The Medusae Fossae Formation (MFF) is an enigmatic group of terrain features which dominate a quarter of equatorial Mars (extending - 5,500 km east-west). The MFF is characterised by a discontinuous, highly eroded appearance and is inferred to comprise fine grained and friable materials. This long-standing interpretation is based on observations of the prevalent aeolian erosional features (yardangs), This thesis aims to improve constraint of both the materials ori gins and the processes at work during and since their emplacement. The project uses a multi-scale, geomorphological approach, and uses the latest very high resolution (25 cm/pixel), and new medium resolution (6- 12 m/pixel), high spatial coverage data and attempts to use surface characteristics to constrain the origin of the formation. This thesis describes surveys of outlying MFF materials (to infer the palaeo-extent of the MFF), and a survey of textural characteristics of the outcrop materials and the quantitative analysis of yardangs. Following on from this, an evaluation of existing facies mapping (to improve understanding of the formation and evolution of the MFF) is discussed. A survey, and detailed study in one location, of sinuous ridge features (to evalu ate the role of volatiles and fluvial transport in the MFF) is also included. The key results include a larger pre-erosional spatial extent for the formation than previously thought, wherein outliers of the MFF are found on the Tharsis volcanic region and a hitherto unmapped uppermost "draping" unit is present. The existing definition of the geological members is found to require refinement. Furthermore, volatile content within the MFF is judged to be heterogeneous, and not limited to the oldest stratigraphic units. The evidence collated in this work is consistent with the hypothesis that the Medusae Fossae Formation is an ignimbrite deposit, comprised largely of dry (at least today), low density materials. but some MFF regions had much higher volatile content than others in the past.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:594183 |
| Date | January 2012 |
| Creators | Harrison, Samantha Kate |
| Publisher | Open University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
Page generated in 0.0023 seconds