Preprints
Filtering by Subject: Earth Sciences
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 [...]
Large-Scale Controlled Experiment Demonstrates Effectiveness of Methane Leak Detection and Repair Programs at Oil and Gas Facilities
Published: 2021-12-10
Subjects: Earth Sciences, Environmental Sciences
The importance of reducing methane emissions from oil and gas operations as a near-term climate action is widely recognized. Most jurisdictions around the globe using leak detection and repair (LDAR) programs to find and fix methane leaks. In this work, we empirically evaluate the efficacy of LDAR programs using a large-scale, bottom-up, randomized controlled field experiment across ~200 oil and [...]
Catchment vegetation and erosion controls soil carbon cycling in south-eastern Australia during the last two Glacial-Interglacial cycles
Published: 2021-12-10
Subjects: Earth Sciences, Geochemistry, Geomorphology, Sedimentology
Deep Coseismic Slip in the Cascadia Megathrust can be Consistent with Coastal Subsidence
Published: 2021-12-09
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 [...]
Controls of the lithospheric thermal field of an ocean-continent subduction zone: the southern Central Andes
Published: 2021-12-08
Subjects: Earth Sciences
In an ocean-continent subduction zone, the assessment of the lithospheric thermal state is essential to determine the controls of the deformation within the upper plate and the dip angle of the subducting lithosphere. In this study, we evaluate the degree of influence of both the configuration of the upper plate and variations of the subduction angle on the lithospheric thermal field of 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 [...]
Evaluating essential features of proppant transport at engineering scales combining field measurements with machine learning algorithms
Published: 2021-12-06
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Environmental Sciences, Geology, Hydraulic Engineering, Oil, Gas, and Energy, Sustainability
The characterization of the proppant transport at a field-engineering scale is still challenging due to the lack of direct subsurface measurements. Features that control the proppant transport may link the experimental and numerical observations to the practical operations at a field scale. To improve the numerical and laboratory simulations, we propose a machine-learning-based workflow to [...]
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 [...]
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 [...]
Methane Fluxes of Vegetated Areas in Natural Freshwater Ecosystems: Assessments and Global Significance
Published: 2021-12-05
Subjects: Biogeochemistry, Earth Sciences, Environmental Sciences, Other Environmental Sciences
Freshwater ecosystems, including wetlands, lakes, and running waters, are estimated to contribute roughly 40% to global emissions of methane (CH4), a highly potent greenhouse gas. The emission of CH4 to the atmosphere entails the diffusive, ebullitive, and plant-mediated pathway. The latter, in particular, has been largely understudied and is neither well understood nor quantified. We have [...]
Coupled dynamics and evolution of primordial and recycled heterogeneity in Earth’s lower mantle
Published: 2021-12-04
Subjects: Earth Sciences, Planetary Sciences
The nature of compositional heterogeneity in Earth’s lower mantle remains a long-standing puzzle that can inform about the long-term thermochemical evolution and dynamics of our planet. Here, we use global-scale 2D models of thermo- chemical mantle convection to investigate the coupled evolution and mixing of (intrinsically-dense) recycled and (intrinsically- strong) primordial heterogeneity in [...]
Corona structures driven by plume-lithosphere interactions and evidence for ongoing plume activity on Venus
Published: 2021-12-04
Subjects: Earth Sciences, Physical Sciences and Mathematics, Planetary Sciences
In the absence of global plate tectonics, mantle convection and plume-lithosphere interaction are the main drivers of surface deformation on Venus. Among documented tectonic structures, circular volcano-tectonic features known as coronae may be the clearest surface manifestations of mantle plumes and hold clues to the global Venusian tectonic regime. Yet, the exact processes underlying coronae [...]
Competing feedback in an idealized tide-influenced delta network
Published: 2021-12-03
Subjects: Earth Sciences, Geomorphology, Physical Sciences and Mathematics
The morphodynamic evolution of river deltas is intimately tied to flow and sediment partitioning at bifurcations. In this work, the long-term equilibrium configuration of a simple delta network is investigated by means of an analytical model, which accounts for the effect of small tidal oscillations. Differently from individual bifurcations where tidal action is always a stabilizing factor, in [...]
Can machine learning improve carbon storage? Synergies of deep learning, uncertainty quantification and intelligent process control
Published: 2021-12-02
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Sustainability
As we transition from fossil fuel to renewable energy, negative emission technologies, such ascarbon capture and storage (CCS), can help us reduce CO2 emissions. Effective CO2 storage requires: (1) detailed site characterization, (2) regular, integrated risk assessment, and (3) flexible design and operation. We believe that recent advances in machine learning coupled with uncertainty [...]