Earth is a dynamic planet, for the simple reason that it is still cooling down from the heat of accretion and subsequent decay of radioactive elements. The main mechanism by which it loses heat is plate tectonics, a theory that has been widely accepted since the 1970s. The Earth is formed of a dense metallic core surrounded by a partially molten silicate mantle which itself is capped by a buoyant crust, either continental or oceanic. We live on the continental crust which largely exists above sea level. The ocean crust forms the floors of oceans and is only rarely exposed. The ocean crust forms by mantle melting at mid ocean ridges, such as the mid Atlantic ridge upon which sits the volcanic island of Iceland. New crust is constantly formed, forcing the older crust to spread outwards and oceans to grow larger. As the ocean crust spreads away from the ridge, it cools and becomes denser. Eventually it interacts with a continent, made of less dense material. The ocean crust is driven beneath the continent back into the mantle, a process known as subduction. Volcanoes form along the continental margin above the subduction zone and at least some of this activity results in addition of new continental crust. This may have been the main process responsible for initial formation and subsequent evolution of our continents. It can be observed now around the margin of the Pacific Ocean, where widespread volcanism is known as the "Ring of Fire". However, not all oceans can continue to grow! The Atlantic Ocean has stopped getting bigger as a response to the continued growth of the Pacific. Eventually, an ocean will close completely and the surrounding continents will collide, resulting in a linear mountain chain. A good example is the Himalaya, where India has collided with Asia. This whole process known as plate tectonics has a profound affect on our planet, providing us with land on which to live, seas in which to fish, freshwater to drink and our complex weather patterns. It is also a regulator of our climate since weathering of continental rocks results in drawdown of CO2 to the deep sea where it is stored. Understanding plate tectonics is central to Earth and Environmental Scientists. There are still important details that we know little about, such as how and when it began. This proposal seeks to investigate this by a novel study of critical rocks that characterise plate tectonics, in particular those that result from subduction. When ocean crust is subducted, increasing pressure and temperature change it into denser rock. As the Earth has evolved, the exact pressure and temperature conditions of this "metamorphism" have also changed. We propose to study this by using minerals that form within ocean crust during subduction. The rocks themselves are often destroyed by erosion, but tiny crystals of a robust mineral called rutile (titanium dioxide) can survive to be found in sediments derived from them. By dating these and using their chemical composition as a fingerprint, we can work out the pressure and temperature within the eroded subduction zone. Similarly, the volcanic rocks that form during subduction have changed through time. These are also often destroyed by erosion so that the exposed record may not be representative. Another robust mineral known as zircon (zirconium silicate) often survives the weathering and ends up alongside rutile in the younger sediments. Using similar methods with zircon we can also investigate changing styles of magmatism throughout Earth's history. . Currently the magmatic record implies that modern subduction began around 2500 million years ago, yet the metamorphic record implies a later start of around 700 million years ago. Our novel approach will test this. We will be able to say whether the younger date is correct and the older marks a different kind of plate tectonics, or whether the older date does indeed represent the onset of modern plate tectonics, and the exposed rock record is biased.

Leeds dynamo simulations for the analysis of rapid changes in the geomagnetic field. In each folder, the following file can be found: - state.cdf.in - the configuration file used as an intial condition to launch each simulation Some folders have multiple state.cdf.in files for each run of the same simulation, if only part of the data was needed to be reproduced. Additionally, most folders contain: - LSD.info/main.info - Contains details of the parameters for each simulation, which can be used for reference when recompiling the code - LSD.out/main.out - the exectuable used to submit a simulation to a hpc; for the code to be reran, this would have to be recompiled (see Leeds_Dynamo_Code_Manual.pdf) - run.bolt/run.sh - the scripts used to submit a simulation to the leeds hpc (.sh file) or archer2 (.bolt file) Details of how to run the Leeds dynamo code can be found in Leeds_Dynamo_Code_Manual.pdf, which contains a more in-depth description of input parameters, boundary conditions, output data etc. The parameters for each simulation can also be found in the spreadsheet 'SimulationsLog'. More details about the difference between thermally-driven and thermochemically-driven cases can be found in Nakagawa and Davies, 2022. Note all simulations have Prandtl number Pr=1. We have ran a series of simulations to help us elucidate the origin of rapid changes in the Earth's magnetic field. Observational models of the magnetic field have found changes in field intensity and direction that significantly faster than the values and averages for the modern field. The simulations provided here have been analysed to find the features that best reproduce dynamical and morphological agreement with the observed field, as well as to find rapid changes in the simulated field that are in agreement with that of the observed field (see Nakagawa and Davies 2022). Simulations have been ran using the Leeds Dynamo Code, and the configuration files provided here allow users to reproduce and interpret the data used for analysis.

The dataset contains the outputs from 3D spherical incompressible mantle convection models. Included outputs, such as visualisation files (to use with open-source software ParaView), allow to analyse the links between the thermal evolution of the mantle and the preservation of geochemical heterogeneity. The data is linked to the manuscript titled "Geodynamic Controls on Mantle Differentiation and Preservation of Long-Term Geochemical Heterogeneity: Focus on the Primitive Undegassed Mantle”. The dataset gathers outputs to produce the figures of the article and post-processing scripts. It also includes the necessary input files and executables needed to reproduce the geodynamic simulations. More details in the README.md file.

Included video files are visualisations of the temporal evolution of the following 3D spherical mantle convection models: 05_depltd, 03_depltd, 07_depltd, 1_22_visc, 3_22_visc, no_lid_visc, 10_lid_visc, lT_init, hT_init Each video file shows the temporal evolution of thermal anomalies (compared to layer average) and of Primitive Particle Concentration (PPC, i.e. the fraction of primitive undegassed particles to the total number of paticles owned by each grid node). Video files can be opened using open-source multimedia softwares such as VLC or QuickTime Player. These files are supplementary video files for manuscript titled "Geodynamic Controls on Mantle Differentiation and Preservation of Long-Term Geochemical Heterogeneity: Focus on the Primitive Undegassed Mantle”.

