Polyphase glaciation on Mars

Abstract

Mars today is a hostile environment. Surface water cannot persist for any meaningful duration across most of the planet. However, numerous glacial features are found in the mid-latitudes which indicate that this was not always the case. Reconstructing Mars’s glacial history informs understanding of its physical environment and past climate. The known distribution of viscous flow features (VFFs) containing water ice suggests that the mid-latitudes were glacierised during the Late Amazonian epoch (the last several hundred million years). However, e↵orts to constrain the formation age of VFFs have been fragmented and the known history of glaciation is uncertain. To explore the spatio-temporal history of ice and its past dynamics this thesis explores a series of VFFs and palaeo-VFFs using crater chronology, 2D flow modelling and the mapping of supra-VFF structures. Our dating reveals that the population of superposed VFFs implies spatially asynchronous glaciations and the occurrence of at least two cycles of glacial growth–recession before the period of reconstructible climatic forcing. Additionally, the dating of palaeo-VFFs reveals a complex pattern of regional ice retreat and suggests that ice masses are able to persist for ⇠1 billion years on Mars. Modelling of former ice surface elevation and the mapping of supraglacial structures reveals that VFFs have lost significant volumes of ice since their formation, and supraglacial structural patterns on VFFs are analogous to those observed upon glaciers on Earth. The thesis points to a complexity in the ice dynamics on Mars that has been ongoing for "1 billion years and may have ended as recently as ⇠2 million years ago.

Date of Award	2021
Original language	English
Awarding Institution	Aberystwyth University
Supervisor	Bryn Hubbard (Supervisor), Tom Holt (Supervisor) & Felix Ng (Supervisor)