Preprints
Filtering by Subject: Earth Sciences
What caused Earths largest mass extinction event? New evidence from the Permian-Triassic boundary in northeastern Utah
Published: 2018-02-26
Subjects: Biogeochemistry, Biology, Chemistry, Earth Sciences, Environmental Chemistry, Environmental Indicators and Impact Assessment, Environmental Sciences, Geology, Life Sciences, Paleobiology, Paleontology, Physical Sciences and Mathematics, Sedimentology
The discovery of a Permian-Triassic boundary section in northeastern Utah reveals a detailed record of events that led to one of the greatest mass extinctions on the planet. From 83% to 97% of the species living on the planet went extinct during this relatively short interval of geological time, which defines the major geological boundary between the Paleozoic and Mesozoic Eras. The cause and [...]
Probing earthquake dynamics through seismic radiated energy rate: illustration with the M7.8 2015 Nepal earthquake
Published: 2018-02-26
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Dynamic characterizations of earthquakes focus on whole-event representations, that is whether the total radiation of seismic waves is more or less energetic. Denolle et al (2015) and Yin et al. (2018) suggest to use the source spectrogram in order to analyze the radiation during the rupture itself. Here, we take a retrospective view on these studies to better establish the methodology of source [...]
Structure and kinematics of the Sumatran Fault System in North Sumatra (Indonesia)
Published: 2018-02-24
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
Lithospheric-scale faults related to oblique subduction are responsible for some of the most hazardous earthquakes reported worldwide. The mega-thrust in the Sunda sector of the Sumatran oblique subduction has been intensively studied, especially after the infamous 2004 Mw 9.1 earthquake, but its onshore kinematic complement within the Sumatran subduction, the transform Sumatran Fault System, has [...]
Groundwater controls on post-fire permafrost thaw: Water and energy balance effects
Published: 2018-02-22
Subjects: Earth Sciences, Environmental Sciences, Hydrology, Physical Sciences and Mathematics
Fire frequency and severity are increasing in high latitude regions, but the degree to which groundwater flow impacts the response of permafrost to fire remains poorly understood. Here, we use the Anaktuvuk River Fire (Alaska, USA) as an example for simulating groundwater-permafrost interactions following fire. We identify key thermal and hydrologic parameters controlling permafrost response to [...]
The new CLOCIT irradiation facility for 40Ar/39Ar geochronology: Characterization, comparison with CLICIT, and implications for high-precision geochronology
Published: 2018-02-20
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics
The Cadmium-Lined Outer-Core Irradiation Tube (CLOCIT) is a new irradiation facility for 40Ar/39Ar geochronology at the Oregon State University TRIGA® reactor. We report fluence parameters from the first four CLOCIT irradiations and compare them to the existing Cadmium-Lined Inner-Core Irradiation Tube (CLICIT). CLOCIT provides an average neutron flux equivalent of 1.45–1.53 ×10-4 J/h; about 55% [...]
Empirical relationship between river slope and the elongation of bars in braided rivers: a potential tool for paleoslope analysis from subsurface data
Published: 2018-02-20
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology
Paleoslope of ancient river systems is a fundamental parameter needed to reconstruct paleohydrology and paleoclimate from the fluvial sedimentary record. The shape of braid bars in 22 modern rivers yields a relationship between average bar elongation (length/width) and river slope. Steep rivers display more elongated bars than gently dipping reaches. This relationship has potential application to [...]
Active deformation of Malawi Rift’s North Basin hinge zone modulated by reactivation of pre-existing Precambrian shear zone fabric
Published: 2018-02-19
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Key Points: 1. Filtered aeromagnetic data elucidates the relationship between earthquake surface ruptures and buried faults along the North Basin hinge-zone, Malawi Rift. 2. Fault segments align with basement shear zone fabric. 3. Strain accommodation in the North Basin hinge zone is modulated by reactivation of the underlying Precambrian shear zone fabric. Abstract: We integrated temporal [...]
Fracture patterns associated with the evolution of the Teton anticline, Sawtooth Range, Montana, USA
Published: 2018-02-17
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
The Teton anticline and adjacent structures at the deformation front of the Sawtooth Range fold-thrust belt in Montana are fractured in such a way that some have used these as a model for the fractures that propagate during buckle folding. However, advances in understanding both the process of folding in forelands and the evolution of fracture patterns found within these folds suggests that it [...]
