Constraining Possible Glacial Reworking of Ancient Fluvial Channels on the Dichotomy Boundary at Equatorial Regions, Mars
Abstract
Introduction: Glacial erosion processes on the martian dichotomy boundary during the Hesperian and Amazonian periods has not been widely studied and is poorly constrained. We identify possible glacial forms and reworking of previous fluvial channels on the low-latitude portion of the dichotomy boundary near Gale Crater. Using image analysis, we compiled morphometric data associated with these forms. Here we report on a test case lobate form extracted during our analysis.
Methods: CTX DEM's were generated for a ~3,300 km surrounding Gale crater. Lobate forms (Fig. 1) were identified and mapped and morphometric data extracted using ArcGIS along transect on the transverse axes. Numerical modeling used possible past thickness for a rock glacier ranging from a 35/65 to 50/50 mix of basaltic rock and water ice. Estimated thickness and temperature ranges were used to calculate basal shear stress and strain flow rates using the Glen-Nye Flow Law for a valley profile cross-section. Comparisons were made to a quadratic (parabolic) U-shape, typical for glacial valleys and the profile form power law (y=axb). Results: Basal shear stress for the test lobate feature yielded 607 kPa to 153 kPa (35/50 mix) and 789 kPa to 199 kPa (50/50 mix). The flow rate was .01 m/yr for 35/50 mix at -50°C and .02 m/yr for the 50/50 mix. At 0°C, flow rates were 20 m/yr for the 35/65 mix and 44 m/yr for the 50/50 mix. Cross section power law analysis yielded a b value of 2.1. Interpretation: Calculated flow rates are consistent with that of rock glaciers and glacially modified valleys. Valley cross-sections indicate that they have undergone glacial modification with b values (1.5-2.5) indicating that this valley was glacially formed. Conclusion: Numerical modeling yielded striking evidence for what appears to be rock glaciers. Initial observations pervasive evidence of parallel non-anastomosing channels, possibly young fluvial channels and cross cutting remnant channels.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMP038...02W
- Keywords:
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- 1039 Alteration and weathering processes;
- GEOCHEMISTRY;
- 1825 Geomorphology: fluvial;
- HYDROLOGY;
- 5416 Glaciation;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 5419 Hydrology and fluvial processes;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS