Science goals and objectives: terraced fan deposits are unique geomorphic indicators of point source sedimentation on mars. Their stair-step topography differs from classic profiles of alluvial fans…

Tennessee Technological University, a public university in Cookeville, Tennessee, has been awarded a $132,046.78 grant for research from the National Aeronautics and Space Administration (NASA) Shared Services Center. The grant is to conduct a study on terraced fan deposits on Mars, which are unique geomorphic indicators of sedimentation. The objective is to integrate multiple datasets to map and investigate the stratigraphy of two specific terraced fan deposits on Mars, the Subur Vallis Fan and Aeolis Mensae Fan. This research aims to test the hypothesis that fluvio-deltaic processes were responsible for the formation of these terraced fans during the Late Noachian and Early Hesperian periods on Mars. The award does not have a set-aside designation and is scheduled for completion on December 21, 2022.

Science goals and objectives: terraced fan deposits are unique geomorphic indicators of point source sedimentation on mars. Their stair-step topography differs from classic profiles of alluvial fans or gilbert-type deltas, and the sediment gravity flow processes responsible for terrace development are unclear. Proposed formative mechanisms include pulsed sedimentation through time, deposition into a standing body of water and/or reworking by wind-driven wave activity. Until recently, features that would be indicative of these processes boulders, incised distributary channels, narrow levees, barforms were too small to resolve using photogrammetric methods. However, we now have the capability of investigating such surface textures using digital elevation models and high-resolution stereo-pair imagery returned from the mars reconnaissance orbiter (HIRISE). The primary objective of this proposal is to integrate multiple datasets to conduct detailed geologic mapping of two terraced fan deposits, the subur vallis fan (11.73 N, 52.93 W) and aeolis mensae fan (6.53 S, 141.14 E). A second objective is to investigate the stratigraphy of each fan to identify vertical and lateral variations in terrace lithologies, a possible indicator of: (a) changing point source and flow/phase conditions through time, or (B) geochemical evolution of a standing fluid. In terms of scientific merit, the proposed work will test the hypothesis that fluvio-deltaic processes were responsible for terraced fan formation during the late noachian and early hesperian. A global survey of more than a dozen terraced fans developed during this time period show that their channel systems breach both chasma and crater walls, which may imply that standing bodies of water were not uncommon. Methods: to accomplish the objectives, this study will integrate multiple datasets at nested resolutions. 1. Task I will focus on creating digital elevation models (DEMS) of terraced fan deposits in subur vallis and aeolis mensae. CTX images, HIRISE stereo-pairs and mola topographic tie-points are available for both fans and cover incised feeder channels, steep walls of the crater/chasma and well-developed terrace steps. Structural deformation in these locations is limited compared to other fan deposits. 2. Task II will use multispectral data from themis and hyperspectral data from crism to investigate: bedrock exposure, dust accumulation, mineral distribution, and presence/absence of hydrated mineral deposits on terraces. The results from tasks I and II will allow characterization of vertical and lateral variations and construction of a stratigraphic framework for each fan. Textural geomorphic indicators of sediment gravity flow processes and similarities between the two locations will inform a model of terraced fan formation. 3. Task III, conducted concurrently with the previous two tasks, will synthesize results to generate a geologic map of a martian terraced fan (1:18000 scale). Map units and relative ages will be based on cross-cutting relationships and detailed stratigraphic sections. The orientation of bedding and stratal packages will be estimated using strike and DIP measurements from DEMS. This type of very detailed mapping has been previously limited to a few structurally complex areas and sites calibrated with lander data.