Modeling and Comparison of Data Obtained by GPR, for Geological / Structural Analysis of a Carbonated Ornamental Rock Quarry - Blocometry Validation - Case Study in Valinho De Fátima, Portugal

Portugal, in the continental and insular territory, has raw geological resources in diversity and quality that are materials for the manufacturing industries, particularly linked to the civil construction, architecture and public works with great weight in its exports, revealing to be one big producer of ornamental stones worldwide. In this industry, the presence of discontinuities, grain size, colour, textural anisotropy and porosity are factors that can determine the economic viability of the exploitations. For this, it is important to develop effective prospecting routines that allow the geological/structural fast analysis and economic potential assessment of the massifs and subsequent correct planning and dimensioning of the exploitations. This work intends to model and integrate data from the ground penetration radar (GPR), together with close-range photogrammetry, derived from an Unmanned aerial vehicle (UAV) imagery. The objective is to identify and determine the spatial distribution of the various elements by modelling the acquired data, as well as verifying the feasibility of the technical disassembly option adopted. We have used GPR as it is non-destructive, fast to deploy, survey, process and interpret. The acquired data were processed using the GPR-SLICE, where a 3D final dataset was obtained and interpreted. GPR and photogrammetric model was integrated and interpreted and validated with direct field observations. The model obtained showed in its upper part, an area corresponding to the presence of sludge from the cut of the rock, followed by a strip that corresponds to the oolitic limestone. Further down to the end of the block, the presence of oolitic limestone with crossed stratification is identifiable. There was a textural and structural correspondence between the GPR data and direct field observations. GPR did not reveal any major morphostructural discontinuity, validating the technical option of choosing the places where the cuts were made for their individualization, as the block was cut clean. The GPR and photogrammetry data integration method revealed to be complementary, where results were obtained easily, fast, and with centimeter accuracy. The same methodology presented, revealed to be cheap and effective for both localized studies and optimization of the overall quarry’s extraction plan and design.

Implications of the Fresnel-zone texture for seismic amplitude interpretation

The 3D reflection seismic response is associated with a zone (the Fresnel zone), rather than with a single point used in the idealized 1D convolution model. Unlike a point of incidence, the Fresnel zone is complicated by its textural characters that are defined by the dip and azimuth of microreflectors in the zone. The Fresnel-zone texture makes seismic amplitude interpretation more complicated than previously documented. A conceptual model suggests that seismic amplitude variations with offset (AVO), azimuth (AVAz), and frequency (spectral decomposition) were physically related to textural roughness, textural anisotropy, and textural scale of the Fresnel zone, respectively. Textural roughness is defined by the dip deviation of microreflectors and contributes to the AVO intercept and gradient. Textural anisotropy is defined by the degree of the preferred orientation of the microreflectors and directly affects the AVAz signature. Textural scale is defined by the spacing of the microreflectors and controls the selective frequency tuning in spectral decomposition data. The Fresnel-zone texture gives rise to amplitude variations that can not be accurately modeled by using a 1D reflectivity-wavelet convolution algorithm, and thus poses challenges to the reliability of many previous predictions of rock properties and thickness from amplitude. The AVO, AVAz, and spectral decomposition data should be used to characterize Fresnel-zone texture for predicting depositional facies, deformational fabrics, and hydraulic properties in the subsurface.

Combining Sol-Gel Chemistry and Extrusion Process Toward Generating First Vanadium Oxide Macroscopic Fibers

ABSTRACTUpon extrusion process, first vanadium oxide macroscopic fibers have been obtained. They are associated to longitudinal Young modulus from 15 to 25 GPa and depict strong high scale textural anisotropy as observed through cross-polarized microscopy. TEM observations and SAXS experiments reveal that those macroscopic fibers are made of nanoscopic ribbons associated to preferential orientation parallel to the macroscopic fiber main axis, while XRD and NMR investigations reveal a microstructure close to the V2O5.1.8H2O xerogels. These fibers can detect down to 0.1 ppm of ethanol within 16 seconds at 40°C.