Preprints
Filtering by Subject: Earth Sciences
Role of strain-dependent weakening memory on the style of mantle convection and plate boundary stability
Published: 2019-03-28
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
How plate tectonic surface motions relate to the convecting mantle remains one of the major problems in geosciences. In particular, the cause and consequence of strain localization at plate boundaries remains debated, even though strain memory, i.e. the ability to preserve and reactivate tectonic inheritance over geological time, appears to be a critical feature in plate tectonics. Here, we [...]
3-D seismic images of an extensive igneous sill in the lower crust
Published: 2019-03-28
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
When continents rift, magmatism can produce large volumes of melt that migrate upwards from deep below the Earth’s surface. To understand how magmatism impacts rifting, it is critical to understand how much melt is generated and how it transits the crust. Estimating melt volumes and pathways is difficult, however, particularly in the lower crust where the resolution of geophysical techniques is [...]
Seismic expression of shear zones: insights from 2-D convolution seismic modelling
Published: 2019-03-28
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
During extension, compression or strike-slip motion, shear zones accommodate large amountsof strain in the crust. Our understanding of these processes critically depends on our ability torecognize shear zones in the subsurface. The exact signature of shear zones in seismic reflectiondata is however not well understood. To advance our understanding, we simulate how threeoutcrop examples of [...]
Agriculture-aquaculture transitions on the lower Ganges-Brahmaputra Delta, 1972-2017
Published: 2019-03-25
Subjects: Earth Sciences, Environmental Indicators and Impact Assessment, Environmental Monitoring, Environmental Sciences, Natural Resources and Conservation, Natural Resources Management and Policy, Other Earth Sciences, Other Environmental Sciences, Physical Sciences and Mathematics, Sustainability
Recent decades have seen a considerable increase in shrimp aquaculture in tropical and subtropical developing countries. This practice is controversial due to its potential for serious economic, food security, and environmental impacts. Of particular concern is the widespread practice of intensive aquaculture in and near mangrove ecosystems where many shrimp species spawn. However, while [...]
Effects of turbulent hyporheic mixing on reach-scale transport
Published: 2019-03-25
Subjects: Earth Sciences, Hydrology, Physical Sciences and Mathematics
Turbulence causes rapid mixing of solutes and fine particles between open channel flow and coarse-grained streambeds. Turbulent mixing is known to control hyporheic exchange fluxes and the distribution of vertical mixing rates in the streambed, but it is unclear how turbulent mixing ultimately influences mass transport at the reach scale. We used a particle-tracking model to simulate local- and [...]
Outer Trench Slope Flexure and Faulting at Pacific Basin Subduction Zones
Published: 2019-03-22
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Flexure and fracturing of the seafloor on the outer trench wall of subduction zones reflects bending of the lithosphere beyond its elastic limit. To investigate these inelastic processes, we have developed a full non-linear inversion approach for estimating the bending moment, curvature, and outer trench wall fracturing using shipboard bathymetry and satellite altimetry derived gravity data as [...]
The Impact of Melting Ice Sheets on Future Global Climate
Published: 2019-03-22
Subjects: Climate, Earth Sciences, Hydrology, Oceanography and Atmospheric Sciences and Meteorology, Other Earth Sciences, Physical Sciences and Mathematics, Physics
That is a preprint of an article suubmitted at Applied Greography (20tf of March 19). Climate change studies in the last decades have been based on Global Climate Models (GCM), and the distribution of climatic regions over time extracted from these models can be represented using the Köppen climatic classification. The Köppen approach predicts the distribution of biomes worldwide on the basis of [...]
The competition for salt and kinematic interactions between minibasins during density-driven subsidence: observations from numerical models
Published: 2019-03-21
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Stratal geometries of salt-floored minibasins provide a record of the interplay between minibasin subsidence and sedimentation. Minibasin subsidence and resulting stratal geometries are frequently interpreted by considering the minibasins in isolation and implicitly assuming that internal geometries are the result of purely vertical halokinetic processes. However, minibasins rarely form in [...]
Temporally constant Quaternary uplift rates and their relationship with extensional upper-plate faults in south Crete (Greece), constrained with 36Cl exposure dating.
Published: 2019-03-21
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Preserved sets of marine terraces and palaeoshorelines above subduction zones provide an opportunity to explore the long-term deformation that occurs as a result of upper-plate extension. We investigate uplifted palaeoshorelines along the South Central Crete Fault and over its western tip, located above the Hellenic Subduction Zone, in order to derive uplift rates and examine the role that known [...]
Anthropogenic activities alter drought termination
Published: 2019-03-19
Subjects: Earth Sciences, Environmental Sciences, Hydrology, Physical Sciences and Mathematics, Water Resource Management
Despite the increasing influence of human activities on water resources in our current Anthropocene era, the impacts of these activities on the duration, rate and timing of the recovery of drought events, known as the drought termination phase, remain unknown. Here, we present the first assessment of how different human activities (i.e. water abstractions, reservoirs, water transfers) affect [...]
Direct observations of the coupling between quartz dissolution and Mg-silicate formation
Published: 2019-03-19
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics
Although quartz is a stable mineral at Earth surface conditions, field samples have shown its rapid dissolution in combination with the precipitation of Mg-silicate phases. Atomic force microscopy (AFM) experiments were performed to investigate the dissolution of quartz and the precipitation of secondary phases in high-pH, Mg-rich solutions both in-situ and ex-situ. Experiments were conducted at [...]
Numerical wave propagation through ice-covered regions
Published: 2019-03-19
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
In recent years, seismic station coverage in polar regions has been increasing steadily, providing new insight into the deep structure and dynamics of these remote parts of the globe. Numerical seismic wave propagation through polar regions is complicated by the presence of ice sheets. At periods relevant for regional-scale waveform tomography, the ice acts as a thin layer that, for an exact [...]
Formation of magnesium silicate hydrate cement in nature
Published: 2019-03-19
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology
Tillite lithified by magnesium silicate hydrate (M-S-H) cement has been formed at the surface of the Feragen Ultramafic Body in SE Norway. Serpentinization of olivine-rich rocks led to formation of brucite that dissolves during weathering to form a high pH (>9) Mg-rich fluid. This fluid dissolves quartz deposited by glaciers during the Weichselian glaciation. Subsequent evaporation leads to [...]
Obstructed Minibasins on a Salt-Detached Slope: An Example from above the Sigsbee Canopy, Northern Gulf of Mexico
Published: 2019-03-19
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
Salt-detached gravity-gliding/spreading systems having a rugose base-of-salt display complex strain patterns. However, little was previously known about how welding of supra-salt minibasins to the sub-salt may influence both the downslope translation of minibasins on salt-detached slopes and the regional pattern of supra-salt strain. Using a regional 3D seismic reflection data set, we examine a [...]
Segmentation of rifts through structural inheritance: Creation of the Davis Strait
Published: 2019-03-19
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Mesozoic-Cenozoic rifting between Greenland and North America created the Labrador Sea and Baffin Bay, while leaving preserved continental lithosphere in the Davis Strait which lies between them. Inherited crustal structures from a Palaeoproterozoic collision have been hypothesized to account for the tectonic features of this rift system. However, the role of mantle lithosphere heterogeneities in [...]