Aggradational lobe fringes: the influence of subtle intrabasinal seabed topography on sediment gravity flow processes and lobe stacking patterns
Published: 2018-02-16
Subjects: Earth Sciences, Physical Sciences and Mathematics, Sedimentology
Seabed topography is ubiquitous across basin-floor environments, and influences sediment gravity flows and sediment dispersal patterns. The impact of steep (several degrees) confining slopes on sedimentary facies and depositional architecture has been widely documented. However, the influence of gentle (fraction of a degree) confining slopes is less well-documented, largely due to outcrop [...]
Global assessment and mapping of changes in mesoscale landscapes: 1992–2015
Published: 2018-02-15
Subjects: Categorical Data Analysis, Computer Sciences, Earth Sciences, Environmental Sciences, Geographic Information Sciences, Geography, Longitudinal Data Analysis and Time Series, Numerical Analysis and Scientific Computing, Physical Sciences and Mathematics, Social and Behavioral Sciences, Spatial Science, Statistics and Probability
Monitoring global land cover changes is important because of concerns about their impact on environment and climate. The release by the European Space Agency (ESA) of a set of worldwide annual land cover maps covering the 1992–2015 period makes possible a quantitative assessment of land change on the global scale. While ESA land cover mapping effort was motivated by the need to better [...]
Towards machine ecoregionalization of Earth’s landmass using pattern segmentation method
Published: 2018-02-15
Subjects: Categorical Data Analysis, Computer Sciences, Earth Sciences, Environmental Sciences, Geographic Information Sciences, Geography, Numerical Analysis and Scientific Computing, Physical Sciences and Mathematics, Social and Behavioral Sciences, Spatial Science, Statistics and Probability
We present and evaluate a quantitative method for delineation of ecophysigraphic regions throughout the entire terrestrial landmass. The method uses the new pattern-based segmentation technique which attempts to emulate the qualitative, weight-of-evidence approach to a delineation of ecoregions in a computer code. An ecophysiographic region is characterized by homogeneous physiography defined by [...]
Global inventory of landscape patterns and latent variables of landscape spatial configuration
Published: 2018-02-15
Subjects: Biodiversity, Earth Sciences, Environmental Indicators and Impact Assessment, Environmental Sciences, Geographic Information Sciences, Geography, Life Sciences, Physical Sciences and Mathematics, Social and Behavioral Sciences, Spatial Science
We present a regionalization of the entire Earth’s landmass into land units of homogeneous landscape patterns. The input to the regionalization is a high resolution Global Land Cover (GLC) dataset. The GLC is first divided into local landscapes – small non-overlapping square blocks of GLC cells. These blocks are agglomerated into much larger land units using a pattern-based segmentation [...]
Outcrop-scale tomography: insights into the 3D structure of multiphase boudins
Published: 2018-02-15
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
We analyze the 3D geomorphology of a boudinaged amphibolite layer encased in marble using meter-scale tomography by serial sectioning, high resolution imaging and 3D reconstruction of a 2 m³ block from a quarry in the high-grade core of the Naxos core complex. Local uncertainties in the model are resolved by dissolution of marble in selected slabs, yielding a large, highly accurate 3D [...]
What is users next best alternative to the use of dynamical seasonal predictions?
Published: 2018-02-14
Subjects: Earth Sciences, Physical Sciences and Mathematics
The recent development of climate predictions has shown their potential in providing users with information that could be used to inform decision on a seasonal time-horizon. This in turns offers a way of developing resilience to climate change through adaptation to seasonal variability. An effective way to assess to value of this information is to compare the quality of the forecast (assessed by [...]
Application of discrete-element methods to approximate sea-ice dynamics
Published: 2018-02-14
Subjects: Earth Sciences, Glaciology, Oceanography and Atmospheric Sciences and Meteorology, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics
Lagrangian models of sea-ice dynamics have several advantages over Eulerian continuum models. Spatial discretization on the ice-floe scale are natural for Lagrangian models and offer exact solutions for mechanical non-linearities with arbitrary sea-ice concentrations. This allows for improved model performance in ice-marginal zones. Furthermore, Lagrangian models can explicitly simulate jamming [...]