Mon 24 Mar 11:30: Interaction of Mechanical Ventilation and Natural Convection
Abstract not available
- Speaker: Dan Toy, IEEF
- Monday 24 March 2025, 11:30-12:30
- Venue: Open Plan Area, Institute for Energy and Environmental Flows, Madingley Rise CB3 0EZ.
- Series: Institute for Energy and Environmental Flows (IEEF); organiser: Catherine Pearson.
Mon 17 Mar 18:00: Influence of metamorphism and partial melting on creating LCT-enriched granitic melts
Decarbonising our energy and transport systems is a major challenge for addressing the climate crisis. This will require a whole range of different raw materials including critical elements associated with LCT granites and pegmatites (Linnen et al., 2012). However, at the moment we are lacking a solid understanding of how and where LCT melts form which also means reliable geological exploration models don’t exist.
Geochemical characterisation of LCT granites and pegmatites shows (re-)melting of continental crust as the source (Černý et al., 2012). Which means metamorphism and partial melting are an essential process in the formation of LCT melts. The classical model assumed the onset of muscovite melting to be the key process. As micas are known hosts of critical elements (e.g., Li, Be, V, Rb, Cs, Sn, Ta, W) and would release their trace elements into a relatively small volume of melt, which creates enriched melts. These melts would be further enriched during fractional crystallisation finally creating element concentrations of economic interest. Contrary to that theory a study on whole rock compositions (Wolf et al., 2018) and of metamorphic micas from greenschist to granulite facies conditions (Kunz et al., 2022) have shown that biotite is the major host of elements associated with LCT melts. This raises the question if (1) biotite melting might be the essential process for producing LCT enrichment and (2) under which partial melting conditions this would create the highest critical element enrichment.
Over the last couple of years, a number of studies have started to address these questions ranging from natural observations to modelling and partial melting experiments. Some of the key questions and challenges at the moment are: (1) is an enriched sedimentary source needed?; (2) what is the importance of the melting conditions/reaction for enrichment?; (3) overcoming limitations of natural and experimental research approaches and (4) developing robust input parameters for partial melting modelling.
- Speaker: Dr Barbara Kunz - The Open University
- Monday 17 March 2025, 18:00-19:00
- Venue: Harker 1 lecture room, Department of Earth Sciences, Downing Site.
- Series: Sedgwick Club talks; organiser: Susannah Scott.
Mon 10 Mar 18:00: Critical Transitions: Responsible Resource Management in a Complex World
Critical Materials are a longstanding concept, with the United States referring to “Strategic Minerals” in 1917 as those for which domestic supplies were inadequate in quantity, quality, or both. In recent decades, awareness of Critical Materials has increased – from the “Rare Earth Crisis” from 2010 to 2015, and more from the vulnerabilities of global supply chains exposed during the COVID -19 pandemic and conflict in Ukraine. Not only are these Critical Materials important for general functioning and security of nations; there are additional pressures being placed particularly on metals value chains from the need for metals for energy transition and sustainable development ambitions.
Circularity strategies have been advocated as a mechanism to enhance critical raw materials (CRM) security in the UK and Europe. Especially in the context of reducing import reliance and thus decreasing supply risk by having domestic/localised cycling of key metals and materials. Circular Economy (CE) principles-based systems may initially appear to contradict continuation of a primary raw materials extractive sector. However, there is a growing body of research examining the development of CE practices in the mining industry, in order to increase resource efficiency by understanding better potential co- and by-products, more efficient extraction and processing, and use/ re-use of waste products.
This talk explores the application of circular economy principles to the mining sector, with a focus on critical metals projects in Cornwall, and more broadly how these principles interface with geology and geoscience’s place in developing responsible resource management systems.
- Speaker: Dr Eva Marquis - University of Exeter
- Monday 10 March 2025, 18:00-19:00
- Venue: Harker 1 lecture room, Department of Earth Sciences, Downing Site.
- Series: Sedgwick Club talks; organiser: ss2849.
