted wind direction [Sefton-Nash et al., 2014]. We will bin craters according to the predicted erosion rate corresponding to that crater’s location, which will allow us to test the predicted correlation between erosion rate and crater frequency. If the prediction is supported, then the slope of the trend will allow us to fit a proportionality constant ke for the relation ∂z/∂t = ke(u* – u*c)3 (subject to future updates to Mars crater flux from the MRO extended mission), and to explore the possible importance of bedrock mineralogy (e.g. kieserite versus epsomite) in setting crater-obliteration rate. 2.4.5. Step 4: Incorporation of slope winds into landscape evolution model. We hypothesize that slope-wind/terrain feedbacks can explain the “moat-and-mound” topography of layered-sediment-hosting craters and canyons, including Gale Crater’s Mt. Sharp / Aeolis Mons. In this final step we will incorporate a parameterization linking topography to wind erosion as an erosion rule in a landscape evolution model. In order to do this, we will convolve the wind-field parameterization produced in Task 2 with existing theories for sediment transport and wind erosion to calculate the erosion potential as a function of terrain and of the cohesion/abrasion susceptibility of the substrate. The theories employed [Shao, 2008; Kok, 2012] will be appropriate for:- (i) sand movement using physically-realistic saltation mass flux relations [Nickling & McKenna Neumann, 2009; Kok et al., 2012]; (ii) emission of fine-grained particles from soil [Shao, 2008]; (iii) weakly salt-cemented soil, employing the relation u*c = u*c(0) exp(ass) where u*c(0) is the saltation threshold for non-cemented soil, as ~ 0.15, and s is salt concentration in mg g-1 [Shao, 2008] assuming salt concentrations of ~1% [McLennan et al., 2010]; (iv) detachment-limited bedrock abrasion, assuming an abrasion susceptibility (g/g) appropriate for sand transport at impact threshold (2 x 10-6 for modern atmospheric pressure; Bridges et al., 2012). In cases (i) and (iv) we require the velocity distribution of saltating particles for closure (including impact angles). To do this we will utilize the computationally inexpensive model COMSALT, developed by Collaborator Kok [Kok & Renno, 2009], forced by MRAMS boundary-layer output, and assume that the sand supply is sufficient for the saltating


12

boundary layer to reach steady state. In all cases we will assume a fiducial grain diameter of 0.1 mm for abrading particles, but test the sensitivity to (0.2-0.3) mm diameter grains as observed in Gusev crater [Sullivan et al. 2008].

We will then adapt our simple landscape evolution model [Kite et al., 2013b] to implement the erosion rules so obtained. Our model simulates landscape evolution in one horizontal dimension (radius or width) (Fig. 8). It can be initialized with either realistic or idealized topography, and can simulate steady, unsteady or zero deposition. A simple case (steady, uniform deposition; idealized topography) is shown in Fig. 8. Following incorporation of the erosion rule obtained from the mesoscale runs, we will carry out parameter sweeps in the landscape evolution model, emphasizing the zero-deposition case. Landscape evolution models trade decreased detail for the ability to model processes over geological time [Howard 2007, Whipple & Tucker, 1999]. The minimal computational cost of the landscape evolution model allows us to carry out a large number of parameter sweeps investigating both variations in the erosion rule and in the

Figure 8. Top: Preliminary work using landscape evolution model, showing simulated sedimentary mound growth and form for one example of a hypothetical idealized atmosphere-topography feedback (from Kite et al. 2013b). Colored lines correspond to snapshots of the mound surface equally spaced in time (blue being early and red being late). Black line corresponds to the nonerodible “container” topography. Topographic change is the balance of an atmospheric source term and wind erosion. In this hypothetical idealized case, the atmospheric source term is uniform in space and constant in time, and the stratigraphy and geomorphology therefore results solely from slope-wind/terrain coupling. Kite et al. [2013b] provides details of the coupling imposed; the proposed work will supersede this parameterization. Inset plots show (bottom left) the resulting stratigraphy at late time and (bottom right) dip measurements from HiRISE DTMs at the Gale mound. Note that slope-wind enhanced erosion characteristically produces outward (moatward) dips, consistent with observations. Given that this is an idealized model, the similarity to the stratigraphy and layer orientations within the Gale mound (bottom right) is intriguing.


13

crater geometry. These parameter sweeps shall include:- (i) nonerodible container initially overfilled with erodible material; (ii) nonerodible container initially half-filled with erodible material; (iii) wind erosion competing with spatially uniform deposition [Kite et al., 2013b] at steady rates ranging from 10-100 µm/yr [Lewis & Aharonson, 2014]. Each of these parameter sweeps will consist of a wide range of crater and canyon dimensions, synoptic wind speeds, and wall slope angles. In each case, we will remove material from the landscape-evolution model domain as it is detached from the substrate, consistent with the generally small volumes of loose material found adjacent to sedimentary-rock mounds on Mars today [Malin et al. 2007, Anderson & Bell, 2010].

Implementing the mesoscale results as a parameterization in a landscape evolution model will allow us to leverage the relatively small ensemble of idealized mesoscale models (n = 74) to explore a much wider parameter space. Thus we can determine if moats and mounds are generic outcomes of slope wind erosion on Mars (supporting the hypothesis that slope winds can explain the “moat-and-mound” topography of layered-sediment-hosting craters and canyons, including Gale Crater’s Mt. Sharp), or alternatively if special circumstances are required for moats and mounds to form from slope winds (disfavoring the hypothesis). A supplementary test of our Step 4 hypothesis is to see if slope winds reproduce the size-dependence of moat formation (Fig. 5).

