Preprints
Filtering by Subject: Physical Sciences and Mathematics
Mineralogy and diagenesis of Mars-analog paleosols from eastern Oregon, USA
Published: 2021-12-16
Subjects: Physical Sciences and Mathematics
Ancient (4.1-3.7-billion-year-old) layered sedimentary rocks on Mars are rich in clay minerals which formed from aqueous alteration of the Martian surface. Many of these sedimentary rocks appear to be composed of vertical sequences of Fe/Mg clay minerals overlain by Al clay minerals that resemble paleosols (ancient, buried soils) from Earth. The types and properties of minerals in paleosols can [...]
Detection of organic carbon in Mars-analog paleosols with thermal and evolved gas analysis
Published: 2021-12-16
Subjects: Physical Sciences and Mathematics
Ancient, buried soils, or paleosols, may have been preserved in the geological record on Mars, and are considered high-priority targets for biosignature investigation. Studies of paleosols on Earth that are similar in composition to putative martian paleosols can provide a reference frame for constraining their organic preservation potential on Mars. However, terrestrial paleosols typically [...]
Challenges and uncertainty in plot-scale emissivity and surface temperature estimation using flux tower measurements
Published: 2021-12-15
Subjects: Physical Sciences and Mathematics
Land surface temperature (LST) is a preeminent state variable that controls the energy and water exchange between the Earth’s surface and the atmosphere. At the landscape-scale, LST is derived from thermal infrared radiance measured using space-borne radiometers. At the plot-scale, the flux tower recorded longwave radiation components are inverted to retrieve LST. Since the down-welling longwave [...]
Global trends in novel stable isotopes in basalts: theory and observations
Published: 2021-12-14
Subjects: Physical Sciences and Mathematics
The geochemistry of global mantle melts suggests that both mid-ocean ridge basalts (MORB) and ocean island basalts (OIB) sample lithological and temperature heterogeneities originating in both the upper and lower mantle. Recently, non-traditional stable isotopes have been suggested as a new tool to complement existing tracers of mantle heterogeneity (e.g., major and trace elements, radiogenic [...]
Thermochemical structure and evolution of cratonic lithosphere in central and southern Africa
Published: 2021-12-10
Subjects: Earth Sciences, Geochemistry, Geophysics and Seismology, Mineral Physics, Physical Sciences and Mathematics, Tectonics and Structure
The thermochemical structure of the subcontinental mantle holds information on its origin and evolution that can inform energy and mineral exploration strategies, natural hazard mitigation and evolutionary models of the Earth. However, imaging the fine-scale thermochemical structure of continental lithosphere remains a major challenge. Here we combine multiple land and satellite datasets via [...]
Elevated Post K-Pg Export Productivity in the Gulf of Mexico and Caribbean
Published: 2021-12-10
Subjects: Earth Sciences, Geochemistry, Paleobiology, Paleontology, Physical Sciences and Mathematics
The global heterogeneity in export productivity after the Cretaceous-Paleogene (K-Pg) mass extinction is well documented, with some sites showing no change on geologic timescales, some demonstrating sustained decline, and a few showing a somewhat surprising increase. However, observational data come from sites so widespread that a key outstanding question is the geographic scale of changes in [...]
Multi-proxy assessment of surface sediments using APPI-P FTICR-MS reveals a complex biogeochemical record along a salinity gradient in the Pearl River estuary and coastal South China Sea
Published: 2021-12-10
Subjects: Analytical Chemistry, Biogeochemistry, Chemistry, Earth Sciences, Environmental Chemistry, Environmental Monitoring, Environmental Sciences, Geochemistry, Physical Sciences and Mathematics
The Pearl River drains the second largest watershed in China, funnelling large amounts of freshwater and organic matter into the northern part of the South China Sea through an estuary characterized by pronounced biogeochemical gradients. In this study we analyzed organic extracts of surface sediments collected along land-sea transect that captures a transition from freshwater environment at the [...]
