Preprints
Filtering by Subject: Earth Sciences
Segregation of bare and protonated Mg vacancies to dislocation cores in MgO
Published: 2018-09-27
Subjects: Earth Sciences, Mineral Physics, Physical Sciences and Mathematics
Water can be incorporated into the lattice of mantle minerals in the form of protons charge-balanced by the creation of cation vacancies. These protonated vacancies, when they interact with dislocations, increase strain rates by enhancing dislocation climb and, potentially, by reducing the Peierls barrier to glide. We use atomic scale simulations to investigate segregation of Mg vacancies to [...]
Atomistic simulations of Mg vacancy segregation to dislocation cores in forsterite
Published: 2018-09-27
Subjects: Earth Sciences, Mineral Physics, Physical Sciences and Mathematics
Interactions between dislocations in olivine and extrinsic cation vacancies created under hydrous or oxidizing conditions may influence the rheology of the Earths upper mantle. In this study, we use atomic-scale simulations to calculate segregation energies for bare and protonated Mg vacancies to M1 and M2 sites in the core regions of [100](010) and [001](010) edge dislocations, and [100] and [...]
High-temperature shear zone formation in Carrara marble: The effect of loading conditions
Published: 2018-09-26
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Rock deformation at depths in the Earth’s crust is often localized in high temperature shear zones occurring at different scales in a variety of lithologies. The presence of material heterogeneities is known to trigger shear zone development, but the mechanisms controlling initiation and evolution of localization are not fully understood. To investigate the effect of loading conditions on shear [...]
Pleistocene-Holocene tectonic reconstruction of the Ballık travertine (Denizli Graben, SW Turkey): (De)formation of large travertine geobodies at intersecting grabens
Published: 2018-09-25
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Travertine geobodies have been identified as potential reservoir analogues to carbonate build-ups in pre-salt hydrocarbon systems. To investigate travertine geobody deformation, faults were mapped in 35 travertine quarries that excavate the Ballık travertine, i.e. a c. 12.5 km2 large travertine geobody that precipitated at the intersection of the NE margin of the Denizli Basin and neighbouring [...]
Interpretation of low‐temperature thermochronometer ages from tilted normal fault blocks
Published: 2018-09-25
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Low-temperature thermochronometry is a widely-used tool for dating the timing and rate of slip on normal faults. Rates are often derived from suites of footwall thermochronometer samples, but simple 2D regression of age vs. structural depth fails to account for the fact that rocks collected at similar elevations today experienced curved particle trajectories and variable velocities during fault [...]
Statistics and segmentation: Using Big Data to assess Cascades Arc compositional variability
Published: 2018-09-24
Subjects: Applied Mathematics, Applied Statistics, Earth Sciences, Geochemistry, Geology, Multivariate Analysis, Physical Sciences and Mathematics, Statistics and Probability, Volcanology
Primitive lavas erupted in the Cascades arc of western North America demonstrate significant patterns of along-arc heterogeneity. Such compositional diversity may be the result of differences in mantle melting processes, subduction geometry, regional tectonics, or compositions of the slab, mantle or overlying lithosphere. Previous authors have partitioned the arc into four geochemically distinct [...]
Wind tunnel tests inform Ammophila planting spacing for dune management
Published: 2018-09-24
Subjects: Biology, Earth Sciences, Environmental Sciences, Geology, Geomorphology, Life Sciences, Natural Resources Management and Policy, Physical Sciences and Mathematics, Sedimentology
Coastal dunes are invaluable natural resources that bu er upland areas. Vegetation is key in dune development and stabilization. Dunes form with sufficient wind, sand source, and obstruction; plants are the ideal obstruction. Storms o en erode foredunes and coastal managers replant vegetation to re-establish the necessary obstruction for sand accretion and dune growth. We used a wind tunnel to [...]