Finally, this model will allow study of 2-way mesoscale atmosphere-geomorphology feedbacks on Mars [Kite et al. 2013b, Brothers et al. 2013]. For example, the landscape evolution model will generate a large number of physically motivated predictions for the hypothesis that slope wind/terrain coupling played a significant role in the layer orientations and stratigraphy within sedimentary mounds on Mars (parameter sweep iii above), which can be tested from orbit (with HiRISE stereo DTMs) [e.g. Hore et al., 2014], and by MSL as it ascends the Gale mound [Anderson & Bell, 2010; Thomson et al., 2011; Le Deit et al., 2013; Kite et al., 2013b].

2.4.6 Assumptions and caveats It is worth emphasizing the limitations and assumptions of these modeling methods. First, this is a model-driven proposal whose primary goal is improved understanding of the spatial pattern of long-term wind erosion and landscape evolution. As with terrestrial landscape evolution research [Rohrmann et al., 2013; Portenga & Bierman, 2011], global constraints on the absolute rates of landscape evolution will require input from extensive data analysis, cosmogenic isotopes, laboratory studies, and radiogenic dating, all of which require equipment and personnel beyond the scope of a single Solar System Workings proposal. Second, we assume that armoring (lag formation) processes do not vary strongly across the model domain at the mesoscale. This means that the model is inapplicable to plains traversed by Opportunity, where both slopes (<<1°) and long-term average erosion rates (~1 nm/yr) are small [Golombek et al., 2014] relative to the crater and canyon sites that we focus on (Figs. 2-4; Smith et al., 2008). We accept this limitation because most sedimentary rocks on Mars by volume (including the rocks of Mt. Sharp) are in areas of high relief [Michalski & Niles, 2012], with correspondingly high erosion rates. Finally, we track the energy available for erosion, but we do not track tools responsible for erosion in detail (there is no bookkeeping for abrading clasts). Because our ultimate goal is to develop a landscape evolution model, we assume that over long timescale tools are available (on shorter timescales that are not resolved by the landscape evolution model, peaks in erosion will probably be tied to the passage of supplies of abundant sand). Wind erosion on Mars a long and


14

presumably complex history; we propose to test simple hypotheses about that history, with an eye to enabling richer hypotheses and tests in future. 2.5 Perceived Impact of the Proposed Work. MSL is a mission to a layered sediment mound that has undergone wind erosion that exposes layers [Anderson & Bell, 2010]. Because “[w]ind-induced saltation abrasion […] appears to have been the mechanism responsible for erosion and exhumation of the ancient lakebed sampled by Curiosity,” [Grotzinger, 2014], our proposed work is relevant to understanding geomorphology and sedimentology at Gale Crater. Our landscape evolution modeling is also relevant to Mars 2020. This is because wind exhumation plays a key role in the burial history and thus the pressure-temperature-time history of now-exposed samples, which are key to diagenesis including thermal alteration and radiolysis of organic matter [Farley et al., 2014]. Areas recently exhumed by relatively high rates of wind-induced saltation abrasion are of particular interest for organic-matter preservation [Grotzinger, 2014]. Scientific priorities. The proposed work addresses two of the key questions defined by a recent review paper by members of the Mars sedimentary geology community [Grotzinger et al., 2011]: “How Did Source-to-Sink Sediment Transport Systems Evolve on Mars?,” and “In What Ways Did Martian Sedimentary Rocks Become Modified after Their Deposition?” Wind erosion is a plausible candidate for the large-scale sedimentary-rock exhumation/erosion mechanism identified by Malin & Edgett [2000] as one of the major puzzles of the Mars sedimentary-rock record. Solving this puzzle has implications for the nature of the sedimentary rocks (are they playa evaporites, or indurated loess?), and their diagenetic history [Tosca & Knoll, 2009; Milliken et al., 2010], for the Martian sulfur budget [Michalski and Niles, 2012], and even for tectonics. Large-scale exhumation can trigger tectonic uplift, and this has been proposed for the Qaidam Basin on Earth [Kapp et al., 2011] and for Valles Marineris formation on Mars [Andrews-Hanna, 2012].

Although our study is focused on of wind erosion of layered sediments in the low-latitudes of Mars, the processes being investigated link the low-latitude layered sediments to high-latitude processes and the polar layered deposits. That is because slope-enhanced winds define both the large-scale and small-scale topography of the north polar layered deposits (Chasma Boreale and spiral troughs) and circum-polar ice mounds, and played an important role in ice-mound evolution at both ~101 and 102 km scale [Holt et al., 2010; Smith & Holt, 2010; Conway et al., 2012; Ewing et al., 2010; Brothers et al., 2013]. 2.6 Relevance of the Proposed Work. Our proposed work will advance knowledge about the effect of the Martian atmosphere on the surface and about the effect of terrain on the atmospheric circulation, and it has implications for the sculpting of ancient layered sediments. Therefore, our proposal is within the scope of Solar System Workings call, specifically “Evolution and modification of surfaces: [… D]evelop theoretical […] bases for understanding [physical] features in the context of the varying conditions through time after formation.” Our proposal is highly relevant to Goals III.A.6 and Goal III.A.2 outlined in the Mars Exploration Program Analysis Group (MEPAG) Science Goals Document (it also addresses issues raised in Goals II.A.4 and III.A.3). Goal III.A.6. is to “Characterize surface-atmosphere interactions on Mars” and Goal IIIA.2. is to “evaluate volcanic, fluvial/laucustrine, hydrothermal, and polar erosion and sedimentation processes that


15

modified the Martian landscape over time.” Our proposal addresses a fundamental atmosphere-surface interaction (wind-induced topographic change, and the feedback on the windfield) that has probably operated throughout Mars history. 2.7 Work Plan.

