Evaluation of Noachian-Hesperian Martian fluvial environments through Earth-based analogues
File(s)
Author(s)
Sangwan, Kartikeya Singh
Type
Thesis
Abstract
Fluvial landforms represent some of the best tools to reconstruct the surface processes on ancient Mars. However, in-situ observations of these landforms through rivers are severely limited. Thus, in this thesis, I examine fluvial landforms on Mars through Earth-based ancient and modern fluvial systems to reconstruct outcrop scale processes and the wider fluvial paleoenvironment. I first investigate the point bar deposits on the Jezero Western Delta Fan (JWF) and produce a fine-scale map of sedimentary package geometries of all major point bar exposures. This reveals their deposition in a vertically aggrading and regionally extensive, meander belt. I also show that the point bar deposits are thicker than previously reported and that the JWF’s stratigraphic units represent a continuum of fluvial processes. Additionally, based on consistent accretion direction towards the east, I propose a model for stronger paleoflow influence from the northern inlet during the early stages of JWF.
In the second project, I examine the cross-section of exhumed channel-belts in Caspe Formation Spain as an analogue for the fluvial ridges on Mars. I produce detailed architectural panels which reveal multi-storey reoccupationally-stacked channel sand bodies with saw-tooth structures on the edge formed by stacked channel wings and preserved floodplain fines between them. I also evaluate the usage of the term caprock for the fluvial ridges and show through examples from the Caspe Formation that the channel bodies may occupy the whole vertical height of the ridge and that sections of the channel-belt may remain unexhumed, all of which may make the usage of ridge dimensions for paleohydraulics erroneous. Utilising the observed distribution of channel bodies, I put forward hypothetical cross-sections for fluvial ridge structures on Mars.
In my third project, I map in planform the elements of the paleomeander belt of Karun channel, Iran, revealing accretion surfaces recording migration of meander bends and compensationally-stacked crevasse splay deposits. Finally, I discuss the formation mechanism for the stacked splays and through examples of candidate splays on Mars, I present a hypothesis and possible reasons for why channel-belt stratigraphy may record evidence of crevasse splays.
In the second project, I examine the cross-section of exhumed channel-belts in Caspe Formation Spain as an analogue for the fluvial ridges on Mars. I produce detailed architectural panels which reveal multi-storey reoccupationally-stacked channel sand bodies with saw-tooth structures on the edge formed by stacked channel wings and preserved floodplain fines between them. I also evaluate the usage of the term caprock for the fluvial ridges and show through examples from the Caspe Formation that the channel bodies may occupy the whole vertical height of the ridge and that sections of the channel-belt may remain unexhumed, all of which may make the usage of ridge dimensions for paleohydraulics erroneous. Utilising the observed distribution of channel bodies, I put forward hypothetical cross-sections for fluvial ridge structures on Mars.
In my third project, I map in planform the elements of the paleomeander belt of Karun channel, Iran, revealing accretion surfaces recording migration of meander bends and compensationally-stacked crevasse splay deposits. Finally, I discuss the formation mechanism for the stacked splays and through examples of candidate splays on Mars, I present a hypothesis and possible reasons for why channel-belt stratigraphy may record evidence of crevasse splays.
Version
Open Access
Date Issued
2023-02-14
Date Awarded
01/11/2023
Copyright Statement
Creative Commons Attribution NonCommercial Licence
License URL
Advisor
Gupta, Sanjeev
Davis, Joel M.
Sponsor
Imperial College London
International Association of Sedimentologists
Publisher Department
Earth Science & Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)