Preprints
Filtering by Subject: Earth Sciences
The composition and weathering of the continents over geologic time
Published: 2020-08-21
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics
The composition of continental crust records a history of construction by tectonics and destruction by physical and chemical erosion. Quantitative constraints on how both igneous addition and chemical weathering have modified the continents bulk composition are essential for understanding the evolution of geodynamics and climate. We have extracted temporal trends in sediments protolith [...]
GARPOS: analysis software for the GNSS-A seafloor positioning with simultaneous estimation of sound speed structure
Published: 2020-08-21
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Global Navigation Satellite System – Acoustic ranging combined seafloor geodetic technique (GNSS-A) has extended the geodetic observation network into the ocean. The key issue for analyzing the GNSS-A data is how to correct the effect of sound speed variation in the seawater. We constructed a generalized observation equation and developed a method to directly extract the gradient sound speed [...]
Computing single-particle flotation kinetics using automated mineralogy data and machine learning
Published: 2020-08-21
Subjects: Earth Sciences, Engineering, Geology, Mining Engineering, Physical Sciences and Mathematics
Studies of flotation kinetics are essential for understanding, predicting, and optimizing the selective recovery of minerals and metals through flotation. Recently, much effort has been made to use intrinsic ore properties to model flotation behavior. Particle-based characterization methods, e.g. SEM-based image analysis, has enabled much of this development. However, currently available methods [...]
Quantification of non-linear multiphase flow in porous media
Published: 2020-08-20
Subjects: Earth Sciences, Engineering, Hydrology, Life Sciences, Medicine and Health Sciences, Mineral Physics, Physical Sciences and Mathematics
We measure the pressure difference during two-phase flow across a sandstone sample for a range of injection rates and fractional flows of water, the wetting phase, during an imbibition experiment. We quantify the onset of a transition from a linear relationship between flow rate and pressure gradient to a non-linear power-law dependence. We show that the transition from linear (Darcy) to [...]
An Integrated Flood Risk Assessment and Mitigation Framework: Middle Cedar River Basin Case Study
Published: 2020-08-20
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Environmental Sciences, Physical Sciences and Mathematics, Water Resource Management
Property buyout is one of the most frequently preferred flood mitigation applications by decision-makers for long-term risk reduction. Due to its high-level funding requirements as a mitigation solution, it requires extensive benefits and costs analysis for the selected region. Many communities in the State of Iowa experienced flood events (i.e. 1993, 2008, 2014, 2019) which resulted in a heavy [...]
A unifying basis for the interplay of stress and chemical processes in the Earth: support from diverse experiments
Published: 2020-08-20
Subjects: Earth Sciences, Physical Sciences and Mathematics
The Earth is under stress on all scales from individual grains to the entire crust and mantle. Mineral reactions, including pressure solution and diffusion creep, occur in that context. Whilst the effect of pressure on mineral reactions is understood through well established thermodynamics, the effect of stress on mineral reactions is not. Here I show that a particular equation linking stress and [...]
The Ediacaran Grenville dykes (SE Canada) reveal the weakest sustained palaeomagnetic field on record.
Published: 2020-08-20
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Long-term variations of the geomagnetic field, observed in the palaeomagnetic record, have the potential to shed much light on the evolution of Earth’s deep interior. With a geomagnetic field characterised by anomalous directions and ultra-low intensities, the Ediacaran period (635-541 Ma) is a time of special interest. Steep and shallow directions, leading to virtual geomagnetic poles (VGPs), [...]
A prototype for a Multi-GNSS orbit combination
Published: 2020-08-20
Subjects: Astrophysics and Astronomy, Earth Sciences, Other Astrophysics and Astronomy, Other Earth Sciences, Physical Sciences and Mathematics
Since 1994, the International GNSS Service (IGS) provides a combination of orbit and clock offset products from its different Analysis Centers. These products are used as input by many software for countless scientific and/or operational applications. They can also be used as an independent reference for benchmark experiments. Nevertheless, those products include GPS-only data, despite the fact [...]
Structure of the North Anatolian Fault Zone imaged via teleseismic scattering tomography
Published: 2020-08-20
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Information on fault zone structure is essential for our understanding of earthquake mechanics, continental deformation and our understanding of seismic hazard. We use the scattered seismic wavefield to study the subsurface structure of the North-Anatolian Fault Zone (NAFZ) in the region of the 1999 {\.I}zmit and D\"uzce rupture using data from an 18-month dense deployment of seismometers with a [...]
Quantitative estimates of average geomagnetic axial dipole dominance in deep geological time
Published: 2020-08-20
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
A defining characteristic of the recent geomagnetic field is its dominant axial dipole which provides its navigational utility and dictates the shape of the magnetosphere. Going back through time, much less is known about the degree of axial dipole dominance. Here we use a substantial and diverse set of 3D numerical dynamo simulations and recent observation-based field models to derive a power [...]
The 23 June 2020, Mw 7.4 La Crucecita, Oaxaca, Mexico earthquake and tsunami: A Rapid Response Field Survey during COVID-19 crisis
Published: 2020-08-19
Subjects: Earth Sciences, Other Earth Sciences, Physical Sciences and Mathematics
The 23 June 2020 La Crucecita earthquake occurred at 10:29 hr on the coast of Oaxaca in a Mw 7.4 megathrust event at 22.6 km depth, and triggered a tsunami recorded at Huatulco and Salina Cruz tide gauge stations and a DART off the coast of Mexico. Immediately after the earthquake, a rapid response effort was coordinated by members of the Tsunami and Paleoseismology Laboratory UNAM, despite the [...]
Evolution of normal fault displacement and length as the continental lithosphere stretches
Published: 2020-08-17
Subjects: Earth Sciences, Life Sciences, Physical Sciences and Mathematics
Continental rifting is accommodated by the development of normal fault arrays. Fault growth patterns control their related seismic hazards, as well as influencing the tectonostratigraphic evolution, resource extraction and CO2 storage potential of rifts. Our understanding of fault evolution is largely derived by observing the final geometry and displacement (D)-length (L) characteristics of [...]
Apatite fission-track dating by LA-Q-ICP-MS mapping
Published: 2020-08-17
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics
Obtaining accurate and precise apatite fission-track (AFT) ages is dependent on producing plentiful high-quality apatite grains from a sample, ideally with high spontaneous fission-track densities (c. >105 tracks.cm-2). Many natural samples, such as bedrock samples from young orogenic belts or low-grade metamorphic samples with low U contents yield low spontaneous fission-track densities. Such [...]
Resolving the Kinematics and Moment Release of Early Afterslip within the First Hours following the 2016 Mw 7.1 Kumamoto Earthquake: Implications for the Shallow Slip Deficit and Frictional Behavior of Aseismic Creep
Published: 2020-08-17
Subjects: Earth Sciences, Environmental Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Continuous measurements of postseismic surface deformation provide insight into variations of the frictional strength of faults and the rheology of the lower crust and upper mantle as stresses following rupture are dissipated. However, due to the difficulty of capturing the earliest phase of afterslip, most analyses have focused on understanding postseismic processes over timescales of [...]
Diversity Crisis in UK Geoscience Research Training
Published: 2020-08-17
Subjects: Earth Sciences, Physical Sciences and Mathematics
Geoscientists have a key role to play in the great challenges of the 21st Century, but solving these problems requires diverse collaborations and engagement with stakeholders from all backgrounds, both in the fundamental science and its implementation. How can we break down the barriers that have made Geoscience amongst the worst for racial minority representation and make our discipline [...]