Activities/milestones Deliverables

Yea

r 1

• Carry out idealized-topography runs, and initiate idealized sedimentary-infill runs.

• Train graduate student on MRAMS analysis. • Begin analysis of idealized-topography mesoscale runs. • Start analysis of Candor Chasma geology.

✓ LPSC presentation on: Slope winds on idealized topography. ✓ Short GRL-length manuscript on: Slope winds on idealized topography and predicted patterns of wind erosion.

Yea

r 2

• Complete idealized sedimentary-infill runs, and carry out realistic-topography runs.

• Complete analysis of Candor Chasma geology, and compare with realistic-topography results.

• Complete analysis of idealized-topography runs and derive parameterization for terrain-induced erosion.

• Incorporate terrain-induced wind erosion parameterization into landscape evolution model.

✓ LPSC presentation on: Slope winds on realistic topography. ✓ Detailed manuscript on: Terrain influence on wind erosion in complex on Mars, including comparison with geology.

Yea

r 3

• Complete parameter sweeps using the landscape evolution model. Analyze the results and implications for erosion of layered sediments on Mars.

✓ LPSC presentation on: Test of the hypothesis that wind erosion cut moats bounding sediment mounds on Mars. ✓ Detailed manuscript on slope-wind erosion/landscape evolution coupling.

2.8 Personnel and Qualifications. (For FTE information, see §6, Budget Justification). PI Edwin Kite is currently a Princeton postdoc and a research associate at the University of Chicago (UChicago); he will be an Assistant Professor at UChicago from 1 Jan 2015. As PI, he will participate to some degree in all aspects of the proposed work and oversee its implementation. Co-I Timothy Michaels will support the execution of the MRAMS model of crater-atmosphere interactions; he will also contribute to analysis of the MRAMS output and to paper-writing. Collaborator Scot Rafkin will assist in the interpretation of the MRAMS model output (Tasks 1 and 2). Collaborator Nathan Bridges will assist with the data-model comparison (Task 3) and in the application of the model to Martian landscape evolution (Task 4). Collaborator Jasper Kok will be responsible for contributing the COMSALT saltation model and assisting in its application using MRAMS forcing and the interpretation of its results (part of Task 4). A graduate student at UChicago will carry out a substantial portion of the geologic analysis, and take part in running and analyzing the MRAMS models. All personnel will participate in interpretation of results. The PI, Co-I, and Collaborator Rafkin have worked together to publish two papers relevant to this proposal and using the same model (Kite, Michaels, Rafkin et al. 2011a; Kite, Rafkin, Michaels et al. 2011b). That work was funded by NASA grants NNX08AN13G and NNX09AN18G.


16

3. References Anderson, R.B., Bell, J.F., 2010, Geologic mapping and characterization of Gale Crater and

implications for its potential as a Mars Science Laboratory landing site. Mars 5, 76-128, doi:10.1555/mars.2010.0004.

Anderson, R.S., 1986, Erosion profiles due to particles entrained by wind: Application of an eolian sediment transport model. Geological Society of America Bulletin 97: 1270-1278.

Andrews-Hanna, J.C., Lewis, K.W., 2011, Early Mars Hydrology: 2. Hydrological evolution in the Noachian and Hesperian epochs. J. Geophys. Res., 116, E02007, doi:10.1029/2010JE003709.

Andrews-Hanna, J.C.A., 2012, The formation of Valles Marineris: 3. Trough formation through super-isostasy, stress, sedimentation, and subsidence. Journal of Geophysical Research – Planets, doi:10.1029/2012JE004059.

Armstrong, JC, and Leovy, CB, 2005, Long term wind erosion on Mars, Icarus, 176, 57-74 DOI: 10.1016/j.icarus.2005.01.005, 2005

Bourke, M. C.; Edgett, K. S.; Cantor, B. A., 2008, Recent aeolian dune change on Mars, Geomorphology, v. 94, iss. 1-2, p. 247-255.

Bridges N. T.; Banks M. E.; Beyer R. A., et al., 2010, Aeolian bedforms, yardangs, and indurated surfaces in the Tharsis Montes as seen by the HiRISE Camera: Evidence for dust aggregates, Icarus, 205, 165-182, DOI: 10.1016/j.icarus.2009.05.017.

Bridges, N.T., et al., 2012a, Planet-wide sand motion on Mars. Geology, 40, 31-34, doi:10.1130/G32373.1.

Bridges, N.T., et al., 2012b, Earth-like sand fluxes on Mars. Nature, 485, 339-342, doi:10.1038/nature11022.

Bridges, Nathan; Geissler, Paul; Silvestro, Simone; Banks, Maria, 2013, Bedform migration on Mars: Current results and future plans, Aeolian Research, Volume 9, p. 133-151.

