Preprints
Filtering by Subject: Earth Sciences
Dissolution precipitation creep as a process for the strain localisation in mafic rocks
Published: 2021-08-17
Subjects: Earth Sciences, Geochemistry, Tectonics and Structure
Unaltered mafic rocks consist of mechanically strong minerals (e.g. pyroxene, plagioclase and garnet) that can be deformed by crystal plastic mechanisms only at high temperatures (>800°C). Yet, many mafic rocks do show extensive deformation by non-brittle mechanisms when they have been subjected to lower temperature conditions. In such cases, the deformation typically is assisted by mineral [...]
Post-LGM glacial retreat and Early Holocene monsoon intensification drives aggradation in the interiors of the Kashmir Himalaya
Published: 2021-08-15
Subjects: Earth Sciences
Understanding the response of glaciated catchments to climate change is crucial for assessing sediment transport from the high-elevation, semi-arid sectors in the Himalaya. The fluvioglacial sediments stored in the semi-arid Padder valley in the Kashmir Himalaya record valley aggradation during ~20 -10 ka. We relate the initial stage of valley aggradation to increased sediment supply from the [...]
The role of sediment subduction and buoyancy on subduction dynamics and geometry
Published: 2021-08-14
Subjects: Earth Sciences, Physical Sciences and Mathematics
Subducted sediments are thought to lubricate the subduction interface and promote faster plate speeds. However, global observations are not clear-cut on the relationship between the amount of sediments and plate motion. Sediments are also thought to influence slab dip, but variations in subduction geometry depend on multiple factors. Here we use 2D thermomechanical models to explore how sediments [...]
The role of surface processes in basin inversion and breakup unconformity
Published: 2021-08-03
Subjects: Earth Sciences, Geology, Stratigraphy, Tectonics and Structure
At divergent plate boundaries, extensional tectonics lead to subsidence, continental rifting and the formation of continental margins. Yet, within this extensional context, transient compressional structures (stress inversion) and phases of uplift (depth inversion) are frequently recorded with no corresponding change in plate motion. Changes in gravitational potential energy during the rifting [...]
Salt welding during canopy advance and shortening in the Green Canyon Area, northern Gulf of Mexico
Published: 2021-07-30
Subjects: Earth Sciences, Geology, Other Earth Sciences, Tectonics and Structure
Welds form due to tectonically-induced thinning and/or dissolution of salt, with their composition and completeness thought to at least partly reflect their structural position within the salt-tectonic system. Despite their importance as seals or migration pathways for accumulations of hydrocarbons and CO2, we have relatively few published examples of drilled subsurface welds; such examples would [...]
Characterizing and Correcting Phase Biases in Short-Term, Multilooked Interferograms
Published: 2021-07-30
Subjects: Earth Sciences, Geology
Interferometric Synthetic Aperture Radar (InSAR) is widely used to measure deformation of the Earth’s surface over large areas and long time periods. A common strategy to overcome coherence loss in long-term interferograms is to use multiple multilooked shorter interferograms, which can cover the same time period but maintain coherence. However, it has recently been shown that using this strategy [...]
Strengths and limitations of in situ U-Pb titanite petrochronology in polymetamorphic rocks: An example from western Maine, USA.
Published: 2021-07-29
Subjects: Earth Sciences, Geochemistry, Geology, Other Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Titanite is a potentially powerful U-Pb petrochronometer that may record metamorphism, metasomatism, and deformation. Titanite may also incorporate significant inherited Pb, the correction for which may introduce inaccuracies and result in geologically ambiguous U-Pb dates. Here we present laser ablation inductively coupled mass spectrometry (LA-ICP-MS)-derived titanite U-Pb dates and trace [...]
The Virtual Geoscience Revolution: From William Smith to Virtual Outcrop
Published: 2021-07-29
Subjects: Earth Sciences
In 1799 an English surveyor named William Smith published the World’s first geological map. This map, which covers the whole of England and Wales, fundamentally changed the way that geologists visualised the subsurface (Winchester, 2001). For the next 200 years, field geologists across the World worked in much the same way as Smith had done, tracing geological boundaries on the ground and using [...]
Kinking facilitates grain nucleation and modifies crystallographic preferred orientations during high-stress ice deformation
Published: 2021-07-28
Subjects: Earth Sciences, Physical Sciences and Mathematics, Planetary Sciences
Kinking can accommodate significant amounts of strain during crystal plastic deformation under relatively large stresses and may influence the mechanical properties of cold planetary cryosphere. To better understand the origins, mechanisms, and microstructural effects of kinking, we present detailed microstructural analyses of coarse-grained ice (~1300 µm) deformed under uniaxial compression at [...]
The impact of spatially varying ice sheet basal conditions on sliding at glacial time scales
Published: 2021-07-28
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
Spatially variable basal conditions are thought to govern how ice sheets behave at glacial time scales (>1000 years) and responsible for changes in dynamics between the core and peripheral regions of the Laurentide and Fennoscandian ice sheets. Basal motion is accomplished via the deformation of unconsolidated sediments, or via sliding of the ice over an undeformable bed. We present an ice sheet [...]
Contrasting geomorphic and stratigraphic responses to normal fault development during single and multi-phase rifting
Published: 2021-07-27
Subjects: Earth Sciences, Geomorphology, Physical Sciences and Mathematics, Tectonics and Structure
Understanding the impact of tectonics on surface processes and the resultant stratigraphic evolution in multi-phase rifts is challenging, as patterns of erosion and deposition related to older phases of extension are overprinted by the subsequent extensional phases. In this study, we use a one-way coupled numerical modelling approach between a tectonic and a surface processes model to investigate [...]
Floods on alluvial fans: implications for reworking rates, morphology and fan hazards
Published: 2021-07-26
Subjects: Earth Sciences, Geomorphology, Physical Sciences and Mathematics
Flood events are the agents of change on alluvial fans. However, most alluvial fan experiments have used constant flows to model fans and the channels upon them. Here, we present results from a series of alluvial fan experiments with different patterns of flow variation (i.e. different hydrograph shapes). We conducted experiments with 1) constant flow, 2) alternating high and low flows, 3) a [...]
De-risking the energy transition by quantifying the uncertainties in fault stability
Published: 2021-07-26
Subjects: Earth Sciences, Environmental Sciences, Other Engineering, Risk Analysis
The operations needed to decarbonise our energy systems increasingly involve faulted rocks in the subsurface. To manage the technical challenges presented by these rocks and the justifiable public concern over induced seismicity, we need to assess the risks. Widely used measures for fault stability, including slip and dilation tendency and fracture susceptibility, can be combined with Response [...]
Kyanite petrogenesis in migmatites: Resolving melting and metamorphic signatures
Published: 2021-07-26
Subjects: Earth Sciences, Geochemistry, Geology
Aluminosilicates (kyanite, sillimanite and andalusite) are useful pressure-temperature (P-T) indicators that can form in a range of rock types through different mineral reactions, including those that involve partial melting. Their involvement in melting reactions means that the presence of aluminosilicates in migmatite mineral assemblages can help to (broadly) constrain the P-T conditions of [...]
VESIcal Part II: A critical approach to volatile solubility modelling using an open-source Python3 engine
Published: 2021-07-25
Subjects: Earth Sciences, Geology, Volcanology
Accurate models of H2O and CO2 solubility in silicate melts are vital for understanding volcanic plumbing systems. These models are used to estimate the depths of magma storage regions from melt inclusion volatile contents, investigate the role of volatile exsolution as a driver of volcanic eruptions, and track the degassing paths followed by magma ascending to the surface. However, despite the [...]