C.R. Souza Filho

Development of symmetrical and asymmetrical fabrics in sheet-like igneous bodies: the role of magma flow and wall-rock displacements in theoretical and natural cases

Abstract Two orientations of fabrics are recognised in vertical dykes: a symmetric orientation associated with magma injected into non-deforming wall-rocks and an asymmetric orientation usually associated with external non-coaxial shearing, or magma injected into an active fault. The notion of two fabric arrangements stems from two planes of symmetry, the dyke symmetry plane (DSP) and the fabric symmetry plane (FSP). This paper uses conceptual models to simulate all possible orientations of magma flow indicators that might be produced within a vertical dyke emplaced under coeval internal and external stresses. The effect of magmatic buoyancy-related stresses are portrayed in terms of magma flow velocities (MFV) and the external non-coaxial tectonic-related stresses in terms of wall displacement velocities divided by two (WMV/2). The tectonic setting is that of a sinistral transcurrent fault. Using these assumptions, five cases are proposed: MFV⪢WDV/2, MFV>WDV/2, MFV=WDV/2, MFV

Unravelling remote sensing signatures of plants contaminated with gasoline and diesel: An approach using the red edge spectral feature

Pipeline systems used to transport petroleum products represent a potential source of soil pollution worldwide. The design of new techniques that may improve current monitoring of pipeline leakage is imperative. This paper assesses the remote detection of small leakages of liquid hydrocarbons indirectly, through the analysis of spectral features of contaminated plants. Leaf and canopy spectra of healthy plants were compared to spectra of plants contaminated with diesel and gasoline, at increasing rates of soil contamination. Contamination effects were observed both visually in the field and thorough changes in the spectral reflectance patterns of vegetation. Results indicate that the remote detection of small volumes of gasoline and diesel contaminations is feasible based on the red edge analysis of leaf and canopy spectra of plants. Brachiaria grass ranks as a favourable choice to be used as an indicator of HCs leakages along pipelines.