Bridges, N.T., et al., The rock abrasion record at Gale crater: Mars Science Laboratory results from Bradbury landing to Rocknest, J. Geophys. Res. 119, 1374-1389, doi:10.1002/2013JE004579.

Brothers, T.C., and J.W. Holt, 2013, Korolev Crater, Mars: Growth of a 2-km Thick Ice-Rich Dome Independent of, but Possibly Linked to, the North Polar Layered Deposits, 44th Lunar and Planetary Science Conference, held March 18-22, 2013 in The Woodlands, Texas. LPI Contribution No. 1719, p.3022.

Chipera, S.J., & Vaniman, D.T., 2007, Experimental stability of magnesium sulfate hydrates that may be present on Mars, Geochimica et Cosmochimica Acta, 71, 241-250.

Chojnacki, M., D. M. Burr, J. E. Moersch, and T. I. Michaels, 2011, Orbital Observations of Contemporary Dune Activity in Endeavour Crater, Meridiani Planum, Mars, J. Geophys. Res., 116, E00F19, doi:10.1029/2010JE003675.

Conway, S.J., et al., 2012, Climate-driven deposition of water ice and the formation of mounds in craters in Mars’ North Polar Region. Icarus, doi:10.1016/j.icarus.2012.04.021.

Daubar, I. J.; McEwen, A. S.; Byrne, S.; Kennedy, M. R.; Ivanov, B., 2013, The current martian cratering rate, Icarus, 225, 506-516.

Daubar, I.J., et al., 2014, New dated impacts on Mars and an updated current cratering rate, Eighth International Conference on Mars, abstract #1007.


17

de Silva, S.L., Bailey, J.E., Mandt, K.E., and J-G., Viramonte, 2010. Yardangs in terrestrial ignimbrites: Synergistic remote and field observations on Earth with applications to Mars. Planetary and Space Science, v. 58, Issue 4, p. 459-471

Drube, L., et al., 2010, Magnetic and optical properties of airborne dust and settling rates of dust at the Phoenix landing site. Journal of Geophysical Research, 115, E00E23, doi:10.1029/2009JE003419.

Edgett, K.S., 2005, The sedimentary rocks of Sinus Meridiani: Five key observations from data acquired by the Mars Global Surveyor and Mars Odyssey orbiters, Mars 1, 5-58, 2005, doi:10.1555/mars.2005.0002

Ellison, T.H., Turner, J.S., 1959, Turbidity entrainment in stratified flows. J. Fluid Mech. 6, 423-48.

Ewing, R., Peyret, A-P. B., Kocurek, G., and Bourke, M., 2010, Dune field pattern formation and recent transporting winds in the Olympia Undae Dune Field, north polar region of Mars, J. Geophys. Res. 115, E08005, doi:10.1029/2009JE003526.

Farley, K.A., et al., 2014, In Situ Radiometric and Exposure Age Dating of the Martian Surface, Science 343 (6169), doi: 10.1126/science.1247166.

Fenton, L.K., and Michaels, T.I., 2010, Characterizing the sensitivity of daytime turbulent activity on Mars with the MRAMS LES: Early results, Mars 5, 159-171, doi:10.1555/mars.2010.0007

Ferrier K.L., Huppert K.L., Perron J.T., 2013. Climatic control of bedrock river incision. Nature, v. 496, p. 206-209, doi: 10.1038/nature11982.

Fueten, F.; Stesky, R.; MacKinnon, P.; Hauber, E.; Zegers, T.; Gwinner, K.; Scholten, F.; Neukum, G., 2008, Stratigraphy and structure of interior layered deposits in west Candor Chasma, Mars, from High Resolution Stereo Camera (HRSC) stereo imagery and derived elevations, Journal of Geophysical Research, Volume 113, Issue E10, CiteID E10008

Fueten, F., et al., 2010, Structural analysis of interior layered deposits in Northern Coprates Chasma, Mars. Earth and Planetary Science Letters, 294, 343-356, doi:10.1016/j.epsl.2009.11.004.

Geissler, P. E.; Banks, M. E.; Bridges, N. T.; Silvestro, S.; HiRISE Science Team, 2012, HiRISE Observations of Sand Dune Motion on Mars: Emerging Global Trends, Third International Planetary Dunes Workshop: Remote Sensing and Data Analysis of Planetary Dunes, held June 12-15, 2012 in Flagstaff, Arizona. LPI Contribution No. 1673., p.44-45

Golombek, M. P.; Grant, J. A.; Crumpler, L. S.; Greeley, R.; Arvidson, R. E.; Bell, J. F.; Weitz, C. M.; Sullivan, R.; Christensen, P. R.; Soderblom, L. A.; Squyres, S. W., Erosion rates at the Mars Exploration Rover landing sites and long-term climate change on Mars, Journal of Geophysical Research 111, Issue E12, CiteID E12S10.

Golombek, M., et al., 2010, Constraints on ripple migration at Meridiani Planum from Opportunity and HiRISE observations of fresh craters. Journal of Geophysical Research (Planets), 115, E00F08, doi:10.1029/2010JE003628.

Golombek, M., et al., 2014, Erosion rates and Mars climate, 8th International Conference on Mars, abstract number 1359.

Greeley, R., Iversen, J.D., 1982, Wind as a geological process on Earth, Mars, Venus, and Titan, Cambridge University Press.

