2019 AAPG Annual Convention and Exhibition:

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Using Earth’s Sedimentary Record to Inform Studies of Delta Channel Deposits on Mars

Abstract

Decades of planetary exploration have revealed an abundance of geomorphic evidence for ancient (>3.5 Ga) fluvial activity on the surface of Mars; however, only in the past ~10-15 years have orbital remote sensing data sets existed with the necessary resolution to study the details of martian sedimentary deposits. These data, combined with rovers exploring sedimentary outcrop in situ, have revealed an extensive and fascinating sedimentary rock record on Mars. Such studies also provide an exciting opportunity to apply lessons learned from studying the terrestrial rock record to another world, and to test the controls of planetary-scale boundary conditions (e.g., gravity) on sedimentary processes and their deposits.

Here we will present a study of the large-scale sedimentary structures of a delta deposit within the Jezero crater paleolake basin, with the goal of reconstructing its evolution and shoreline position. We used high-resolution orbital images and stereo-derived digital elevation models (DEMs) to map two primary classes of exposed channel stratigraphy. The stratigraphically lowest channel stratigraphy is eroded point bar strata deposited on the inner banks of a meandering river channel. Above the point bar strata are relatively straight, stacked channel-filling deposits preserved as inverted topography. We used novel analysis techniques to quantify the geometries of the channel deposits in order to constrain the paleohydrology of the flows associated with their formation. Finally, we integrate our results to develop a self-consistent stratigraphic framework for this deposit, and reconstruct a scenario for the evolution of the Jezero crater delta and paleolake in which it formed.

The Jezero crater delta is a representative example of ancient fluvial stratigraphy on Mars, and so has the potential to more broadly inform our understanding of martian fluvial systems. In the context of the research symposium, our study is meant to stimulate discussion of: (1) how sedimentary geoscientists can apply their knowledge to addressing inter-disciplinary problems, such as in the broad field of planetary science; and (2) how studies of the sedimentary rock record on different planetary bodies can be used to more broadly inform our understanding of sedimentary systems on Earth.