Document Type

Student Paper

Publication Date

Spring 5-14-2021

Disciplines

Geology | Geomorphology | Other Earth Sciences | The Sun and the Solar System

Description, Abstract, or Artist's Statement

Aeolian process have dominated the lower latitudes of Mars for billions of years. Aeolian landforms can act as records of current and past climates and landscape evolution processes. The etched deposits of Meridiani Planum, a vast suite of layered bedrock extending from southwest Arabia Terra to Schiaparelli crater, have long been noted to have been eroded by aeolian processes. However, little detailed work on the aeolian landforms of Meridiani Planum beyond the Opportunity rover landing site has been done. In this study, I examine wind streaks, aeolian bedforms (including dunes and large ripples), and yardangs in a valley about 370 km northeast of the Opportunity site using CTX, HiRISE, and THEMIS imagery in order to extrapolate past and present wind regimes, and to uncover the processes that have driven landscape evolution in layered bedrock on Mars during the Late Amazonian. I measure the orientations of wind streaks, dune slipfaces, ripples, and yardangs to determine their formative wind directions, and make qualitative observations to determine the processes driving landscape evolution. I find wind streaks and dunes suggestive of northeasterly winds, while ripples and valley-interior yardangs indicate east-southeasterly winds. Sawtooth scarp features, considered here to be yardangs, suggest northerly to easterly winds, though the orientations of these features may be more strongly controlled by scarp orientation than wind direction. Since the large, sawtooth-scarp features likely require the longest timescales to form out of all the landforms examined here, they likely represent the oldest wind regime. Dunes and wind streaks are still active across the
planet, and may represent modern winds. Ripples and valley-interior yardangs are likely of intermediate age. The wind regime, therefore, may have transitioned from northeasterly, to easterly, and back to northeasterly winds. If climate change on Mars is driven by orbital/rotational changes similar to Earth’s Milankovitch cycles, then the landforms in this region may record a full cycle. Examination of HiRISE imagery reveals cliff retreat driven by undercutting enabled by a highly-erodable, high-albedo unit that is also conducive to yardang formation. Sand accumulations are most significant alongside cliffs, and so sand in the region is likely supplied from material weathered off cliffs, sand which can then further abrade and undercut the cliffs. Superposition of material weathered from cliffs on top of ripples implies that cliff retreat continued in this region at least until the period of ripple formation.

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