Greeley, R., et al., 2006, Gusev crater: Wind-related features and processes observed by the Mars Exploration Rover Spirit, J. Geophys. Res. 111, E02S09, doi:10.1029/2005JE002491


18

Grindrod P.M., et al., 2010, Experimental investigation of the mechanical properties of synthetic magnesium sulfate hydrates: Implications for the strength of hydrated deposits on Mars, Journal of Geophysical Research, 115, Issue E6, CiteID E06012.

Grotzinger, J., et al., 2005, Stratigraphy and sedimentology of a dry to wet eolian depositional system, Burns formation, Meridiani Planum, Mars, Earth and Planetary Science Letters 240, 11–72.

Grotzinger, J., Beaty, D., Dromart, G., Gupta, S., Harris, M., Hurowitz, J., Kocurek, G., McLennan, S., Milliken, R., Ori, G.G., & Sumner D., 2011, Mars Sedimentary Geology: Key Concepts and Outstanding Questions, Astrobiology. 11(1): 77-87. doi:10.1089/ast.2010.0571.

Grotzinger, J.P., Milliken, R.E., 2012. The sedimentary rock record of Mars: Distribution, origins, and global stratigraphy. In: Grotzinger, J.P. (Ed.), Sedimentary Geology of Mars, Special Publications, vol. 102. SEPM (Society for Sedimentary Geology), pp. 1–48

Grotzinger, J.P., 2014, Habitability, organic taphonomy, and the sedimentary record of Mars, Science, 343, 386-7.

Hartmann, William K., 2005, Martian cratering 8: Isochron refinement and the chronology of Mars, Icarus, Volume 174, Issue 2, p. 294-32.

Hayes, A.G., et al., 2011, Reconstruction of eolian bed forms and paleocurrents from cross-bedded strata at Victoria Crater, Meridiani Planum, Mars. Journal of Geophysical Research, Volume 116, CiteID E00F21.

Hébrard, E., et al., 2012, An aerodynamic roughness length map derived from extended Martian rock abundance data, J. Geophys. Res. 117, E04008, doi:10.1029/2011JE003942.

Herkenhoff, K.E. et al., 2008. In situ observations of the physical properties of the martian surface. In: Bell, J. III (Ed.), The Martian Surface – Composition, Mineralogy, and Physical Properties, Cambridge University Press, Cambridge, England, pp. 451–467.

Holt, J.W., et al., 2010, The construction of Chasma Boreale. Nature, 465, 446-449. Hore, A.; Fueten, F.; Flahaut, J.; Stesky, R.; Rossi, A. P.; Hauber, E., 2014, Layer Thickness

Measurements, Structural Analysis, and Mineralogical Investigation of the Ganges Chasma Interior Layered Deposit, Valles Marineris, Mars, 45th Lunar and Planetary Science Conference, held 17-21 March, 2014 at The Woodlands, Texas. LPI Contribution No. 1777, p.1577.

Horst, T. W., Doran, J. C., 1986, Nocturnal drainage flow on simple slopes. Boundary-Layer Meteorology, 34, 263-286

Howard, A. D., 2007, Simulating the development of martian highland landscapes through the interaction of impact cratering, fluvial erosion, and variable hydrologic forcing, Geomorphology, 91, 332-363.

Iversen, J.D., Greeley, R., White, B.R., & Pollack, J.B., (1982), Eolian erosion of Martian surface: 1. Erosion rate similitude, Icarus, Volume: 26 Issue: 3 Pages: 321-331 doi: 10.1016/0019-1035(75)90175-X

Kapp, P. et al., 2011, Wind erosion in the Qaidam basin, central Asia: implications for tectonics, paleoclimate, and the source of the Loess Plateau, GSA Today, v. 21, no. 4/5, doi: 10.1130/GSATG99A.1 pp 4-10.

Kass DM; Schofield JT; Michaels TI; et al., 2003, Analysis of atmospheric mesoscale models for entry, descent, and landing, J. Geophys. Res. Planets, 108(E12), 8090. doi: 10.1029/2003JE002065.


19

Kerber, L., & Head, J.W., 2010, The age of the Medusae Fossae Formation: Evidence of Hesperian emplacement from crater morphology, stratigraphy, and ancient lava contacts, Icarus, 206, 669-684, doi: 10.1016/j.icarus.2009.10.001.

Kiefer, M. T.; Zhong, S., 2011, An idealized modeling study of nocturnal cooling processes inside a small enclosed basin, Journal of Geophysical Research, Volume 116, Issue D20, CiteID D20127.

Kite, E.S.; Michaels, Timothy I.; Rafkin, Scot; Manga, Michael; Dietrich, William E., 2011a, Localized precipitation and runoff on Mars, Journal of Geophysical Research, Volume 116, Issue E7, CiteID E07002

Kite, E.S.; Rafkin, Scot; Michaels, Timothy I.; Dietrich, William E.; Manga, 2011b, Chaos terrain, storms, and past climate on Mars, Journal of Geophysical Research, Volume 116, Issue E10, CiteID E10002

Kite, E.S., Halevy, I., Kahre, M.A., Wolff, M.J., Manga, M., 2013a, Seasonal melting and the formation of sedimentary rocks on Mars, with predictions for the Gale Crater mound. Icarus, 223, 181-210.

Kite, E.S., Lewis, K.W., Lamb, M.P., Newman, C.E., & Richardson, M.I., 2013b, Growth and form of the mound in Gale Crater, Mars: Slope-wind enhanced erosion and transport. Geology, 41. 543-546.