Reactionary fence installation for post-Superstorm Sandy dune recovery
Published: 2018-09-24
Subjects: Biology, Earth Sciences, Environmental Monitoring, Environmental Sciences, Life Sciences, Natural Resources and Conservation, Physical Sciences and Mathematics, Sedimentology, Sustainability
Dunes are invaluable to coastal areas as dynamic buffers to erosion during high tides and storms, but do not accrue naturally in developed areas without assistance. Wood paling fencing is commonly used to cultivate dune development and thereby increase the protection afforded to coastal areas. In 2012, Superstorm Sandy devastated the mid-Atlantic, especially New Jersey where many areas are still [...]
A New Mechanism for Terrace Formation in Submarine Canyons
Published: 2018-09-24
Subjects: Earth Sciences, Education, Engineering, Geology, Geomorphology, Life Sciences, Physical Sciences and Mathematics, Planetary Geomorphology, Planetary Sciences, Planetary Sedimentology, Sedimentology, Stratigraphy
Deep canyons on Earth occur in both terrestrial and submarine environments, where they are carved by actively incising channels. Apparently similar flights of unpaired terraces, seen at the inside of bends in incised sinuous channels, are also common in both environments. Here we demonstrate a new mechanism for terrace formation that we believe is unique to settings where sediment transporting [...]
The origin and role of biological rock crusts in rocky desert weathering
Published: 2018-09-24
Subjects: Earth Sciences, Environmental Microbiology and Microbial Ecology Life Sciences, Geomorphology, Life Sciences, Microbiology, Physical Sciences and Mathematics
In drylands, microbes that colonise rock surfaces were linked to erosion because water scarcity excludes traditional weathering mechanisms. We studied the origin and role of rock biofilms in geomorphic processes of hard lime and dolomitic rocks that feature comparable weathering morphologies though originating from arid and hyperarid environments, respectively. We hypothesised that weathering [...]
Bedrock Fracture Influences on Geomorphic Process and Form Across Process Domains and Scales
Published: 2018-09-24
Subjects: Earth Sciences, Geomorphology, Physical Sciences and Mathematics
Fractures are discontinuities in rock that can be exploited by erosion. Fractures regulate cohesion, profoundly affecting the rate, style, and location of Earth surface processes. By modulating the spatial distribution of erodibility, fractures can focus erosion and set the shape of features from scales of fluvial bedforms to entire landscapes. Although early investigation focused on fractures as [...]
Backwater Controls on the Sedimentology, Kinematics and Geometry of Bar Deposits in Coastal Rivers
Published: 2018-09-24
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Environmental Engineering, Geology, Geomorphology, Hydrology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
The backwater reach of coastal rivers is associated with considerable spatial and temporal variability in water and sediment flux. Here we test the hypothesis that the spatial and temporal variability in water flux and particle sizes in transport result in systematic changes in the geometry of bank-attached bars across the backwater transition. Measured transverse slopes of bank-attached bars in [...]
Grand Challenges (and Great Opportunities) in Sedimentology, Stratigraphy, and Diagenesis Research
Published: 2018-09-23
Subjects: Biogeochemistry, Earth Sciences, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Technological advances make these exciting times for geoscientists studying Earth surface processes, their depositional products, and interactions with the biosphere, hydrosphere, atmosphere, and lithosphere; from monitoring contemporary sediment transport processes to interpretation of sedimentary archives that record ancient environmental changes. We set out three research challenges: 1) [...]
Complex and cascading triggering of submarine landslides and turbidity currents at volcanic islands revealed from integration of high-resolution onshore and offshore surveys
Published: 2018-09-22
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Hydrology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy, Volcanology
Submerged flanks of volcanic islands are prone to hazards including submarine landslides that may trigger damaging tsunamis and fast-moving sediment-laden seafloor flows (turbidity currents) that break critical seafloor infrastructure. Small Island Developing States are particularly vulnerable to these hazards due to their remote and isolated nature, small size, high population densities and weak [...]
Response of Marine-Terminating Glaciers to Forcing: Time Scales, Sensitivities, Instabilities and Stochastic Dynamics
Published: 2018-09-20
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
Recent observations indicate that many marine‐terminating glaciers in Greenland and Antarctica are currently retreating and thinning, potentially due to long‐term trends in climate forcing. In this study, we describe a simple two‐stage model that accurately emulates the response to external forcing of marine‐terminating glaciers simulated in a spatially extended model. The simplicity of the model [...]