Fluvial activity in the Northeast Syrtis Major region and its link to glacial processes in the Hesperian

Connor Matherne1, J.R. Skok2, J.F. Mustard3, Suniti Karunatillake1 1. Department of Geology and Geophysics, Louisiana State University 2. SETI Institute, 3. Department of Geological Sciences, Brown University Introduction Results and Discussion Conclusions

The geology of the northeast edge of the Syrtis Major volcanic • The diffuse source morphology suggests a precipitation origin complex records a diverse history of early Mars. This region of the system’s water (Fig. 3A) contains a stratigraphic record that spans from the period of the • The outlet channel is inconsistent with current topography and Noachian to the Amazonian [1]. We identify a channel and basin would require significant erosion on the southeast edge of the system (Fig. 2) that straddles this divide and attempt to answer the basin or a temporary paleo ice dam (Fig. 2, 5B) following: • A large ice sheet would halt the flow of the lava in order to 1. What are the likeliest hydrological sources for the upland source preserve the basin and prevent infilling of volcanics (Fig. 5A) channels? (Fig. 3) 2. What enabled basin drainage via topographically higher outlet channels, despite the existence of a topographically lower potential outlet to the southeast? (Fig. 2) 3. What preserved the basin as an isolated depression at the terminus of a large volcanic field? (Fig. 4) 4. To what extent do the responses to the preceding questions suggest glacial activity at this geologic transition zone? (Fig. 5)

Figure 3. Upland source channel terrain with lightly eroded braided channels on volcanic lava fields. Figure 1. The regional context of Northeast Syrtis, Mars MOLA globe shows (Background CTX mosaic with colored HRSC DEM overlay, insets are HiRISE images) the location of the underlying image (black box). The region is located at the • Flow channels follow topography (Fig. 3A) until reaching the mesa (Fig. 3B) Northern edge of the early Hesperian, Syrtis Major volcanic flows. The -3050 Figure 5. Minimum required extent of ice cover for the morphological m contour line cuts through the eastern section of our focus area and marks a • Once on the mesa, they diverge into two channels observations. (Background CTX Mosaic with colored HRSC DEM overlay) dichotomy boundary around Isidis and the Northern Lowlands. • One goes east into the basin over sulfates with a boxwork texture (Fig. 3C) Collectively, these observations suggest late-stage, glaciofluvial Methods • The other channel travels off the mesa the south causing erosion (Fig. 3D) processes in the Northeast Syrtis region with a basin preserving ice • The edges of the volcanic flows are highly irregular with steep cliffs (Fig. 3E) sheet and an episodic ice dam over 1 km thick (Fig. 5). Surface morphology and topography was assessed using cameras, Regional glaciation has been suggested in this location before [12], altimeters, and spectrometers known as CTX, HiRISE, MOLA, and however, we are able to place more specific constraints on the HRSC [2,3,4,5]. Local topography determined using HRSC derived western portion of the ice sheet based on these morphological digital elevation models provided by the USGS [6]. All imaging data observations (Fig. 5A). are maintained in an ArcMap GIS database. In addition to areal extent, we are able to infer the periodic Mineral composition was determined with reflectance spectra using existence of this glaciation (Fig. 5B) based the multiple outlet visible and near-infrared data from CRISM after being calibrated channels observed (Fig 2). using the volcano-scan technique [7]. Jezero Acknowledgements and References Crater

This work has benefited from reviews and discussions with Tim Goudge, Steven Ruff, Jim Head, and Bethany Ehlmann. All data and observations used in this study are publically available from the NASA PDS. Thank you to LaSPACE and NASA for providing funding via the GSRA grant and both MDAP and RAP via Suniti Karunatillake. Lastly, thanks to the Planetary Science Laboratory of LSU for the countless laughs, thoughtful discussions, and coffee runs. [1] Bramble, M. et al. (2017) Stratigraphy and Mineralogy of Northeast Syrtis Major. [2] Malin, M. C., et al. (2007) Context Camera Investigation on board the Mars Reconnaissance Orbiter. [3] McEwen, A. et al. (2007) Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (HiRISE). [4] Zuber, M.T., D.E. Smith, J.W. Head, D.O. Muhleman, S.C. Solomon, J.B. Garvin, J.B. Abshire, and J.L. Bufton (1992) Figure 4. Crater counting for two distinct volcanic units within our study area and corresponding plots The Mars Observer laser altimeter investigation. [5] Neukum, G., & Jaumann, R. (2004, August). HRSC: The high resolution stereo camera of Mars Express. In Mars Express: The Scientific Payload (Vol. 1240, pp. created with Craterstats 2.0. (Background CTX Mosaic with colored HRSC DEM overlay) 17-35). [6] Fergason, R.L, Hare, T.M., Laura, J., 2018, HRSC and MOLA Blended Digital Elevation Model at 200m v2, Astrogeology PDS Annex, U.S. Geological Survey, URL: http://bit.ly/HRSC_MOLA_Blend_v0 [7] Figure 2. Map of channel system on the edge of northeast Syrtis. Teal contour • This area (Fig. 4A) contains two distinct volcanic units McGuire, P. et al. (2009) An improvement to the volcano-scan algorithm for atmospheric correction of (-2450 m) indicates the highest level fully enclosed by the current basin CRISM and OMEGA spectral data. [8] Hartmann, W. K. (2005, April). Martian cratering 8: Isochron • The Hesperian Syrtis Major Volcanic unit that borders the basin (Fig. 4B) refinement and the chronology of Mars. [9] Quantin-Nataf, C. et al. (2018) Noachian to Amazonian topography, yet hydrologically accessible to the SE potential outlet channel. volcanic activity in NE Syrtis region. [10] Bramble, M. S., Mustard, J. F., & Salvatore, M. R. (2017). The Red contour (-2350 m) indicates minimum lake level required to activate the • One of Amazonian age within the basin (Fig. 4C) geological history of Northeast Syrtis Major, Mars. [11] Quinn, D.P. and B.L. Ehlmann (2018) Water-lain sulfates and episodic fluvial sedimentation and erosion spanning the middle Noachian to early eastern outlet channel. (Background: CTX mosaic with colored HRSC DEM • Age difference suggests protection of the basin through some mechanism Amazonian, Northeast Syrtis Major. [12] Soucek, O. et al., (2015) A 3 Ga old polythermal ice sheet in Isidis overlay) Planitia, Mars: Dynamics and thermal regime inferred from numerical modeling.