A revised surface age for the North Polar Layered Deposits of Mars

Landis, M. E.; Byrne, Shane; Daubar, I. J.; Herkenhoff, K. E.; Dundas, C. M.

doi:10.1002/2016gl068434

Cited by 45 publications

(46 citation statements)

References 42 publications

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“…Due to the decrease in mean obliquity at~4.5 Ma, it is thought that this is the time when the NPLD started forming (Levrard et al, 2007) and has since undergone an average of 0.5 mm/year of ice accumulation (Hvidberg et al, 2012;Laskar et al, 2002). Short-term accumulation rates derived from the removal of recent impact craters are an order of magnitude higher (Banks et al, 2010;Herkenhoff & Plaut, 2000;Landis et al, 2016). However, the accumulation of ice mounds within polar craters (Conway et al, 2012) suggests that craters may be a favorable site for preferential ice accumulation, and it is unclear if these accumulation rates reflect the accumulation conditions over the bulk of the NPLD surface and over what time period.…”

Section: /2018je005806mentioning

confidence: 99%

A Migration Model for the Polar Spiral Troughs of Mars

et al. 2019

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Mars' iconic polar spiral troughs are 400–1,000‐m‐deep depressions in the north polar layered deposits. As the north polar layered deposits accumulate, troughs migrate approximately poleward, anti‐parallel to the local wind patterns. Insolation is suspected to drive ice retreat through sublimation. Sublimation at the trough wall produces a growing sublimation lag that modulates further retreat; however, winds move material off the retreating slope faces, thinning the lag. Discontinuities in stratigraphy seen by radar highlight Trough Migration Paths (TMPs), which provide a record of the troughs' position, formation, and evolution to the present day. We investigate two adjacent troughs presently near 87°N to evaluate the mass balance conditions at those sites. We constrain the contribution of insolation‐induced sublimation to the migration in the observed TMPs. We present a phenomenological model that combines our simulations of the sublimation conditions at paleo‐trough surfaces with accumulation rates to create synthetic TMPs that are tunable to the observations. Models using nominal values of lag diffusivity, albedo, and atmospheric water vapor abundance and in which the trough walls have been covered in a lag on the order of millimeters thick and formed ~2.3 Myr ago match the observed trough migration and align with expectations of trough ages. Thicker lags, and/or older troughs, would generate TMPs of constant slope, which does not match the observed paths. We demonstrate the viability of our new theoretical model for predicting conditions that lead to trough migration, allowing us to connect observable TMPs to Martian climate processes.

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Section: /2018je005806mentioning

confidence: 99%

A Migration Model for the Polar Spiral Troughs of Mars

et al. 2019

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“…; Baker and Head ; Landis et al. ), while a smaller set of papers address the effect that secondaries have on the crater populations and derived ages; we focus on that smaller set of papers here.…”

Section: Recent Workmentioning

confidence: 99%

Secondary craters and ejecta across the solar system: Populations and effects on impact‐crater–based chronologies

Bierhaus

McEwen

Robbins

et al. 2018

Meteorit & Planetary Scien

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We review the secondary‐crater research over the past decade, and provide new analyses and simulations that are the first to model an accumulation of a combined primary‐plus‐secondary crater population as discrete cratering events. We develop the secondary populations by using scaling laws to generate ejecta fragments, integrating the trajectories of individual ejecta fragments, noting the location and velocity at impact, and using scaling laws to estimate secondary‐crater diameters given the impact conditions. We also explore the relationship between the impactor size–frequency distribution (SFD) and the resulting secondary‐crater SFD. Our results from these analyses indicate that the “secondary effect” varies from surface to surface and that no single conclusion applies across the solar system nor at any given moment in time—rather, there is a spectrum of outcomes both spatially and temporally, dependent upon target parameters and the impacting population. Surface gravity and escape speed define the spatial distribution of secondaries. A shallow‐sloped impactor SFD will cause proportionally more secondaries than a steeper‐sloped SFD. Accounting for the driving factors that define the magnitude and spatial distribution of secondaries is essential to determine the relative population of secondary craters, and their effect on derived surface ages.

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“…Similarly, Landis et al. () revisited crater modification within the north polar layered deposits (NPLD), and concluded that water ice deposition rates are rapid enough to completely infill 100‐m diameter craters on time scales of centuries.…”

Section: Crater Modificationmentioning

confidence: 99%

“…They attributed these fast crater obliteration timescales to repeated deposition and sublimation of an ice-rich meter-thick mantle that must be occurring during Mars' present-day spin/orbit configuration. Similarly, Landis et al (2016) revisited crater modification within the north polar layered deposits (NPLD), and concluded that water ice deposition rates are rapid enough to completely infill 100-m diameter craters on time scales of centuries.…”

Section: Marsmentioning

confidence: 99%

Dating very young planetary surfaces from crater statistics: A review of issues and challenges

Williams

Bogert

Pathare

et al. 2017

Meteorit & Planetary Scien

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Abstract-Determining the ages of young planetary surfaces relies on using populations of small, often sub-km diameter impact craters due to the higher frequency at which they form. Smaller craters however can be less reliable for estimating ages as their sizefrequency distribution is more susceptible to alteration with debate as to whether they should be used at all. With the current plethora of meter-scale resolution images acquired of the lunar and Martian surfaces, small craters have been widely used to derive model ages to establish the temporal relation of recent geologic events. In this review paper, we discuss the many factors that make smaller craters particularly challenging to use and should be taken into consideration when crater counts are confined to small crater diameters. Establishing confidence in a model age ultimately requires an understanding of the geologic context of the surface being dated as reliability can vary considerably and limitations of the dating technique should be considered in applying ages to any geologic interpretation.

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A revised surface age for the North Polar Layered Deposits of Mars

Cited by 45 publications

References 42 publications

A Migration Model for the Polar Spiral Troughs of Mars

A Migration Model for the Polar Spiral Troughs of Mars

Secondary craters and ejecta across the solar system: Populations and effects on impact‐crater–based chronologies

Dating very young planetary surfaces from crater statistics: A review of issues and challenges

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