Kite, E.S., Lucas, A., & C.I. Fassett, 2013c, Pacing Early Mars river activity: Embedded craters in the Aeolis Dorsa region imply river activity spanned ≳(1-20) Myr, Icarus, 225, 850-855.

Kite, E.S., Howard, A., Lucas, A., Armstrong, J.C., Aharonson, O., & Lamb, M.P., 2014a, Stratigraphy of Aeolis Dorsa, Mars: resolving the great drying of Mars, Lunar and Planetary Science Conference.

Kite, E.S., Williams, J.-P., Lucas, A., & Aharonson, O., 2014, Paleopressure of Mars' atmosphere from small ancient craters, Nature Geoscience, 7, 335-339.

Knoll, A.H., et al., 2008, Veneers, rinds, and fracture fills: Relatively late alteration of sedimentary rocks at Meridiani Planum, Mars. Journal of Geophysical Research, Volume 113, Issue E6, CiteID E06S16.

Kocurek, G. and Ewing, R.C., 2012, Source-To-Sink: An Earth/Mars Comparison of Boundary Conditions for Aeolian Dune Systems. J. Grotzinger and R. Milliken (eds.), Sedimentary Geology on Mars. SEPM Special Publication. ISBN: 978-1-56576-312-8

Kok, J.F., Parteli, E.J.R., Michaels, T.I., and Karam, D. B., 2012, The physics of wind-blown sand and dust. Reports on Progress in Physics, 75, 106901.

Kok, J.F., and Renno, N., A comprehensive numerical model of steady state saltation (COMSALT), Journal of Geophysical Research: Atmospheres, Volume 114, Issue D17, CiteID D17204.

Lammer, H., et al., 2013, Outgassing History and Escape of the Martian Atmosphere and Water Inventory, Space Science Reviews, January 2013, Volume 174, Issue 1-4, pp 113-154.

Le Deit, L., et al., 2013, Sequence of infilling events in Gale Crater, Mars: Results from morphology, stratigraphy, and mineralogy, Journal of Geophysical Research: Planets, 118, 2439-2473.

Lewis, K., and Aharonson, O., 2014, Occurrence and origin of rhythmic sedimentary rocks on Mars, J. Geophys. Res. Planets 119, 1432-1457.

Lu, H., and Shao, Y., 1999, A new model for dust emission by saltation bombardment. Journal of Geophysical Research, 104, 16,827-16,842.


20

Malin, M.C. and Edgett, K.S., 2000, Sedimentary Rocks of Early Mars. Science, 290,1927-1937, doi:10.1126/science.290.5498.1927.

Malin, M.C., et al., 2007, Context Camera Investigation on board the Mars Reconnaissance Orbiter, J. Geophys. Res, 112, E05S04, doi:10.1029/2006JE002808.

Manins, P. C., Sawford, B. L., 1987, A model of katabatic winds. Journal of Atmospheric Sciences, 36, 4, pp.619-630.

McLennan, S. M.; Boynton, W. V.; Karunatillake, S.; Hahn, B. C.; Taylor, G. J.; Mars Odyssey GRS Team, 2010, Distribution of Sulfur on the Surface of Mars Determined by the 2001 Mars Odyssey Gamma Ray Spectrometer, 41st Lunar and Planetary Science Conference, held March 1-5, 2010 in The Woodlands, Texas. LPI Contribution No. 1533, p.2174.

Metz, J.M., et al., 2009, Sulfate-Rich Eolian and Wet Interdune Deposits, Erebus Crater, Meridiani Planum, Mars. Journal of Sedimentary Research, 79, 247-264, doi:10.2110/jsr.2009.033.

Michalski, J.R. and Niles, P.B., 2012, An atmospheric origin of Martian Interior Layered Deposits (ILDs): Links to climate change and the global sulfur cycle. Geology, 40, 419-422, doi:10.1130/G32971.1.

Michaels, T. I., A. Colaprete, and S. C. R. Rafkin, 2006, Significant vertical water transport by mountain-induced circulations on Mars, Geophys. Res. Lett., 33, L16201, doi:10.1029/2006GL026562.

Michaels, T. I., and S. C. R. Rafkin, 2008a, Meteorological predictions for candidate 2007 Phoenix Mars Lander sites using the Mars Regional Atmospheric Modeling System (MRAMS), J. Geophys. Res., 113, E00A07, doi:10.1029/2007JE003013

Milkovich, Sarah M.; Plaut, Jeffrey J., 2008, Martian South Polar Layered Deposit stratigraphy and implications for accumulation history, Journal of Geophysical Research, Volume 113, Issue E6, CiteID E06007

Milliken, R.E., Grotzinger, J.P., Thomson, B.J., 2010, Paleoclimate of Mars as captured by the stratigraphic record in Gale Crater. Geophysical Research Letters, 370, L04201, doi:10.1029/2009GL041870.

Milliken, R. E.; Ewing, R. C.; Fischer, W. W.; Hurowitz, J., 2014, Wind-blown sandstones cemented by sulfate and clay minerals in Gale Crater, Mars, Geophysical Research Letters 41, 1149-1154.

Montgomery, D.R., Bandfield, J.L., & Becker, S.K., 2012, Periodic bedrock ridges on Mars, J. Geophys. Res. 117, E03005, DOI: 10.1029/2011JE003970.

