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Title: Uplift and erosion histories of ancient and modern landscapes : examples from the North Sea, Iceland, and Mars
Author: Stucky de Quay, Gaia
ISNI:       0000 0004 7969 872X
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2019
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Ancient and modern landscapes contain records of vertical motions which can be used to probe histories of sub-surface processes. In this work I examine how rates of landscape evolution and styles of erosion can be determined using biostratigraphy and seismic data, cosmogenic dating techniques, and cratering on extra-terrestrial surfaces. I explore three examples, a buried landscape in the North Sea, a modern-day Icelandic river, and finally an example from Mars. First, I examine sedimentary basins fringing the North Atlantic Ocean, which contain excellent evidence that the continental shelf experienced episodic sub- aerial exposure. Stratigraphy, well logs, cores, and seismic data are used to reconstruct a 55 Ma terrestrial landscape buried 1.5 km beneath the North Sea. The best-fitting uplift rate history from extracted longitudinal profiles is staged, similar to that of a buried landscape in the nearby Faeroe-Shetland. These vertical motions are consistent with response to pulses from the incipient Icelandic plume. Secondly, I determine the erosional history of the modern Icelandic landscape. Today, the Icelandic plume is located beneath Iceland. Longitudinal river profiles across Iceland contain broad knickzones such as the Jökulsárgljúfur. High-resolution photogrammetry and 3He exposure ages of terraces indicate retreat rates of ∼ 70 cm yr−1 in the Holocene. Calibrated drainage inversion indicates that rifting, dynamic support, and isostatic ad- justment resulted in tens to hundreds of meters of modern uplift, and that progressive fluvial processes set the pace for erosion in volcanic, postglacial landscapes. Finally, preserved drainage patterns on Martian craters contain longitudinal profiles similar to fluvial terrestrial craters. However, an under- standing of the effects of g, climatic and tectonic forcing, and valley formation timescales are lacking. A prominent example of drainage is Warrego Valles, a high-density dendritic system in southern Thaumasia. Spectral analyses indicate its power is greatest at > 10 km wavelengths, and river inversions suggest it was uplifted by the Tharsis Bulge. The results of this work addresses key problems concerning longevity of topography and the roles of denudation, tectonics, and sub-surface processes. Uplift and erosion histories of the North Sea, Iceland, and Mars provide crucial constraints on dynamic support, mantle viscosity and temperature, closure of ocean gateways, rifting and magmatism, and surface processes on solar system bodies.
Supervisor: Roberts, Gareth ; Jackson, Chris Sponsor: Natural Environment Research Council ; DTP
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral