Imperial College London

MrMatthewMorris

Faculty of EngineeringDepartment of Earth Science & Engineering

Research Postgraduate
 
 
 
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Contact

 

matthew.morris15

 
 
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Location

 

2.49ARoyal School of MinesSouth Kensington Campus

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Summary

 

Publications

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2 results found

Morris M, Lipp A, Roberts G, 2023, Towards inverse modelling of landscapes using the Wasserstein distance, Geophysical Research Letters, Vol: 50, Pages: 1-8, ISSN: 0094-8276

Extricating histories of uplift and erosion from landscapes is crucial for many branches of the Earth sciences. An objective way to calculate such histories is to identify calibrated models that minimize misfit between observations (e.g., topography) and predictions (e.g., synthetic landscapes). In the presence of natural or computational noise, widely used Euclidean measures of similarity can have complicated objective functions, obscuring the search for optimal models. Instead, we introduce the Wasserstein distance as a means to measure misfit between observed and theoretical landscapes. Our results come in two parts. First, we show that this approach can generate much smoother objective functions than Euclidean measures, simplifying the search for optimal models. Second, we show how locations and amplitudes of uplift can be accurately recovered from synthetic landscapes even when seeded with different noisy initial conditions. We suggest that this approach holds promise for inverting real landscapes for their histories.

Journal article

Morris M, Fernandes VM, Roberts GG, 2020, Extricating dynamic topography from subsidence patterns: Examples from Eastern North America's passive margin, Earth and Planetary Science Letters, Vol: 530, Pages: 1-13, ISSN: 0012-821X

Global sea-level (eustatic) histories generated by backstripping stratigraphy are predicated upon the lithosphere having a well understood tectonic history. However, sub-plate processes play a role in governing lithospheric vertical motions with timescales and amplitudes akin to eustasy, which are difficult to predict. We examine how stratigraphic and geophysical observations combined with simple isostatic models can be used to disentangle histories of sub-plate support and eustasy. We focus on the passive margin of Eastern North America, where a generally accepted history of eustasy has been estimated. Negative long wavelength free-air gravity anomalies, residual ocean-age depth estimates, fast upper mantle shear wave velocities, and geodynamic models suggest that Cenozoic evolution of this passive margin has been influenced by upper mantle drawdown. We build on existing analyses to backstrip sixteen wells, which, combined with seismic data, constrain timing and extent of Cenozoic subsidence. Results indicate up to ∼1000 m of water-loaded subsidence between ∼20–0 Ma centered on the Baltimore Canyon Trough. Seismic data from the trough shows Neogene aggrading clinoforms. There is little evidence for faulting or stratigraphic growth, which indicates that Neogene lithospheric strain rates were low. Amplitude and spatial extent of Neogene subsidence are difficult to explain by glacio-eustasy or glacio-isostatic adjustment. Instead, sub-plate support calculated from conversion of shear wave velocities to temperature and isostatic calculations indicate that upper mantle drawdown was responsible for subsidence of the margin. Because mantle convection is vigorous such observations are expected throughout the stratigraphic archive.

Journal article

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