Deep Coseismic Slip in the Cascadia Megathrust can be Consistent with Coastal Subsidence
Published: 2021-12-08
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
At subduction zones, the down-dip limit of slip represents how deep an earthquake can rupture. For hazards it is important - it controls the intensity of shaking and the pattern of coseismic uplift and subsidence. In the Cascadia Subduction Zone, because no large magnitude events have been observed in instrumental times, the limit is inferred from geological estimates of coastal subsidence during [...]
A conceptual geological model for offshore wind sites in palaeo ice stream settings: The Utsira Nord site, North Sea
Published: 2021-12-06
Subjects: Physical Sciences and Mathematics
Conceptual geological models of the shallow subsurface which integrate geological and geotechnical information are important for more strategic data acquisition and engineering at offshore wind sites. Utsira Nord is an offshore wind site in the Norwegian North Sea. It covers an area of 23 km x 43 km within the Norwegian Channel palaeo ice stream, with an average water depth of 267 m making the [...]
COVID-19 Impacts Highlight the Need for Holistic Evaluation of Research in the Hydrologic Sciences
Published: 2021-12-06
Subjects: Earth Sciences, Hydrology, Physical Sciences and Mathematics
As we reckon with the effect of COVID-19 on the research enterprise in hydrologic science, it is important to acknowledge that disruptions will be persistent and that institutional-level adjustments, while helpful, are not sufficient to mitigate all impacts on hydrologic scientists. Here, we describe the breadth of research contributions in the hydrologic sciences, consider how the pandemic has [...]
Spatio-temporal clustering of seismicity enabled by off-fault plasticity
Published: 2021-12-06
Subjects: Applied Mechanics, Civil and Environmental Engineering, Dynamics and Dynamical Systems, Earth Sciences, Engineering, Engineering Mechanics, Engineering Science and Materials, Geophysics and Seismology, Mechanical Engineering, Mechanics of Materials, Other Mechanical Engineering, Physical Sciences and Mathematics, Tribology
While significant progress has been made in understanding earthquake source processes in linear elastic domains, the effect of more realistic rheologies including plasticity is poorly understood. Here, we simulate sequence of earthquake and aseismic slip of a 2D antiplane rate-and-state fault embedded in a full-space elastic-plastic bulk. We show that off-fault plasticity may lead to partial [...]
Sequences of seismic and aseismic slip on bimaterial faults show dominant rupture asymmetry and potential for elevated seismic hazard
Published: 2021-12-06
Subjects: Physical Sciences and Mathematics
We perform numerical simulations of sequences of earthquake and aseismic slip on planar rate and state faults separating dissimilar material within the 2-D plane strain approximation. We resolve all stages of the earthquake cycle from aseismic slip to fast ruptures while incorporating full inertia effects during seismic event propagation. We show that bimaterial coupling results in favorable [...]
Timing of oil expulsion from source rocks and a revitalization of the pre-1970 model
Published: 2021-12-06
Subjects: Earth Sciences, Physical Sciences and Mathematics
New data from North Sea Upper Jurassic source rock samples show no decline in the total amount of organic matter (TOC) within the oil expulsion window between 120 and 150°C which is a key prediction by today’s model for oil expulsion. However, today’s model for oil expulsion is not consistent with either subsurface source rock TOC data or chemical attributes of shallow oils. Instead, these data [...]
Supraglacial debris thickness and supply rate in High-Mountain Asia
Published: 2021-12-05
Subjects: Physical Sciences and Mathematics
Supraglacial debris strongly modulates glacier melt rates and can be decisive for ice dynamics and mountain hydrology. It is ubiquitous in High-Mountain Asia (HMA), yet because its thickness and supply rate from local topography are poorly known, our ability to forecast regional glacier change and streamflow is limited. Here we resolved the spatial distribution of supraglacial debris thickness [...]
High-magnitude stresses induced by mineral-hydration reactions
Published: 2021-12-04
Subjects: Physical Sciences and Mathematics
Fluid-rock interactions play a critical role in Earth’s lithosphere and in engineered subsurface systems. In the absence of chemical mass transport, mineral-hydration reactions will be accompanied by a solid-volume increase that may induce differential stresses and associated reaction-induced deformation processes, such as dilatant fracturing to increase fluid permeability. However, the [...]