Simon N. StephensonUniversity of Oxford | OX
Simon N. Stephenson
Doctor of Philosophy
About
15
Publications
5,485
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261
Citations
Introduction
My interests are in understanding the evolution of mantle convection and its impact on surface dynamics such as sea level, stratigraphy and landscape evolution. I focus on constraining past and present dynamic topography with geological and geophysical observations.
Additional affiliations
July 2020 - September 2023
Position
- PostDoc Position
Description
- Using surface observations including geological, geophysical, and geochemical data as a tool for probing deep Earth processes including lithospheric evolution, mantle convection and subduction. Compiling and analysing large databases of constraints on crustal and lithospheric mantle structure to optimise mineral prospectivity mapping.
January 2019 - July 2020
Position
- PostDoc Position
Description
- Constraining global lithospheric and mantle structure through geological observations. Global compositional systematics of intraplate magmatism, age and evolution of the great escarpments.
October 2014 - present
Position
- Supervisor, Demonstrator
Description
- Geophysics core, masters project supervision, structural geology, tectonics, first year geooscience, Arran field course
Education
October 2010 - June 2014
Independent Researcher
Field of study
- Geology
Publications
Publications (15)
Continental topography is dominantly controlled by a combination of crustal thickness and density variations. Nevertheless, it is clear that some additional topographic component is supported by the buoyancy structure of the underlying lithospheric and convecting mantle. Isolating these secondary sources is not straightforward, but provides valuabl...
Large igneous provinces (LIPs) are formed by enormous (i.e., frequently >106 km3) but short-lived magmatic events that have profound effects upon global geodynamic, tectonic, and environmental processes. Lithospheric structure is known to modulate mantle melting, yet its evolution during and after such dramatic periods of magmatism is poorly constr...
Topography and bathymetry are principally supported by some combination of crustal and sub‐crustal density variations. However, dynamic topography is generated by vertical deflection of the Earth's surface as a result of mantle convection. Isolating and quantifying observable dynamic topography yields valuable information about mantle processes. He...
Successful inverse modeling of observed longitudinal river profiles suggests that fluvial landscapes are responsive to continent‐wide tectonic forcing. However, inversion algorithms make simplifying assumptions about landscape erodibility and drainage planform stability that require careful justification. For example, precipitation rate and drainag...
It has been proposed that Oligo-Miocene regional uplift of Madagascar was generated and is maintained by mantle dynamical processes. Expressions of regional uplift include flat-lying Upper Cretaceous-Paleogene marine limestones that crop out at elevations of hundreds of meters along the western seaboard and emergent Quaternary coral-rich terraces t...
The thermochemical structure of lithospheric and asthenospheric mantle exert primary controls on surface topography and volcanic activity. Volcanic rock compositions and mantle seismic velocities provide indirect observations of this structure. Here, we compile and analyze a global database of the distribution and composition of Neogene-Quaternary...
Alaska is made up of a mosaic of terranes that have enigmatic origins. Several plate restorations for the assembly of Alaska have been proposed, but their validity remains debated, partly due to the removal of vast volumes of oceanic plate material via subduction at the accretionary margins. The position, depth and volume of this subducted lithosph...
Earth's mantle undergoes convection on million-year timescales as heat is transferred from depth to the surface. Whilst this flow has long been linked to the large-scale horizontal forces that drive plate tectonics and supercontinent cycles, geologists are increasingly recognising the signature of convection through transient vertical motions in th...
The Marmara region in Turkey is an important geological setting, both from a tectonic and a seismic hazard/risk perspective. We present a new map of crustal thickness variation across this complex region to better understand the interplay of past and present tectonic processes that have formed present‐day structure. Maps of crustal thickness are cr...
Some portion of long-wavelength topography and bathymetry in the southwestern Indian Ocean is supported by convective processes within the Earth's mantle. Predictive models suggest that both southern Africa and the southwestern Indian Ocean are anomalously elevated by 0.5--1.5~km. In contrast, observed residual depth anomalies of the oceanic plate...
Geodynamic models of mantle convection predict that Mexico and western North America share a history of dynamic support. We calculate admittance between gravity and topography, which indicates that the elastic thickness of the plate in Mexico is 11 km and in western North America it is 12 km. Admittance at wavelengths > 500 km in these regions sugg...
Geodynamic models of mantle convection predict that Mexico and western North America share a history of dynamic support. We calculate admittance between gravity and topography, which indicates that the elastic thickness of the plate in Mexico is 11 km and in western North America it is 12 km. Admittance at wavelengths > 500 km in these regions sugg...