Morgan, A., A.D. Howard, D.E.J. Hobley, J.M. Moore, W.E. Dietrich, R.M.E. Williams, D.M. Burr, J.A. Grant, S.A. Wilson, Y. Matsubara, 2014, Sedimentology and climatic environment of alluvial fans in the martian Saheki crater and a comparison with terrestrial fans in the Atacama Desert, Icarus 229, 131-156.

Murchie, Scott; Roach, Leah; Seelos, Frank; Milliken, Ralph; Mustard, John; Arvidson, Raymond; Wiseman, Sandra; Lichtenberg, Kimberly; Andrews-Hanna, Jeffrey; Bishop, Janice; Bibring, Jean-Pierre; Parente, Mario; Morris, Richard, 2009, Evidence for the origin of layered deposits in Candor Chasma, Mars, from mineral composition and hydrologic modeling, Journal of Geophysical Research, Volume 114, Issue E12, CiteID E00D05 (JGRE Homepage)

Nickling, W.G., 1984, The stabilizing role of bonding agents on the entrainment of sediment by wind. Sedimentology, 31(1), 111-117. doi: 10.1111/j.1365-3091.1984.tb00726.x.


21

Nickling, W.G., and McKenna Neumann, C., 2009, Aeolian sediment transport, pp. 517-555 in A.J. Parsons, A.D. Abrahams (eds.), Geomorphology of Desert Environments, 2nd ed., 517, DOI 10.1007/978-1-4020-5719-9 17, c Springer Science+Business Media B.V. 2009

Okubo, Chris H., 2010, Structural geology of Amazonian-aged layered sedimentary deposits in southwest Candor Chasma, Mars, Icarus 207, 210-225.

Papadopoulos KH, Helmis CG, Soilemes AT, Kalogiros J, Papageorgas PG, Asimakopoulos DN, 1997, The structure of katabatic flows down a simple slope, Q J. R. Meteorol. Soc. 123, 1581–1601

Parish, T.R., Bromwich, D.H., 1987, The surface windfield over the Antarctic ice sheets. Nature 328, 51-54, doi: 10.1038/328051a0.

Pelkey, Shannon M.; Jakosky, Bruce M., 2002, Surficial Geologic Surveys of Gale Crater and Melas Chasma, Mars: Integration of Remote-Sensing Data, Icarus, Volume 160, Issue 2, p. 228-257.

Pielke, R. A., et al., 1992, A comprehensive meteorological modeling system—RAMS, Meteorol. Atmos. Phys., 49, 69–91, doi:10.1007/BF01025401.

Pla-Garcia, J. et al., 2014, Preliminary Interpretation of the Meteorological Gale Environment Cycle Year Through Mars Science Laboratory Rover Environmental Monitoring Station Observations and Mesoscale Modeling, EGU General Assembly 2014, held 27 April - 2 May, 2014 in Vienna, Austria, id.12836.

Portenga, E.W., & Bierman, P.R. 2011, Understanding Earth’s eroding surface with 10Be, GSA Today, DOI: 10.1130/G111A.1.

Putzig, Nathaniel E.; Mellon, Michael T.; Kretke, Katherine A.; Arvidson, Raymond E., 2005, Global thermal inertia and surface properties of Mars from the MGS mapping mission, Icarus, Volume 173, Issue 2, p. 325-341.

Rafkin, S. C. R., R. M. Haberle, and T. I. Michaels, 2001, The Mars Regional Atmospheric Modeling System (MRAMS): Model description and selected simulations, Icarus, 151, 228–256, doi:10.1006/icar.2001.6605

Rafkin, S.C.R., Michaels, T.I., 2003, Meteorological predictions for 2003 Mars Exploration Rover high-priority landing sites. Journal of Geophysical Research (Planets), 108, 8091, doi:10.1029/2002JE002027.

Moreau, A.J.M., R.M. Haberle, S.C.R Rafkin, M.A. Kahre, and J.L. Hollingsworth, 2014, Dust erosion and sedimentation patterns in Gale Crater as simulated by the Mars Regional Atmospheric Modeling System (MRAMS), Eighth International Conference on Mars, abstract #1430.

Richardson, Mark I.; Toigo, Anthony D.; Newman, Claire E., 2007, PlanetWRF: A general purpose, local to global numerical model for planetary atmospheric and climate dynamics, Journal of Geophysical Research, vol. 112, issue E9, p. E09001.

Roach, Leah H.; Mustard, John F.; Lane, Melissa D.; Bishop, Janice L.; Murchie, Scott L., 2010, Diagenetic haematite and sulfate assemblages in Valles Marineris, Icarus 207(2), 659-674.

Rohrmann, Alexander; Heermance, Richard; Kapp, Paul; Cai, Fulong (2013), Wind as the primary driver of erosion in the Qaidam Basin, China, Earth and Planetary Science Letters 374, 1-10.

Sagan, C., 1973, Sandstorms and eolian erosion on Mars., Journal of Geophysical Research, 78, p. 4155-4161.


22

Savijarvi, H., Siili, T., 1993, The Martian slope winds and the nocturnal PBL jet. Journal of the Atmospheric Sciences, 50, 77-88. Hellas and Argyre regions. Planetary and Space Science, 47, 951-970.

Sefton-Nash, E.; Teanby, N. A.; Newman, C.; Clancy, R. A.; Richardson, M. I., 2014, Constraints on Mars' recent equatorial wind regimes from layered deposits and comparison with general circulation model results, Icarus, 230, 81-95.