Locations of samples collected to constrain the recent activity on normal faults across Nevada. The geological samples will be used to measure the amount of exhumation that different normal faults of the Basin and Range experienced over the last 5 million years. The samples have been collected from granitic rocks that are expected to yield apatite crystals. (Uranium-Thorium)/Helium thermochronometry will be conducted on these samples to determine the cooling history of rocks from temperatures of approximately 70 degrees celsius. The samples are collected across Nevada at locations close to the fault to determine the most recent stages of exhumation. The ranges sampled are the Wassuk Range, White Range, Toiyabe Range, South Egan Range, Schell Range, Wheeler Range, House Range, Wasatch, Deep Greek, Ruby Range, Cortez Range, Humbolt Range, Dixie Valley, and Carson Range. Samples weigh approximately 2kg each. This sample coverage will constrain extension rates across the Basin and Range which is of interest to geologists, geodynamicists, and researchers interested in fault hazard.

A complete picture of the processes occurring on seismically active faults is the essential prerequisite for the reliable assessment and mitigation of earthquake hazards. But earthquake parameters vary greatly over the fault in large earthquakes. For example, earthquake fault slip can range from 1-15 metres on different portions of the fault for any earthquake. Further slow slip has also been observed after a recent earthquake. In addition, earthquake damage depends directly on the speed at which the Earth's crust fractures. Our earlier studies showed that it is possible for this rupture velocity to be very high on some portions of the fault. Thus, sites close to regions of higher rupture velocity would be damaged more than other regions. Advance knowledge of such sites, based on earthquakes that have already occurred, is invaluable for making decisions on siting of critical structures (for example, dams, bridges, power plants, etc.). This proposal aims to quantify the distribution of slip, rupture speed, stress drops, and other fundamental source characteristics over the fault for several recent large earthquakes, by analysing seismograms. The results will also be used to increase our understanding of active tectonic areas. The relevant equations will be solved using a massively parallel computer cluster. The recent occurrence of several large earthquakes makes this investigation timely.

This proposal seeks to test the hypothesis that a mantle hotspot was responsible for generating boninite magmas in the Izu - Bonin - Mariana (IBM) arc during the middle Eocene. Reconstruction of the plate configuration at that time places the nascent IBM arc close to the location of the present Manus Basin, where a high 3He/4He hotspot has been identified through helium isotope data and tomographic imaging. This project will deliver: 3He/4He data for middle Eocene boninites to resolve the hotspot-present or hotspot-absent models for initiation of the IBM arc. Pb and O isotope ratios and U and Th concentration data to aid in constraining subduction and crustal contamination in the petrogenesis of these rocks. A framework for investigating Archean tectonics and volcanic massive sulphide deposits.

This dataset contains the locations and other pertinent information for 122 well-constrained seismic events that occurred on or near Corbetti between February 2016 and September 2017. These locations were derived from data collected on 37 broadband seismometers deployed as part of the RiftVolc project. The data were originally published in Lavayssière, A., et al. "Local seismicity near the actively deforming Corbetti volcano in the Main Ethiopian Rift." Journal of Volcanology and Geothermal Research (2019). https://doi.org/10.1016/j.jvolgeores.2019.06.008

Olivine, the major component of the Earth's upper mantle, is known to contain water in the form of H defects. These defects have a significant effect on the physical and chemical properties of minerals. If we are to correctly interpret seismic data from the upper mantle, and to constrain models of its petrologic and geochemical evolution, then we must have information on the energies and mechanisms of water solubility in olivine, and its effects on physical properties. The aim of this project is to use computer simulation methods to predict the nature of H defects in olivine, their mobility, and their effects on elasticity as a function of pressure, and to use this information to better constrain models of dynamic behaviour of the Earth's upper mantle.

Since 20 September, 2005, an ~120 km-long segment of the Red Sea rift system in Ethiopia has been rocked by 31 earthquakes detected on seismometers worldwide. Ashes emanating from long, open fissures at the surface have blanketed a much wider area, displacing ~50,000 people and their livestock. Colleagues from Addis Ababa University report new fault scarps, and new displacements along existing fault scarps; these faults provide direct measures of rates of crustal deformation that can only be inferred from routine monitoring. The active rupture zone is much larger than has been associated with other historic sequences in the Afar depression, and other continental rift zones worldwide, suggesting this linked tectonic-volcanic crisis is a major event. Thus, the Boina seismo-volcanic crisis provides a superb opportunity to record directly the processes of continental breakup leading to the formation of a new ocean basin. Routine seismic, volcanic, and geodetic monitoring provides information on the time-averaged deformation, but misses the sometimes catastrophic discrete events that achieve the tectonic processes. This proposal aims to: 1) establish a seismic monitoring network to measure aftershock sequences and lava movement within the plate; 2) investigate reports of new eruptions and measure gas emissions from vents along the length of the rupturing segment and compare them with earlier baseline measurements from Afar; and 3) use space-based radar images acquired prior to, during, and after the crisis to measure the magnitude and extent of deformation across the region. Simple elastic modelling of seismic and radar interferometry results will allow us to estimate the proportion of tectonic vs magmatic deformation associated with continental rupture. Additionally, our measurements will provide a firm basis for hazard mitigation for the Ethiopian government coping with this catastrophe, supplementing the sparse infrastructure established by our Ethiopian colleagues.