Wed 12 Mar 14:00: Unravelling magma-water interaction in an oceanic core complex with full-waveform imaging and numerical modelling
3D full waveform inversion (FWI) has been applied to the seismic refraction data of the MARINER (Mid-Atlantic Ridge INtegrated Experiment at Rainbow) experiment to create a robust high-resolution model of the seismic velocity structure of the Rainbow massif. The Rainbow massif is an oceanic core complex located on a non-transform discontinuity (NTD) in a magma-starved region of the mid-Atlantic Ridge at 36ºN. Despite the low magmatic input, the core complex hosts a high-temperature hydrothermal vent field (>340°C) that requires a long-lived magmatic heat source. The FWI results show that deep within the massif, ∼3-8 km below the seafloor, lies a low-velocity body that represents a partially molten sill complex. The sill complex extends north to the AMAR Minor N segment suggesting an increased magmatic input into this segment, forcing the NTD to migrate southwards. Extensive magmatic intrusion into the core complex was likely responsible for termination of slip on the detachment fault. We model hydrothermal fluid flow inside the Rainbow massif using the Imperial College Finite Element Reservoir Simulator (IC-FERST). The model geometry, thermal properties, flow properties and boundary conditions are informed by the seismic constraints. We show that the high temperatures within the core of the Rainbow massif prevent serpentinization from taking place and govern the location of the serpentinization front.
- Speaker: Michele Paulatto, Imperial College London
- Wednesday 12 March 2025, 14:00-15:00
- Venue: Wolfson Lecture Theatre.
- Series: Bullard Laboratories Wednesday Seminars; organiser: Tom Merry.
Fri 07 Mar 16:00: Channels or waves: controls on melt migration through the upper mantle
Abstract not available
- Speaker: Min Huang
- Friday 07 March 2025, 16:00-17:00
- Venue: Tea Room, Old House.
- Series: Bullard Laboratories Tea Time Talks; organiser: David Al-Attar.
Wed 05 Mar 14:00: 3D tomographic constraints on upper-plate elastic structure and inter-plate geometry offshore the Ecuadorian-Colombian margin
In subduction zones, upper-plate elastic rock properties play a major role in controlling megathrust fault dynamics (Sallarès & Ranero 2019; Prada et al., 2021; Ulrich et al., 2022). The variations of these properties in the downdip direction are influenced by increasing confining pressure with depth, forming a global depth-dependent pattern (Sallarès & Ranero 2019). However, the understanding of how these properties vary along-strike, especially above the interplate, where elastic energy is stored during interseismic cycle, remains unclear. Here we present 3D tomographic constraints on the velocity structure of the upper plate as well as the inter-plate geometry offshore the Ecuadorian-Colombian margin. The study area has been the locus of large megathrust tsunamigenic earthquakes, including the seventh largest in history (1906 Mw~8.8 Esmeraldas), but elastic properties above the megathrust are not mapped hitherto. Here we use 3D wide-angle seismic (WAS) dataset acquired in 2005 during the ESMERALDAS survey and multichannel seismic (MCS) lines to integrate tectonic information to our tomographic results. WAS data were acquired with 26 ocean bottom seismometers from which we picked travel times of P-waves refracted through the upper and lower plates, as well as P-wave reflections at the interplate. We invert travel times with a 3D joint reflection and refraction travel time method (Melendez et al., 2015) following a Monte Carlo approach to provide uncertainties on model parameters.The resulting model shows the 3D P-wave velocity (Vp) structure of the upper and lower plates as well as the geometry of the interplate reflector. Additional elastic parameters such as rigidity (i.e., shear modulus) were derived using empirical relationships between Vp, Vs, and density. Downdip variations in rigidity align with the inferred global trend. However, rather than being laterally consistent, elastic properties exhibit remarkable variations along-strike within the rupture area of the largest recorded earthquakes. MCS sections in the study area depict a complex interaction between crustal-scale faults. This interaction has been proposed to control the seismogenic behavior of the subduction zone in this region, promoting the occurrence of confined ruptures (Collot et al., 2004). A comparison between MCS reflection lines and tomographic results reveals a correlation between localized low-rigidity upper-plate regions and the interaction of such crustal-scale faulting. The presence of low rigidity areas above the interplate may enhance coseismic slip, while locally damaged regions in the upper-plate may favour inelastic deformation during coseismic events, promoting localised seafloor uplift. In contrast to downdip elastic rock variations above the upper-plate, our results indicate that along-strike variations are dependent on the interaction of crustal-scale structures and, consequently, on local geology.
- Speaker: Manel Prada -- Institute of Marine Sciences, Spanish National Research Council (CSIC)
- Wednesday 05 March 2025, 14:00-15:00
- Venue: Wolfson Lecture Theatre.
- Series: Bullard Laboratories Wednesday Seminars; organiser: ChuanChuan Lu.