Preprints
Filtering by Subject: Physical Sciences and Mathematics
Evolution of the melt source during protracted crustal anatexis; an example from the Bhutan Himalaya
Published: 2019-10-10
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics
The chemical compositions of growth zones of magmatic zircon provide powerful insight into evolving magma compositions due to their ability to record both time and the local chemical environment. In situ U-Pb and Hf isotope analyses of zircon rims from Tertiary leucogranites of the Bhutan Himalaya reveal, for the first time, an evolution in melt composition between 32-12 Ma. The data indicate a [...]
Lower threshold for marsh drowning suggests loss of microtidal marshes regardless of sediment supply
Published: 2019-10-10
Subjects: Earth Sciences, Environmental Sciences, Geomorphology, Natural Resources and Conservation, Physical Sciences and Mathematics
Salt marshes are simultaneously among the most valuable and vulnerable ecosystems in the world. We use a simplified formulation for sediment transport across marshes to explain why marshes are most vulnerable to sea level rise (SLR) in microtidal environments. We find inorganic sediment decay length scales with tidal range so that inorganic deposition is very low in the interior of microtidal [...]
Four-dimensional Variability of Composite Halokinetic Sequences
Published: 2019-10-10
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
The architecture of salt diapir-flank strata (i.e. halokinetic sequences) is controlled by the interplay between volumetric diapiric flux and sediment accumulation rate. Halokinetic sequences consist of unconformity-bounded packages of thinned and folded strata formed by drape-folding around passive diapirs. These sequences are described by two end-members: (i) hooks, which are characterized by [...]
Relative Dispersion in the Antarctic Circumpolar Current
Published: 2019-10-09
Subjects: Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
We present an analysis of relative dispersion and associated metrics from the RAFOS float observations collected during the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES) along with a set of particles from an eddy-resolving numerical model that simulated the flow in the DIMES region. Both RAFOS floats and numerical particles show correlated motions and isotropic pair [...]
Deep and rapid thermo-mechanical erosion by a small-volume lava flow
Published: 2019-10-08
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology
We document remarkably efficient thermo-mechanical erosion by a small-volume lava flow. Downcutting by a basaltic-andesite lava flow on the steep-sided Momotombo volcano, Nicaragua, occurred at 100 times the rate commonly reported for thermal erosion in lava flow fields, even though this flow was small-volume (0.02 km^3) and effused at a low rate for <1 week. The erosion depth, up to 30 m [...]
Machine learning on field data for hydraulic fracturing design optimization
Published: 2019-10-08
Subjects: Engineering, Physical Sciences and Mathematics
Growing amount of fracturing stimulation jobs in the recent two decades resulted in a significant amount of measured data available for construction of predictive models via machine learning (ML). Simulataneous evolution of machine learning has made it possible to apply algorithms on the hydraulic fracture database. A typical multistage fracturing job on a near-horizontal well today involves a [...]
Crack to pulse transition and magnitude statistics during earthquake cycles on a self-similar rough fault
Published: 2019-10-08
Subjects: Earth Sciences, Engineering, Geophysics and Seismology, Mechanical Engineering, Physical Sciences and Mathematics, Tectonics and Structure, Tribology
Faults in nature demonstrate fluctuations from planarity at most length scales that are relevant for earthquake dynamics. These fluctuations may influence all stages of the seismic cycle; earthquake nucleation, propagation, arrest, and inter-seismic behavior. Here I show quasi-dynamic plane-strain simulations of earthquake cycles on a self-similar and finite 10 km long rough fault with [...]
Asperity failure control of stick-slip along brittle faults
Published: 2019-10-08
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
Stick-slips are spontaneous, unstable slip events during which a natural or man-made system transitions from a strong, sticking stage to a weaker, slipping stage. Stick-slips were proposed by Brace and Byerlee (1966) as the experimental analogue of natural earthquakes. We analyze here the mechanics of stick-slips along brittle faults by conducting laboratory experiments and by modeling the [...]
Metastable olivine wedge beneath the Japan Sea imaged by seismic interferometry
Published: 2019-10-08
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The metastable olivine wedge (MOW) within subducted slabs has long been hypothesized to host deep-focus earthquakes (>300 km). Its presence would also rule out hydrous slabs being subducted into the mantle transition zone. However, the existence and dimensions of MOW remain controversial. Here, we apply inter-source interferometry, which converts deep earthquakes into virtual seismometers, to [...]
Non-stationary teleconnection between the Pacific Ocean and Arctic sea ice
Published: 2019-10-08
Subjects: Atmospheric Sciences, Climate, Oceanography and Atmospheric Sciences and Meteorology, Other Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Over the last 40 years observations show a teleconnection between summertime Pacific Ocean sea-surface temperatures and September Arctic sea-ice extent. However, the short satellite observation record has made it difficult to further examine this relationship. Here, we use 30 fully-coupled general circulation models (GCMs) participating in Phase 5 of the Coupled Model Inter-comparison Project to [...]
Redox-informed models of global biogeochemical cycles
Published: 2019-10-07
Subjects: Biogeochemistry, Earth Sciences, Environmental Sciences, Physical Sciences and Mathematics
Microbial activity mediates the global flow of carbon, oxygen, nitrogen, and other elements, including climatically significant gases. However, non-photosynthetic microbial activity is typically not resolved dynamically or mechanistically in global models of the marine and terrestrial biospheres, inhibiting predictive capability. Understanding the global-scale impact of complex microbial [...]
Deep Low-Frequency Earthquakes Associated with the Eruptions of Shinmoe-dake in Kirishima Volcanoes
Published: 2019-10-06
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Volcanology
Deep low-frequency (DLF) earthquakes occur beneath the Kirishima volcanoes in southwest Japan at depths of 10–30 km. In this study, we aim to reveal the relationship between DLF earthquakes and volcanic activity including eruptions by relocating the hypocenters of the earthquakes using the network correlation coefficient method and detecting the earthquakes comprehensively using the matched [...]
Climate change resilient agricultural practices: A learning experience from indigenous communities over India
Published: 2019-10-06
Subjects: Agriculture, Biodiversity, Environmental Indicators and Impact Assessment, Environmental Monitoring, Environmental Sciences, Life Sciences, Physical Sciences and Mathematics, Sustainability
The impact of climate change on agricultural practices is rising question marks on future food security of billions of people in tropical and sub-tropical region. Recently introduced, Climate Smart Agriculture (CSA) techniques encourages the practices of sustainable agriculture, increasing adaptive capacity and resilience to shocks at multiple levels. However, in reality, it is extremely [...]
Controls of River Dynamics on Residence Time and Biogeochemical Reactions of Hydrological Exchange Flows in A Regulated River Reach
Published: 2019-10-06
Subjects: Biogeochemistry, Earth Sciences, Hydrology, Physical Sciences and Mathematics
Residence Time Distributions (RTDs) exerts an important control on biogeochemical translations in watershed systems. RTDs tend to follow time-invariant exponential, lognormal, or heavy-tailed RTDs that have power-law behaviors for long tails in headwater or low-order streams. However, there is increasing recognition that RTDs can be more complicated and time-variable in response to dynamic [...]
The water planetary boundary: interrogation and revision
Published: 2019-10-03
Subjects: Earth Sciences, Environmental Sciences, Hydrology, Physical Sciences and Mathematics
The planetary boundaries framework has proven useful for many global sustainability contexts, but is challenging to apply to freshwater, which is spatially heterogeneous, part of complex socio-ecological systems and often dominated by local dynamics. To date, the planetary boundary for water has been simplistically defined by as the global rate of blue water consumption, functioning as a proxy [...]