Search results for "Geophysics"
showing 10 items of 2645 documents
Fold interaction and wavelength selection in 3D models of multilayer detachment folding
2014
Abstract Many fold-and-thrust belts are dominated by folding and exhibit a fairly regular fold-spacing. Yet, in map-view, the aspect ratio of doubly-plunging anticlines varies considerably from very elongated, and sometimes slightly curved, cylindrical folds to nearly circular, dome-like structures. In addition, the fold spacing often varies significantly around an average value. So far, it remains unclear whether these features are consistent with a folding instability. Therefore, we here study the dynamics of multilayer detachment folding, process by which shortening can be accommodated in thin-skinned fold-and-thrust belts. We start by analysing the physics of this process by using both …
Analytical and Numerical Investigation of 3D Multilayer Detachment Folding
2013
Multilayer detachment folding, in which a sequence of sedimentary layers is compressed above a weaker salt layer, is a common mode of deformation in thin-skinned fold-and-thrust belts. Here, we investigate the dynamics of multilayer detachment folding with three different viscosities: lower detachment or salt layer, overlying weak layers and competent layers. A semi-analytical solution, based on thick plate analysis of multilayer systems, is used to create mechanical phase diagrams of folding dominant wavelength and growth rate as a function of material parameters. The validity of the phase diagrams is tested and confirmed beyond the nucleation stages of folding by performing several 2D and…
Improved moment scaling estimation for multifractal signals
2018
A fundamental problem in the analysis of multifractal processes is to estimate the scaling exponent K(q) of moments of different order q from data. Conventional estimators use the empirical moments μ^[subscript r][superscript q]=⟨ | ε[subscript r](τ)|[superscript q]⟩ of wavelet coefficients ε[subscript r](τ), where τ is location and r is resolution. For stationary measures one usually considers "wavelets of order 0" (averages), whereas for functions with multifractal increments one must use wavelets of order at least 1. One obtains K^(q) as the slope of log(μ^[subscript r][superscript q]) against log(r) over a range of r. Negative moments are sensitive to measurement noise and quantization.…
Constraining nonstandard neutrino-quark interactions with solar, reactor and accelerator data
2009
We present a reanalysis of nonstandard neutrino-down-quark interactions of electron and tau neutrinos using solar, reactor and accelerator data. In addition updating the analysis by including new solar data from SNO phase III and Borexino, as well as new KamLAND data and solar fluxes, a key role is played in our analysis by the combination of these results with the CHARM data. The latter allows us to better constrain the axial and axial-vector electron and tau-neutrino nonstandard interaction parameters characterizing the deviations from the Standard Model predictions.
Neutrino Mass Ordering from Oscillations and Beyond: 2018 Status and Future Prospects
2018
The ordering of the neutrino masses is a crucial input for a deep understanding of flavor physics, and its determination may provide the key to establish the relationship among the lepton masses and mixings and their analogous properties in the quark sector. The extraction of the neutrino mass ordering is a data-driven field expected to evolve very rapidly in the next decade. In this review, we both analyze the present status and describe the physics of subsequent prospects. Firstly, the different current available tools to measure the neutrino mass ordering are described. Namely, reactor, long-baseline (accelerator and atmospheric) neutrino beams, laboratory searches for beta and neutrinol…
Synthesis of refractory metal nuggets and constraints on the thermal histories of nugget-bearing Ca, Al-rich inclusions
2015
Tiny refractory metal nuggets are mainly observed inside Ca, Al-rich inclusions (CAIs) from chondritic meteorites and are commonly assumed to be condensates from a solar composition gas. However, recent detailed studies of metal nugget compositions and their comparison with predictions from condensation show that the observed abundance patterns are extremely difficult to achieve in this way. As a test for the proposed alternative, precipitation from a silicate liquid, we conducted melting experiments, in which nine different refractory metals (nugget components) were equilibrated with each other along with a CAI-like liquid at reducing conditions. When quenched, minerals similar to those in…
Tectono-biosedimentary recordings at the Lias-Dogger transition: example of the Quercy carbonate platform (Aquitaine Basin, France).
2007
AbstractOn the eastern edge of the Aquitaine Basin, the Lias-Dogger transition and the events, which occurred during this time interval are studied in the Quercy sedimentary basin. Stratigraphic correlations are proposed using a biochronological calibration based on the determination of numerous ammonites and brachiopods. Facies analyses using statistical processing integrate the presence of faults and tectonic compartments and lead to reconstruction of palaeoenvironments in space and time. The paper includes the description of system tracts following Haq et al. [1987] and Vail et al. [1991], and twelve palaeogeographic maps of the area studied. The objectives are to distinguish the various…
Mineralogical and chemical variability of fluvial sediments 2. Suspended-load silt (Ganga–Brahmaputra, Bangladesh)
2011
Sediments carried in suspension represent a fundamental part of fluvial transport. Nonetheless, largely because of technical problems, they have been hitherto widely neglected in provenance studies. In order to determine with maximum possible precision the mineralogy of suspended load collected in vertical profiles from water surface to channel bottom of Rivers Ganga and Brahmaputra, we combined Raman spectroscopy with traditional heavy-mineral and X-ray diffraction analyses, carried out separately on low-density and dense fractions of all significant size classes in each sample (multiple-window approach). Suspended load resulted to be a ternary mixture of dominant silt enriched in phyllosi…
Rapid shifting of a deep magmatic source at Fagradalsfjall volcano, Iceland
2022
AbstractRecent Icelandic rifting events have illuminated the roles of centralized crustal magma reservoirs and lateral magma transport1–4, important characteristics of mid-ocean ridge magmatism1,5. A consequence of such shallow crustal processing of magmas4,5 is the overprinting of signatures that trace the origin, evolution and transport of melts in the uppermost mantle and lowermost crust6,7. Here we present unique insights into processes occurring in this zone from integrated petrologic and geochemical studies of the 2021 Fagradalsfjall eruption on the Reykjanes Peninsula in Iceland. Geochemical analyses of basalts erupted during the first 50 days of the eruption, combined with associate…
Performance assessment of PPP surveys with open source software using the GNSS GPS-GLONASS-Galileo constellations
2020
In this work, the performance of the multi-GNSS (Global Navigation Satellite System) Precise Point Positioning (PPP) technique, in static mode, is analyzed. Specifically, GPS (Global Positioning System), GLONASS, and Galileo systems are considered, and quantifying the Galileo contribution is one of the main objectives. The open source software RTKLib is adopted to process the data, with precise satellite orbits and clocks from CNES (Centre National d&rsquo