THERMOCHRONOLOGY, TECTONICS AND BASIN FILL
How are sediments made, transported and distributed?
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Developing a fully quantitative understanding of the mechanisms and drivers that control the formation, transport and distribution of sediments, magam and the reactivity of fluids and heat within the Earth's crust remain key challenges within the solid Earth sciences. Making progress in these areas will enable real, practical solutions to several key societal challenges.
Improving resource security and diversity: Societal impact of our research will include de-risking resource and energy solutions (geothermal energy, water resources, sustainable mineral resource deposits, safe nuclear waste disposal, carbon capture and storage technologies), contribute to public policy and international development and train the next generation of world-class Earth Scientists.
THE UPS AND DOWNS OF THE OUTER HEBRIDES
The Outer Hebrides of NW Scotland are formed almost entirely of Archaean gneiss. A major ductile shear zone system called the Outer Hebrides Fault Zone (OHFZ) runs along the eastern margin of the Hebrides islands and brittle extensional re-activation along this zone occurred during the Permo-Triassic related to the the tectonic episode leading to the formation of the Hebrides and Minch basins which lie immediately to the east of the Hebrides. The basins are bounded to the west by the major, steeply east dipping Minch fault system, and it remains unclear whether this fault system was active through the Late Cretaceous and early Tertiary during renewed extension and the formation of the North Atlantic and the British Tertiary Igneous Province. In this work we aim to quantify the uplift and erosion history of the Outer Hebrides basement high using thermochronometry techniques and modelling and compare this with the record of offshore sediment accumulation within the marginal basins.
Thermochronology is the science of reconstructing the thermal evolution of the Earth. Combining accurate and computationally efficient algorithms to model the thermal diffusion and thermal annealing processes within individual grains (at a scale of micrometres) with algorithms that are able to exploit very large, spatially distributed data sets covering hundreds or even thousands of square kilometres is a major computational challenge. Our aim of this strand of our work is to develop and apply new computationally efficient algorithms and inversion techniques that will enable joint inversion of multi-method, widely distributed and very large thermochronology data sets to provide robust regional models of the thermal evolution of the Earth’s crust over geological time scales.
This work makes use of the high performance computing infrastructure provided by ARCHIE-WeSt.
ADVANCED DEVELOPMENT OF THE APATITE (U-TH)/HE THERMOCHRONOMETER
The accumulation of helium produced by radioactive decay of 238U, 235U and 232Th, and its progressive loss because of thermally activated diffusion, provides is the basis of the (U-Th)/He low temperature thermochronometry technique. Thermal history information is encoded in the dispersion of ages (or dates) measured for individual grains from the same rock sample. Interpreting the measured dispersion requires a quantitative understanding of the factors (e.g. grain size) and physical processes (such as diffusion) that determines each grain's age. A focus of our work is on developing robust modelling techniques that are able to extract reliable, quantitative thermal history information from the pattern of age dispersion in natural samples.
EXTREME HORST AND RIFT FLANK UPLIFT IN EAST AFRICA
We study rift flank and horst uplift in the East African Rift System using Thermochronology, Cosmogenic Nucliide dating, GPS measurements, Structural observations and stress inversion studies as well as numerical models. One example shows the popping up of the Rwenzori horst in the middle of the rift in Uganda up to 5000+m because it is composed of extremely hard northwards thrusted Amphibolites.
DOES MANTLE CONVECTION CONTROL CONTINENTAL TOPOGRAPHY?
Measuring surface elevation change of continents, especially in the past, is notoriously difficult. A focus of our work is to develop new approaches and methods that utilise thermochronometry data to constrain large scale, regional patterns of erosion which can help constrain patterns of surface elevation change at a temporal and spatial scale relevant to testing models of mantle dynamics.
Developing an understanding how different factors, such as tectonic processes, climate and sea level change may affect the nature and predictability of sedimentary basin fills. Understanding the variable, and also predictive nature of sedimentary fills, will enable a greater understanding of how to successfully explore and effectively produce key resources.
TECTONICS OF THE CONTINENTAL MARGINS OF NAMIBIA AND BRAZIL
As part of the DFG funded SPP SAMPLE we look at the tectonic evolution of the passive continental shelf of Namibia and Brazil. Exciting results published by Eric Salomon show how different both margins appear, with Namibia being a classic passive margin with reactivated basement structures and Brazil being a compressed margin that is not really passive, has no large scale basement reactivation and is internally deformed because South America is rotating.