Shao, Y., 2008, Physics and modeling of wind erosion, 2nd revised and expanded edition, Springr.

Shapiro, A., and Federovich, E., 2007, Katabatic flow along a differentially cooled sloping surface, J. Fluid Mech., 571, 149–175, doi:10.1017/S0022112006003302

Siili, T., Haberle, R.M., Murphy, J.R., Savijarvi, H., 1999, Modelling of the combined late-‐winter ice cap edge and slope winds in Mars’

Silvestro S.; Vaz D. A.; Fenton L. K.; et al., 2011, Active aeolian processes on Mars: A regional study in Arabia and Meridiani Terrae, Geophys. Res. Lett., 38, L20201 DOI: 10.1029/2011GL048955.

Smith, M.R., Gillespie, A.R., and Montgomery, D.R., 2008, Effect of obliteration on crater-count chronologies for Martian surfaces, Geophys. Res. Lett. 35, L1202, doi:10.1029/2008GL033538

Smith, I.B., Holt, J.W., 2010, Onset and migration of spiral troughs on Mars revealed by orbital radar. Nature, 465, 450-453.

Spiga, A. and Forget, F., 2009, A new model to simulate the Martian mesoscale and microscale atmospheric circulation: Validation and first results. Journal of Geophysical Research (Planets), 114(E13), E02009, doi:10.1029/2008JE003242.

Spiga, A., F. Forget, J.-B. Madeleine, L. Montabone, S.R. Lewis, E. Millour, 2011, The impact of martian mesoscale winds on surface temperature and on the determination of thermal inertia, Icarus, 212, 504-519

Spiga, A. and S.R. Lewis, 2010, Martian mesoscale and microscale wind variability of relevance for dust lifting, Mars Journal, 5, 146-158

Squyres, S.W., and the Athena Science Team, 2012, Ancient Impact and Aqueous Processes at Endeavour Crater, Mars. Science, 336 (6081), 570-576, doi:10.1126/science.1220476.

Sullivan, R., et al., Wind-driven particle mobility on Mars: Insights from Mars Exploration Rover observations at ``El Dorado'' and surroundings at Gusev Crater. Journal of Geophysical Research, 113(E6), E06S07.

Thomson, B.J., Bridges, N.T., Greleey, R., 2008, Rock abrasion features in the Columbia Hills, Mars, J. Geophys. Res., 113(E8), E08010, doi: 10.1029/2007JE003018.

Thomson, B.J., et al., 2011, Constraints on the origin and evolution of the layered mound in Gale Crater, Mars using Mars Reconnaissance Orbiter data. Icarus, 214, 413 – 432.

Tosca, Nicholas J.; Knoll, Andrew H., 2009, Juvenile chemical sediments and the long term persistence of water at the surface of Mars, Earth and Planetary Science Letters, Volume 286, Issue 3-4, p. 379-386.

Trachte, K., Nauss, T., Bendix, J., 2010, The impact of different terrain configurations on the formation and dynamics of katabatic flows: idealized case studies. Boundary-Layer Meteorology, 134, 307-325.

Tyler, D., & J.R. Barnes (2014), The diurnal surface pressure cycle in Gale crater, Eighth International Conference on Mars, Pasadena, CA, abstract #1335.


23

Vasavada, A., et al. (2012), Assessment of Environments for Mars Science Laboratory Entry, Descent, and Surface Operations, Space Sci. Rev. 170, 793-835.

Wang, Z.-T., Wang, H.-T., Niu, Q.-H., Dong, Z.-B. and Wang, T., 2011, Abrasion of yardangs. Physical Review E, 84, 031304.

Ward, W.A., 1979, Yardangs on Mars: Evidence of Recent Wind Erosion, J. Geophys. Res., 84 (B14, 8147-8166, doi:10.1029/JB084iB14p08147.

Weitz, C. M., E. Z. Noe Dobrea, M. D. Lane, and A. Knudson (2014), Geologic relationships between gray hematite, sulfates, and clays in Capri Chasma, J. Geophys. Res., doi:10.1029/2012JE004092.

Whipple, Kelin X.; Tucker, Gregory E., 1999, Dynamics of the stream-power river incision model: Implications for height limits of mountain ranges, landscape response timescales, and research needs, Journal of Geophysical Research: Solid Earth, Volume 104, Issue B8, pp. 17,661-17,674.

Zabrusky, K., Andrews-Hanna, J.C., & Wiseman, S.M., 2012, Reconstructing the distribution and depositional history of the sedimentary deposits of Arabia Terra, Mars, Icarus 220, 311-330.

Zalucha, A. M., R. A. Plumb, and R. J. Wilson, 2010, An Analysis of the Effect of Topography on the Martian Hadley Cells, Journal of the Atmospheric Sciences, 67, 673, doi: 10.1175/2009JAS3130.1.

Ye, Z.J., Segal, M., Pielke, R.A., 1990, A comparative study of daytime thermally induced upslope flow on Mars and Earth. Journal of the Atmospheric Sciences, 47, 612-628.

Zimbelman, J.R., Scheidt, S.P., 2012, Hesperian Age for Western Medusae Fossae Formation, Mars. Science, doi: 10.1126/science.1221094.

wind erosion of layered sediments on mars: the role of...

Documents