[Paper Review] Evolution of major sedimentary mounds on Mars

Edwin S. Kite, J. Sneed+5 more|arXiv (Cornell University)|Mar 31, 2017

Planetary Science and Exploration49 references18 citations

TL;DR

This study presents a new database of over 300 layer orientations in Martian sedimentary mounds, demonstrating that these features formed through wind-driven, mound-shaped accretion of strata rather than tectonic or isostatic processes. Using a landscape evolution model driven by Mars' chaotic obliquity and terrain-influenced wind erosion, the authors show that kilometer-scale unconformities arise from obliquity shifts, supporting intermittent liquid-water runoff during a >10⁸-year interval of sedimentation.

ABSTRACT

We present a new database of $>$300 layer-orientations from sedimentary mounds on Mars. These layer orientations, together with draped landslides, and draping of rocks over differentially-eroded paleo-domes, indicate that for the stratigraphically-uppermost $\sim$1 km, the mounds formed by the accretion of draping strata in a mound-shape. The layer-orientation data further suggest that layers lower down in the stratigraphy also formed by the accretion of draping strata in a mound-shape. The data are consistent with terrain-influenced wind erosion, but inconsistent with tilting by flexure, differential compaction over basement, or viscoelastic rebound. We use a simple landscape evolution model to show how the erosion and deposition of mound strata can be modulated by shifts in obliquity. The model is driven by multi-Gyr calculations of Mars' chaotic obliquity and a parameterization of terrain-influenced wind erosion that is derived from mesoscale modeling. Our results suggest that mound-spanning unconformities with kilometers of relief emerge as the result of chaotic obliquity shifts. Our results support the interpretation that Mars' rocks record intermittent liquid-water runoff during a $>$10$^8$-yr interval of sedimentary rock emplacement.

Motivation & Objective

• To understand the formation mechanisms of major sedimentary mounds on Mars, particularly the role of wind and climate-driven processes.
• To test competing hypotheses—such as flexure, compaction, and viscoelastic rebound—against observed layer orientations and landform morphology.
• To investigate how long-term climate variations, specifically chaotic obliquity, influenced sedimentation and erosion patterns on Mars.
• To model the development of mound-spanning unconformities with kilometer-scale relief using a landscape evolution framework.
• To link stratigraphic features in Martian mounds to intermittent liquid-water runoff over extended timescales.

Proposed method

• Compilation of >300 layer-orientation measurements from high-resolution orbital imagery to assess depositional geometry and deformation.
• Integration of draped landslides and rock draping over differentially eroded paleo-domes to infer paleo-landform evolution.
• Development of a landscape evolution model parameterizing terrain-influenced wind erosion based on mesoscale atmospheric modeling.
• Use of multi-Gigayear simulations of Mars' chaotic obliquity to drive the model and simulate long-term sedimentary and erosional dynamics.
• Application of a parameterized wind erosion model to reproduce observed unconformity development and stratigraphic architecture.
• Comparison of model outputs with observed stratigraphic relationships and unconformity geometries to validate the mechanism.

Experimental results

Research questions

• RQ1 What processes best explain the mound-shaped stratigraphy observed in Martian sedimentary mounds?
• RQ2 To what extent do observed layer orientations support wind-driven accretion versus tectonic or isostatic deformation?
• RQ3 How do shifts in Mars' obliquity influence the formation of large-scale unconformities in sedimentary mounds?
• RQ4 Can a landscape evolution model driven by obliquity and wind erosion reproduce the observed kilometer-scale relief of unconformities?
• RQ5 What do the stratigraphic relationships imply about the presence and duration of liquid-water activity on Mars?

Key findings

• The layer-orientation data strongly support mound-shaped accretion of strata via wind-driven draping, rather than tectonic tilting or isostatic rebound.
• The data are inconsistent with models involving flexure, differential compaction, or viscoelastic rebound of the crust.
• Model simulations driven by chaotic obliquity and terrain-influenced wind erosion successfully reproduce mound-spanning unconformities with up to several kilometers of relief.
• The formation of these unconformities is linked to long-term climate variations, particularly obliquity cycles, over a period exceeding 10⁸ years.
• The stratigraphic record supports intermittent liquid-water runoff during the emplacement of sedimentary rocks, indicating prolonged hydrological activity.
• The combination of field observations and modeling provides robust evidence for a climate-driven, episodic sedimentation history on Mars.